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Electrical Work in Schools.Ontario Dept. of Education, Toronto. School Businessand Finance Branch.7321p.; Prepared by Architectural Services-PlanningOntario Government Book Store, 880 Bay Street,Toronto, Ontario MSS 1Z8 ($2.00, checks payable toTreasurer of Ontario. Payment must accompanyorder)

EDRS PRICE MF-$0.75 HC-$1.50 PLUS POSTAGEDESCRIPTOPS Climate Control; *Electrical Systems; *Electric

Circuits; *Electricity; Fire Protection; IlluminationLevels; Lighting; *Lighting Design; *SchoolPlanning

IDENTIFIERS Canada; Ontario

ABSTRACTMost buildings rely on electricity for lighting,

power, sigAials, and other communications. Electric energy is alsoused for heating and year-round thermal conditioning of spaces. Itsease of transmission, simple control and measurement, and relativesafety make it a useful source of energy. This publication isintended to provide those persons responsible for the provision andoperation of educational facilities with a general description of thepresent state of accepted electrical design for schools and to givesome indication of future trends. (Photographs may reproduce poorly.)(Author)

4"1" Ministry Minister of Education

of Hon. Thomas L. Wells

EducationOntario

Ele rical orkin Schools

U S DEPARTMENT OF HEALTH.EDUCATION& WELFARENATIONAL INSTITUTE OF

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Contents

Introduction

General Considerations

Electric Services

Distribution System 5

Lighting 6

Light Sources 7

Area Design Considerations 8

Thermal Environment 12Alarm and Communication Systems 14

Lightning Protection 19

Terminology 20

Prepared byArchitectural Services-Planningin conjunction withRybka, Smith & Gins ler,Electrical Engineers

School Business and Finance BranchMinistry of EducationOntario 1973

Introduction

Most buildings rely on electricity for lighting,power, signals, and other communications.Electric energy is also used for heating andyear-round thermal conditioning of spaces.Its ease of transmission, simple control andmeasurement, and relative safety make ita useful source of energy.

This publication is not intended to be a hand-book for the consulting electrical engineer.Its intent is to provide those persons respon-sible for the provision and operation ofeducational facilities with a general descriptionof the present state of accepted electricaldesign for schools and to give some indicationof future trends.

General Considerations

The UtilityOntario Hydro is responsible for the generationand transmission of electric power in theProvince of Ontario. The retail distribution ofthis power is generally the responsibility ofthe various municipal electrical utilities thatown and operate the distribution systemswithin their respective areas. These localutilities obtain their supply of power fromOntario Hydro at cost under contractarrangements.

Ontario Hydro owns and operates "RuralHydro" serving farmlands and cottage areasin addition to certain built-up unincorporatedarea% where distribution costs are high incomparison to revenue.

Th a respective duties and responsibilities ofOntario Hydro and the local municipalelectrical utilities are outlined in two acts ofthe Ontario legislatureThe Power Commis-sion Act and The Public Utilities Act.

The Codehe Electrical Safety Code and Ontario Hydro

supplements are the standards of requirementsfor electrical installations in Ontario buildings.Their purpose is to ensure safety. In thisregard, they establish essential requirementsand minimum standards and make provisionsfor the prevention of fire and the promotionof proper operation and maintenance.

InspectionThe basis of inspection is The Electrical SafetyCode and any supplementary regulationsissued periodically by the Inspection Depart-ment of Ontario Hydro. This departmentconsists of the head office, which is respon-sible for standards and policy, and localoffices throughout the province, which areresponsible for on-site inspections of all newor altered electrical installations.

RequirementsConstruction plena must be submitted to theInspection Department of Ontario Hydrofor approval. Each project is inspected, and theelectrical work is subject to approval as theactual construction progresses. A certificateof approval is issued upon completion.Permanent electrical power is not connecteduntil the Inspection Department has approvedthe installation.

The electrical contractor is normally requiredto arrange for the inspections, pay anynecessary fees, obtain the certificates ofapproval, and present them to the owner.

The building owner should ensure thatconformity to the Code is adhered to through-out the life of the building by insisting thatany electrical additions to a building or modi-fications to existing equipment are inspectedand approved by the Inspection Departmentof Ontario Hydro.

Electric Services

An electric service is that part of a building'selectric system that connects the utility'sdistribution system to the building's distribu-tion system It includes such items as connect-ing conductors, a disconnecting switchwith protective over-current devices, andmetering apparatus. It may also includetransformation facilities.

Local utility policies with respect to servicearrangements may offer the customer somechoice. If the building's electrical load is small,service may be obtained at secondary orutilization voltage. For larger loads, the utilitymay require the customer to take primaryor high-voltage service. In some cities ofOntario, a distribution system known asNetwork is available.

NetworkThis service arrangement consists of utility-owned transformer vaults located underthe sidewalks, from which secondary servicesof whatever voltage required are providedby the utility. These are interconnected toprovide reserves against overloading any partof the system.

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Secondary ServiceOne such arrangement is through overheadservice conductors. The utility usually provideswithout charge up to one hundred feet ofthese conductors within the property line.Many municipalities, however, now requirethat underground services be installed. Insome cases, the extra cost thus entailed, or aportion thereof, is paid by the building owners.

Primary ServiceThis arrangement involves high-voltageconductors, sometimes underground; a trans-former with a primary switch and overloadprotection inside or outside the building;larger secondary conductors from the low-voltage side of the transformer to the mainsecondary switch; and lightning protection.The building owner normally pays for all ofthis equipment.

Where the utility provides the transformer,it will invariably be oil-cooled. If located insidethe building, a transformer vault must beprovided. It must be constructed in accordancewith Code requirements to withstand possibletransformer explosion ard to confine anyresulting fire.

If the owner must provide the transformer,an outdoor, pad-mounted transformer, com-plete with primary protection and a vandal-proof steel enclosure or chain-link fence,will be the cheapest form of service arrange-ment available to him. Where indoor installa-tion is required, air-cooled transformers shouldbe considered. Although they are somewhatmore expensive than the oil-cooled variety, nospecial vault is necessary; thus there is anoverall saving.

For those institutions that require loads greaterthan, say, 300 or 400 kilowatts, larger equip-ment is necessary, and anything other thanoutdoor mounting is extremely expensive.

Transformers are noisy; they emit a hum of60 to 70 decibels. Their location and arrange-ment with respect to the school itself andthe buildings nearby should be carefullyconsidered.

Masonry walls around the transformer instal-lation and a location at a reasonable distancefrom all buildings will substantially reducethe noise problem.

Service ArrangementsThe following table indicates what may beexpected in the way of service arrangements.

Load Type

to 150 KW secondaryservice

any size net- secondarywork area service

150-400 KW primaryservice

over 400 KW primaryservice

Voltage

120/240, 120/208,or 600 volts

120/208 or240/416 volts4 KV to 8 KV

12 to 44 KV

MetersMeters form an integral part of the electricservice and are provided by the utility. They aresubject to government regulations regardingdesign and accuracy and are of two types:

Primary meters are costly to the utility and arenormally only used for very large loads.

Secondary meters are used for all secondaryservices and most primary-service installa-tions. They are located on the building side ofthe secondary-service switch. These metersoperate at lower voltage and thus areless expensive.

For all but the smallest rural schools, themeters will measure and record two quantities:the maximum demand, being the largestflow of electricity in kilowatts through themeter to the building over any thirty-two-minute interval during the billing period(usually one month); and the consumptionof electricity over the metered period inkilowatt hours.

RatesRecently, there has been a simplification ofrate structures throughout Ontario. Previously,a number of different rates applied to thesame buildingone for lighting, one for powei,and one for cooking. Now, a single rate usuallyexists to cover all usage in the building.This arrangement is beneficial to the buildingowner in that the building wiring system issimplified and requires less sub-division andonly one metering station.

Electricity is sold to all non - residential userson the basis of demand and energy consump-tion. The rates are designed to favour the userwho consumes energy at a more constantamount per hour throughout the billing period.Such a user will have a lower cost perkilowatt hour.

Conductors and Protective DevicesConductors, depending on their size, have adefinite maximum amount of current thatthey can carry without overheating andultimately melting. The proper current-carryingratings of the different sizes and types ofconductors and protective devices for use invarious situations are outlined in The ElectricalSafety Code.

An electric conductor of insufficient size forthe required load will tend to overheat andthereby constitute a definite fire hazard to thebuilding. Protective over-current devicesare employed to interrupt the flow of electricalenergy and cut it cff when the current ratingof the conductor is exceeded. These devicesalso protect against short circuits flowingthrough faults in the system.

A system is said to be properly co-ordinatedwhen the protective device immediately on thesupply side of a fault opens, isolating thefault. Further protective devices upstreamshould not open, so that only the faulty part isshut off and made dead. The protectivedevices in a system should be designed tooperate in this way.

Ground-Fault ProtectionIt is possible for an electrical system to beapparently correctly installed and still be in adangerous condition. An example of this isthe case of a school with metal relocatablepartitions. These partitions may becomeenergized by ground leakage, without properlydischarging the current to the ground. In thissituation, it is unlikely that normal over-currentdevices will provide any protection. For thisreason, consideration should be given tothe inclusion of ground-fault protectivedevices. This equipment is expensive, but it hasalready been made mandatory by Codeauthorities for installations such as swimmingpools.

Distribution System

Below: Main switchboardTop left: Emergency stop buttonBottom left: Lighting panelIn r 7

The distribution system is the means ofcon-veying electric energy throughoutthe buildingfrom the service entrance to the lightingfixtures, electric motors, electrically poweredequipment, appliance, and convenienceoutlets. A typical system consists of a switch-board fed by the electric service with outgoingbranch mains to lighting panels. shop panels,and electric motors.

SwitchboardThe main switchboard contains the mainservice switch controlling incoming power,the metering apparatus, and the branchswitches for each of the outgoing branchmains. Each of the switches, main and branch,incorporates a protective device with a ratingbased on the conductors it serves.

Lighting PanelsThe outgoing branch mains serving thelighting system terminate in lighting panels,with up to forty-two branches in each panel,from which branch wiring extends to thelighting fixture outlets.

Electric MotorsElectric motors have special requirements forprotection against overload or overheatingbecause they are characterized by a higherenergy requirement for starting than for theirnormal operating speed. For this reason, theyrequire a motor starter that will permit ahigher current flow for a short time (measuredin seconds) and subsequently a lower valueof protection as they continue to run.

Shop PanelsWhere laboratories and/or workshops are es-sential in the educational program of a school,such spaces usually have permanently installedequipment that requires more or less elaborateelectrical installations for power and control.

The panel serving the equipment should beseparate and under the control of the teacher.In learning areas used for sewing, typewriting,or accounting, the panel may be built intothe teacher's desk. Where the panel is too largefor desk mounting, as is likely in wood-working or metalworking shops, wall instal-lation adjacent to the teacher's stationis recommended.

Shop circuits must have a light indicatingwhen they are energized, as well as one ormore emergency stop buttons, usually locatedat the teacher's station and at the normal exits.

The branch-wiring circuits in the panel shouldbe clearly labelled to indicate the piece ofequipment being served.

Lighting

One of the major parts of the electrical contractwork, both in importance and in cost, willbe for lighting systems in the school. Lightingas a design element can enhance or defineparts of the building. The role of the illumi-nating engineer will be to provide designs togive light for the performance of visual taskswith a maximum of speed, accuracy, ease, andcomfort, and a minimum of eye strain andfatigue. In addition, lighting can be usedto define different spaces and even toevoke mood.

Design ConsiderationsThe design of any lighting installation involvesa consideration of many variables. Thequestions that must be asked to determinethe design approach are:

What is the purpose of the installation,i.e., is light for critical seeing tasks, for decora-tion, or for other reasons?

How severe is the seeing task and for whatlength of time is it to be performed?What economic considerations are involved?

The answers to these questions will determinethe amount of light that should be providedand the best means of providing it. The solu-tion will involve individual tastes and opinions,especially in matters of appearance; no onesolution to lighting will be the most desirableunder all circumstances.

In all teaching areas of the school, manydifferent tasks will be carried out. It is mostimportant that the lighting be carefullydesigned to provide the correct quantity andquality of light and to integrate it properlyinto the building's design.

Quantity of LightTo light a specific area, it is important that anappropriate number and size of fixtures beemployed and that the spacing between thefixtures be not too great. If the distancebetween fixtures is excessive, the distributionof illumination will be irregular with goodlighting provided directly below fixtures andinadequate lighting between them. Themounting height of the fixture will also be animportant factor in determining fixture spacing.In some locations, for certain types of tasks,it might be advantageous to concentrate lightover the work area. In other locations, non-uniform levels of illumination may be desired.

Special designs should be developed toobtain the proper effect.

The quantitative unit of measurement of lightis the footcandle. The following table indicatesthe illumination levels that may be expected inthe normal spaces encountered in a school; itprovides a guide to good present-day practice.

Levels of Illumination for Schools'Foot- Dekalux

Area candles # onon Tasks Tasks

Art rooms 70 75

Cafeteria 50 54corridors and stairways 20 22Drafting rooms 100 110General learning areas 70 75Gymnasiums 30-50 32-54Home economicsa) sewing 150 160b) cooking and ironing 50 54Laboratories 100 110Lecture roomsa) audience area 70 75b) demonstration area 150 160Library 70 75Lounges, rest-rooms, lockers,showers, and washrooms 20-30 22-32Offices 70 100 76-110Seminar rooms 70 75

Shops 100 110Study halls 70 75Typing rooms 70 75

'Adapted from the -Illumination Engineering Society Recommen-dations- in the IES Lighting Handbook. 5th Edition_

ClJality of LightAdequate quantity of light alone does notensure good illumination. Good quality is asimportant as quantity and usually more difficultto achieve. The factors involved in obtaininggood-quality lighting in any given spaceare many and complex, but glare, brightnessratio, diffusion, and colour are some of themost important.

Glare is any brightness that causes discomfort,interference with vision, or eye fatigue. Glareis difficult to measure but will be related to thebrightness of the source, the size of the source,the position of the source in respect to theusual lines of vision, the brightness contrast(brightness of the glare point as contrastedwith the adjacent surfaces), and the time overwhich the glare is encountered.

Another problem is the reflected glare fromshiny surfaces such as polished desk tops,machine metal, cellophane sheets, glossy

paper, etc. Wherever possible, care should betaken in locating the light sources withreference to the working plane to eliminatethis effect.

Excessive "brightness ratios" in the field ofvision are also undesirable. The ideal situationfor critical seeing is to have a backgroundbrightness equal to the brightness of thetask itself.

The colour of light has little effect on the visualefficiency. For the performance of ordinarytasks, no light source has an advantage overothers from the stanc:point of colour. However,in some specialized applications (notablycolour matching, colour discriminationprocesses, and the like) light source and colouroutput will be a factor in illumination quality.

Many recently constructed schools are air-conditioned. Since the heat generated by thelighting fixtures is an appreciable portionof the air-conditioning load, the light sourcewith the lowest heat generated per lumen ofoutput per unit of energy input should beconsidered. In most cases, fluorescent lightingwill be the most appropriate source to use,wherever possible.

Fluorescent fixture

Light Sources

The efficiency with which a light source fulfillsits purpose is expressed in terms of lumenstransmitted per watt of power consumed. Themain types of lamps that will be encounteredin school lighting are incandescent filament,fluorescent, mercury, and metallic vapour.Some indication otthe efficiency of theselamps can be given by comparing the lumenoutputs per watt of power consumed for each.

Type of lamp

incandescent

fluorescentmercurymetallic vapour

Lumens per watt

1F. to 23 approx.(depending on type)7260100

T )p: Incandescent lampE.ottom: Mercury vapour fixture

Operating CharacteristicsTo determine which is the most appropriatelamp for the job at hand, some knowledge isrequired of its operating characteristics. Thefollowing are some considerations:

the colour of the light source from the pointof view of the apparent colour of the lamp aswell as the colour rendition at the workingsurfaces below the lamp

the cost of the lamp per lumen of lightreceived

the physical dimensions of the lamp

maintenance considerations such aslamp life. Approximate lamp life of incan-descent lamps is 1000 to 2500 hours, fluores-cent lamps 7500 hours, and mercury lamps25,000 hours

the effect of ambient temperature on thelamp operation. For example, fluorescentlighting output is seriously reduced if theambient temperature drops below 30°F

incandescent lighting. It can be readilydimmed with standard dimming equipment;fluorescent lighting requires special dimmingballasts as well as dimmer equipment, which isexpensive. Dimming of mercury fixtures isimpractical

the operating considerations. Fluorescentlamp life, for example, is seriously reduced ifthe fixture is switched on and off frequently.Mercury lamps are very slow in ighting andthis may be a problem if immediate high levelsof light are required.

Area Design Considerations

The following are some comments and adviceregarding lighting layouts in the typical spacesthat will be encountered in schoolconstruction.

Learning AreaThis is a space of approximately 750 squarefeet, and the lighting should provide goodlevels of illumination.

Good illumination levels for difficult tasksvary. The following chart shows somerecommended levels.

Activity footr 9ndles

audio-visual 30 (fornote-taking)

drafting and bench work 100reading pencil material 70reading duplicated material(poorly produced) 100sewinr, 150

It will generally be found that to provide theabove levels of illumination, fluorescentfixtures are the most practical source. Thequestion then arises as to whether the fixturesshould be recessed into the ceiling, surface-mounted, or suspended. In many cases, thefire rating of the ceiling will dictate whetherrecessed fixtures can be used. If a recessedfixture is used, then an acceptable enclosureabove the fixture will be required to maintainthe fire rating of the ceiling.

Suspended fixtures should have an upwardas well as a downward component of light sothat ceiling surfaces adjacent to the fixturereceive good illumination. In this way, thecontrast between the bright source of thefixture and the adjacent surfaces is reduced.These fixtures should be carefully selected toensure that shielding is provided so that thelight source cannot be be seen directly fromthe normal viewing angles.

I t is most important that good illumination beprovided on chalkboard surfaces. This can beobtained by locating the standard ceilingfixtures in such a manner that there is a rowof fixtures close to the chalkboard, or byproviding a special ceiling or wail-mountedfixture directly over the chalkboard. The latterprovides the best chalkboard illumination.

The switching of the lighting fixtures in thelearning area should be carefully planned, withseparate switching provided for chalkboardlighting. The main ighting in the room should

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be switched in such a manner that whendarkened for audio-visual presentations,reasonable illumination can be maintainedover students' desks for note-taking.

Care should be taken in locating the fixturesto ensure that they are properly co-ordinatedwith movie screens, TV monitors, etc., andthat chalkboards or tackboards are notobstructed from view by suspended fixtures.

It is recommended that samples of the pro-posed fixtures should be reviewed and aninspection carried out to ensure convenientmaintenance accessto the fixtures before thespecification is finalized. If plastic componentsare used, then acrylic plastic should be speci-fied rather than styrene in order to minimizebreakage from brittleness and yellowingwith age.

The number of different types of fixtures usedthroughout the school, especially the fluores-cent fixtures, should be kept to a minimum.This will ensure the lowest per-unit cost duringtendering and will also simplify maintenanceprocedures.

Open Learning SpacesFixtures in this type of space provide thenecessary illumination levels on a modularbasis so that partitions, if required, can beerected without changes to the arrangementand number of fixtures in each space. Nor-mally, panel switching will be used for thesefixtures, and, if partitioning occurs, additionallocal switching can then be installed.

Corridors and LobbiesRecent experience in schools has shown thatfairly high levels of fluorescent lighting aredesirable in corridors to provide good levels ofillumination and a bright and cheerful effect.This can be effected by installing standardfixtures down the centre of the corridor or bycreating cove lighting along the perimeters.In lobby areas, the architect may suggestdecorative lighting because of the specie:architectural finishes in these locations. It isrecommended that corridor lighting beswitched from panels. There will be a lightingrequirement for staff access to the panel iflights are switched from the panel. It may bedesirable to leave a number of fixtures on in thecorridors throughout the night; theseshould be installed on separate circuits. Thesemay also be used as emergency lighting byproviding both a main and a secondary powersupply to them. An automatic transfer arrange-ment would then be required.

Gymnasium using mercury vapour fixtures

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Washroom, Locker, and Shower RoomsGood overall illumination is recommended inthese areas to encourage cleanliness. Fluores-cent lighting is highly recommended. Switch-ing of lighting in these locations should becontrolled from the lighting panel or by a keyswitch in the room to discourage tamperingwith the switches.

GymnasiumThe amount and type of lighting to be pro-vided in a gymnasium will depend onusage. For exhibitions and matches, 50 foot-candles are required. For general exercise andrecreation without spectators 30 footcandleswould suffice.

Those levels would apply for basketball, bad-minton, and similar sports.

Incandescent, fluorescent, or mercury lightingcan be used for gymnasium lighting. Thefixture chosen should have wire guards orrugged protection against damage by base-balls, basketballs, etc. As the mounting h3ightof the fixtures will be fairly high in most cases,the method of relamping of the fixtu,e shouldalso be considered. Fluorescent lIghting is oneof the more economical and prevalent methodsof providing gymnasium lighting. Recently,however, mercury lighting has been used withsome success. The brightness of the light

Industrial fixture

source should be carefully considered andkept to a minimum, especiwiy 'or sports suchas tennis or badminton.

Shops and LaboratoriesThese areas will often be spaces without sus-pended ceilings and will require an industrialtype of fixture. If there is any danger of thelamps being damaged by the work involved,protective wire screens should be installedover the fixture. If vibration is anticipated,which may present a problem with incandes-cent lamps, a special socket should be installedto ensure that the lamps do not vibrate loose.

Gymnatoriums and CafetoriumsThese areas present a problem in that they willprobably have a variety of uses, includingclassroom work or individual study workwhere ;earning area levels of lighting will berequired. For assembly or exhibition purposes,levels of 15 to 30 footcandles will be adequate.Dimming may be a requirement so that dif-ferent levels of light can be provided for usewith projectors or TV monitors, at which timelighting may have to be reduced to allowproper viewing while at the same timeproviding sufficient light for note-taking. Apreferable method of lighting such areas is to

provide incandescent lighting on dimmers, forassembly and exhibition purposes, supple-mented by fluorescent lighting on switches, forhigher le,"3Is of classroom lighting. A flexiblearrangement for the accent lighting would beto provide a track into which fixtures can beplugged as required to suit the job at hand.In a cafetorium or gymn3torium, stage lightingand power provision, along with a dimmersystem, should be considered. The degreeof sophistication will depend on the pro-posed usage. In any case, power should beprovided so that, if dimmer and stage-lighting provisions are not installed initially,portable systems could be rented and installedfor infrequent stage productions. The methodof relamping of the fixtures should be con-sidered, as ceilings in these spaces will berelatively high.

LibraryIn libraries high quality lighting and goodlevels of illumination are recommended withapproximately 70 footcandles at the work sur-face. A decision should be made as to whetherbook stacks will be permanent as this willradically affect the lighting arrangement. Ifmovable stacks or shelves are to be used,these should be terminated sufficiently belowthe ceiling so that a general lighting pattern inthe room will provide adequate lighting ofthe stacks.

Exit and Emergency LightingExit lights are required and should clearlydefine the exit routes. Thcre should be fixturesinstalled over all exterior doors to assist infire evacuation of the building.

Emergency lighting should also be providedalong all evacuation routes, stairwells, and inlarger areas such as open learning areas, thecafetorium, gymnasium, etc. Battery units willnormally be the most appropriate type oflighting to use here. These can be centralbatteries with several remote fixtures or,alternatively, if the fixtures are spread out overa large area, individual self-contained unitscan be employed. These should contain anautomatic charging facility as well as auto-matic transfer to the battery in the event of apower failure. The type of battery should beconsidered from a maintenance point of view.Nickel cadmium batteries, although moreexpensive initially, require considerably lessservice than the less expensive lead-acid typeof battery. Larger schools should consider astand-by motor generator set if the require-ment for emergency power is great, or if theschool includes such items as elevators.

Standby motor generator

fseasive

Outside LightingOutside lighting may consist of an illuminatedsign, roadway lighting, and, if there is in-sufficient spill-lighting from adjacent muni-cipal roadway fixtures, footpath lighting andparking lot lighting. Security lighting shouldalso be installed by using an inconspicuous fix-ture to provide general lighting of the perimeterof the building, especially dark niches. Park-ing lot lighting, if adjacent to the buildings,can most economically be provided by flood-lighting fixtures mounted on the wa Ils or roofof the building.

Care should be taken in the design of all out-side lighting, especially in residential districts,to ensure that bright sources are not an annoy-ance to the neighbours on adjacent properties.

TelevisionIf TV videotapes are to be prepared in theschool, then the audio-visual departmentshould be consulted to determine the extentof special lighting provisions for their prepara-ation. A wide range of provisions can beemployed, depending on the sophisticationof the work to be done.

Thermal Environment

Supplementary electric heating

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HeatingThere has been considerable interest in heatingby electricity in recent years. A number ofbuildings in Ontario have been so equipped,with varying degrees of success.

The advantages of electric heating include theefficient use of energy, cleanliness, ease oflocal control, absence of requirements forattendance and operation, lower capital cost,and flexibility and adaptability to expansionor change.

In addition, electric-supply utilities may offercertain concessions to customers usingelectric heating, and where electricity is thesole energy purchased for the building. Theseconcessions have included:

a reduced rating (as from commercial toindustrial);

a utility-supplied transformer plant;

provision of special controls to limit maxi-mum demands (by shutting off the energysupply to certain sections of the system attimes of high demandin such areas asdomestic hot-water heating and the heatingof storage and garagespaces).

The major disadvantage of electricity as aheating medium is its higher cost (per heatunit) as compared to that of natural gas or fueloil. This factor is significant in spite of thecomparative inefficiency of a fuel-fired heat-ing system. To ensure reasonable operatingcosts, it is recommended that heating energybe minimized by employing such designmeasures as increased building insulation,reduction of window areas, the use of double-glazed window units, and systems for therecovery of heat from the air before it escapesfrom the building.

These measures result in additional initial cost,and this cost must be set against savings inthe capital cost of the electric heating systemitself, if real values are to be made clear.

If electric heating is being considered for aschool, a cost-benefit analysis should becarried out on the basis of the comparativecost for the total owning and operating energy,i.e., the cost of a fuel and the electricityrequired for a fuel-fired system should becompared to the total cost for an electricalsingle-energy installation.

This analysis needs to be exhaustive andshould include such factors as:

the features of architectural design thataffect heating requirements;

the heating system itself, including costs;

the heat gains within the building fromlighting apparatus and occupants;

the expected schedule of operation and itseffect on heat requirements;

the reduction of the unit cost of electricity:longer hours of use and around-the-clockheating requirements lead to a lower real costof energy used for lighting and power.

Such analysis is an involved process, evenwith the assistance of the technical expertise

Roof-top heating/cooling unit

maintained by Ontario Hydro to advise onelectric heating. It is, however, a necessaryexercise, since, due to the high cost of theenergy, design shortcomings will make them-selves apparent by the amounts shown in thefirst heating season's electrical bills.

CoolingModern educational facilities, due to theirlarge volumetric spaces, high lighting levels(creating heat), extended hours of use, andcompact design, create a demand for mechan-ical cooling.

Where mechanical cooling (frequently, ifincorrectly, referred to as air conditioning) isto be incorporated into a school, a feasibilitystudy should be carried out to consider thetype of equipment to be utilized. Refrigerationmay be provided by a reciprocating com-pressor, a centrifugal compressor, or anabsorption refrigeration machine.

Included in the study should be considerationof the heat pump. Heat pumps optimize effi-cient energy use by removing heat frominternal areas that require cooling and utilizingit in perimeter areas that require heating.

There are two main types of heat pumps, thecentralized internal source pump and the de-centralized electric-hydronic loop system. Thecentralized system is usually associated withlarge buildings where the refrigeration unit isin a central location. The heat extracted fromareas requiring cooling is either stored in awater vessel for use at night and/or used toheat areas calling for heat rather than the heatbeing rejected to the atmosphere through acooling tower.

The decentralized system utilizes a number ofair-conditioning units (water-air heat pumps)connected to a closed loop water systemwhich absorbs the heat from the units on acooling cycle and rejects the heat from thewater to areas requiring heating. This systemis supplemented with an electric or fossil-fuel-fired boiler if the water loop temperature is notsufficient for the areas requiring heat.

Alarm and CommunicationSystems

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Fire Alarm SystemsThe Ontario Fire Marshal has jurisdiction overfire-protection measures in schools through-out the Province. Other classes of buildingssimilarly governed are hospitals, universitybuildings, government buildings, hotels, andtheatres. School buildings must also complywith local municipal fire-prevention rules.

The Fire Murshal's regulations are containedin the Ontario Building Fire Safety DesignStandard, 1971, a publication of the Ministryof the Solicitor General.

One of these regulations requires an "approvedelectrically supervised" fire-alarm system in allschools over 6,000 square feet in area or morethan two storeys in height. These alarm sys-tems are specially designed for fire-protectionpurposes and conform with the requirementsof the Canadian Standards Association (CSA)and the Underwriters Laboratories of Canada.Examples of the components have been testedby these authorities and bear the labels of oneor the other. The systems consist of:

stations, either "manual pull" type or auto-matic detectors, which sense either a rapidrise of temperature or fixed high temperatures;

alarms, which are electric bells, gongs, orhooters;

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a control panel containing relays and powersupply;

an annunciator, indicating the zone or areawhere the alarm originates;

a secondary power supply, normally requiredin schools that hove over 150,000 square feetof floor area.

The principle of electric supervision is that afault anywhere in the system will cause abuzzer to ring, allowing it to be promptlyidentified and dealt with. The fire alarm shouldalso be transmitted to the appropriate agencyfor action to be taken.

Plans must be submitted to the Fire Marshaland are approved when they meet his require-ments. Before the system is accepted, it shouldbe completely checked over by the systemmanufacturer and certified by him to be cor-rectly installed and in satisfactory operatingcondition. Often it is then tested while oper-ating by the local fire department. From timeto time, the system should be examined andreported on by a competent electrician familiarwith such systems.

Multiple security alarm panel

Security SystemsOther security systems are available, whichgive and transmit an alarm to an outside loca-tion such as a board office, the police, a firestation, or an independent protectioncompany. Examples of alarm functions oftenprovided are:

burglar alarms

low-temperature alarmsSince schools are closed and often unattendedduring regular and long weekends throughoutthe winter, they are vulnerable to failures oftheir heating systems with the attendantdamage caused by frost and water. Pr )mptnotification of the low-temperature conditionallows time for rectification.

a power-failure indication. It will give aneven earlier warning than the low-tempera-ture alarm, and may be included.

Telephone SystemThe practice is generally to restrict the use ofthe telephone system within the building tothose people who require the use of the tele-phone for school business. Pay telephonesmay be included for student and other staffusage and should be conveniently locatedthroughout the building.

The type of system and the number and loca-tion of outlets throughout the school, bothinitially and including projected growth, are

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Public Address and IntercommunicationSystemsAs a normal requirement, public address sys-tems are provided to allow voice messages,music, or other program material to bedispatched from a central equipment rackor console to individual or groups of learningareas throughout the building.

Main equipment is usually located in thegeneral office and includes the necessaryamplifying components and selective switch-ing to allow program material to be sent to anindividual learning area, groups of these, orall speakers throughout the school.

Microphone inputs are provided at the mainconsole as well as in designated offices, thestage, and other locations depending on theexpected use.

In each learning area, speakers are usuallyprovided of the "talk- back" type with anintegral microphone to allow two-way con-versation between these spaces and the main

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console. Room-to-room conversations are notpossible, but messages could be relayedthrough the person atthe main rack. A three-position switch is provided in each room toallow reception of messages only (privacysetting), signalling from the learning-area tothe main rack, and an off position. The switchshould be located out of normal student trafficpatterns to prevent misuse of the switches bythe students, especially between periods.Speakers are normally located above thechalkboards at the front of the learning areaor at the front of the side wall. Speakers in thecorridors are also provided, but without thetalk-back features.

In areas where high ambient noise levels areoften encountered, speaker horns are provided,with volume controls and a supplementaryhandset which, when operated, cuts offthe speaker and allows fora two-wayconversation.

In large spaces such as the cafeteria or gym-nasium, multi-speaker coverage is provided

to allow clear, even sound coverage through-out the space. In the gymnasium, speakersshould have wire-guard protection againstdamage. Speakers, if installed outside thebuilding, should be of a weatherproof type.

Clock or other program signals can be trans-mitted over the public address system byinterconnection of the program equipmentwith the P.A. system. A weatherproof speakercan also be provided at a receiving entranceto allow for remote identification of persons atthat entrance during day or night operation.

An intercom system can be used instead of, orto supplement, the public address system aspreviously described, by providing atelephone-type handset in each learning area,office, and maintenance centre.

The cheapest system is a simple one, allowingfor a conversation between any branch phoneand the central equipment at the main desk.

If the total number of telephones is not large,an "all-talk" system is available, with commontalking throughout all phones. With this sys-tem, conversation between learning areas ispossible. Signalling of the station to be con-tacted is the limiting factor in this system, sinceit involves separate push buttons and buzzer-signal wiring.

With larger systems, where privacy isrequired in conversations, or where room-to-room conversations and signalling are re-quired, a more sophisticated system can beemployed with central switching equipment.This is more expensive and will require spacefor the central equipment.

In gymnatoriums and cafetoriums, the normalspeakers included in the public address systemmay not be of a sufficiently high standard forthe programs that are often required in thistype of space. In these instances, direct soundfrom the front of the room is preferable, withspeakers located at the stage rather than dis-tribution through the speakers in the ceiling.Such systems usually involve separate ampli-fiers with input provisions for a tape, radio,movie projector, microphone, and TV sound.Alternatively, these systems can input to theschool's public address system.

Throughout the sound systems, good qualityequipment should be employed, and the wiringshould be of a high standard so that ease ofmaintenance is possible and alterations canbe easily carried out.

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Clock and Program SystemsAutomatic clock systems are normally pro-vided in new schools, especially in largerschools where correction of clocks could be amajor time-consumer for maintenance staff,in the event of power failure.

Clocks are usually provided in all enclosedlearning areas, as well as double-faced clocksin the corridors and open space areas. In theenclosed learning areas, it is preferable for theclock to be visible to all people; it is frequentlymounted on the side wall of the room abovethe entry door.

Clock systems usually employ a master clock,electrically operated with provision for theclock to continue running during a powerfailure. The master clock controls all clocksthroughout the building. Such systems areof the following types:

minute-impulse type with its own wiringsystem. The minute hand on these clocks

jumps one minute at the end of each minuteand no sweep second hand is available.

synchronous type with its own wiring sys-tem, but having a sweep second hand.

high frequency type with a high frequencysignal generator feeding into the regularelectric system in the building, and allowingsecondary clocks to be installed anywhere inthe building without requiring its own wiringsystem.

An economical type of installation uses anelectrically driven sychronous clock in eachlocation, but with a separate wiring systemallowing simultaneous correction from acentral point. This system does not require amaster clock.

A program system can be used in conjunctionwith the master-clock system and with pro-gram wiring installed in common conduitwith the clock wiring and, in some cases, usingcommon wiring. The program control unit isadjustable to allow programs to be changedfrom time to time. It should be establishedwhether the program will repeat on a twenty-four hour basis or on a one-week basis, as thiswill affect the choice of equipment.

The program system normally operates bellsin corridors, outside the building, and in areaswith high noise levels. In learning areas andother individual rooms, program buzzers arelocated in the clock or in the outlet box thatservices the clock. Sometimes visual signalsor tones are preferred to buzzers.

Normally, four separate programs are availableon any one program originator, although sixprograms can be obtained at additional cost.Some consideration should be given as towhether different programs are required indifferent areas of the building. If so, the wiringwill have to be installed so that programs canbe directed accordingly.

The program controller is normally mountednext to the master clock.

Sports timers in the gymnasium, with inputprovisions from the scorer's desk, are some-times provided. These are separate provisionsand are not connected to the clock system.

TelevisionWhere the use of television as a teaching aidis contemplated in a school, the extent of theinitial provisions will have to be carefully con-sidered. There should be sufficient flexibility

in the design of the building to allow futureinstallation of, or revision to, the TV cabledistribution. Accessible ceiling spaces wouldprovide such flexibility. However, where ceil-ings are inaccessible, an empty conduit isrecommended with outlets in each learningarea.

The types of programs that might be used ina learning area are "off-air" programs eitherfrom commercial channels or from the localETV (educational television) station or fromprograms that are originated in theschooland distributed "live" or by videotape. Atpresent, there is only one ETV channel in usein most locations, and the program scheduleused by the ETV stations in most cases is notalways convenient for class usage. As a result,VTR (videotape recordings) are made ofthese programs for distribution in the schoolat a more convenient time.

A central room may be provided for the audio-visual department from which TV programscan be distributed. This room will serve as thedistribution centre and will also serve as alocation for storing and repairing equipment,as a tape library, and as a place where tapescan be prepared. Central videotape recordingequipment can also be located at this pointfor the recording of live programs from otherpoints in the school.

If the area in which theschool is located isserved by cable TV, a connection to thatsystem is possible. If not, an antenna withhead-end equipment should be installed. Theinstallation should conform to the Departmentof Communication requirements for cable TVto allow for future connection to cable TVwithout expense at that time.

Colour TV might also be considered, as manymanufacturers of TV educational equipmentno longer make black and white units.

The distribution system can initially be forVHF (very high frequency) distribution, butshould be designed to allow ulitmate inclusionof UHF (ultrahigh frequency). Cable suitablefor UHF should be installed.

Two types of cable distribution systems areavailable: the RF (radio frequency) system orthe video system. In the RF system, all outletsare connected to one cable, with each learningarea able to select any of the channels in use.Programs are run on a schedule, and a learningarea has the option of using or not using theprogram being scheduled. It is noted that

"in- house" programs can be initiated onunused channels.

The video system has a radial distributionsystem, with each learning area connected onseparate conduit and wiring from the distri-bution centre. With this system, a learningarea requests a program and a program isdispatched from the distribution centre. Thecontrol of the program is from the distributioncentre. This is a much more expensive system,costing approximately ten times the cost ofthe RF system and is more commonly used inuniversities where a wider range of programselection is required and where better resolu-tion at the monitor set is necessary.

If temporary and portable equipment is to beused, the TV outlets should be mounted lowin the room with an adjacent power outlet.Ceiling-mounted sets are convenient and lesssubject to damage. Note that these sets shouldbe located with respect to high-glare sourcesso that reflections cannot be seen in the glassfront of the set. Outlets will be normallymounted adjacent to the window wall.

The outlets in the learning area can be one-way for reception of TV only or two-way,allowing reception as well as transmission ofa program to the distribution centre or to otherareas of the building. The two-way outlet is acompromise and may, however, jeopardizereception. As this outlet involves additionalexpense, it is definitely not recommenced fornormal learning areas unless it is known thatprograms may be originated in these rooms.

This would normally apply to the laboratory,gymnasium, and cafetorium. If there are notmany areas where programs will be originated,then it is recommended that separate lines forprogram origination outlets be provided atthese locations and that normal antennaprovisions also be included in these areas.

Some method of communication between thelearning areas and the TV distribution roomshould be considered, especially whereunscheduled programs may be available onunused channels for individual rooms. TheTV intercom equipment can be the plug-in,portable type and, with the addition of a smallamount of wiring, it can also include on-offswitching of the videotape at the TV centre toallow the teacher to co-ordinate the projectionof the videotape with other audio-visualequipment at the learning area.

Lightning Protection

Lightning is caused by the release of storedelectrical energy in a thundercloud to th eground. A thundercloud is, in fact, an electricalcell or combination of cells. It tends to benegatively charged at the base and positivelycharged at the top. Lightning is usually formedby a stepped leader process proceeding fromthe base of the cloud towards the ground. Asthe leader approaches the ground it induces ahigh positive potential in the earth below it,which results in a positive return streamerflowing upwards from the ground to thestepped leader. This action occurs at a muchfaster rate than the downstroke because of theformation of an ionized path by the steppedleader. The contact between the steppedleader tip and the upward return streamerresults in a discharge of enormous energy atthe ground, involving voltages counted in themillions. A return streamer may carry currentsas large as 200,000 amperes, although justover 10% of this is usual. These currents aremaximum in about 10 microseconds.

Few people realize that water, either in thematerial or on it, is turned into steam, in thisvery short period of time, by the heat generatedby the discharge. The rate of expansion of thegas created is explosive and this, in fact, is thecause of much of the damage associated withlightning.

Damage can be considerable and, for thisreason, some protective measures are neces-sary. Buildings in Ontario are required to haveprotection, more or less depending on theirexposure, in conformity with provincial legis-lation entitled the Lightning Rods Act. Theprinciple upon which the required protectionis based is that a lightning rod, a kind of metalspear mounted above the top of the buildingand connected to the ground by a low resist-ance conductor, provides an easy path forthe electric discharge from the sky and allowsit to pass harmlessly to the ground.

Regulations under the Lightning Rods Actprescribe point spacing for various types andarrangements of buildings, conductor sizes fordown leads, and required grounding arrange-ments. The grounding system is most impor-tant and is required to be kept separate fromgrounds required for other electric apparatusand systems. It normally consists of copperplates or wires buried at such depth as to bein moist earth at all times.

Certain contractors are licensed under theAct to install lightning-protection systems and,for this reason, lightning protection is oftenconsidered a separate trade from other elec-trical work. However, it may be proper toinclude it with other electrical work in the caseof more elaborate buildings where conduitwork for the system must be installed as thework progresses.

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Terminology

For those persons unfamiliar with the technicallanguage contained in the text, the followingexplanatory notes and definitions may beuseful.

Electric Services SectionConductors: wires, cables, or bars (called busbars), made of metals that have a low electric

a resistance to minimize transmission losses,e.g., copper or aluminum.

Protective over-current devices: fuses thatmelt and interrupt the flow of electric currentand circuit breakers that open by electro-magnetic or thermal action when the rating ofthe conductor is exceeded. With a few veryminor exceptions, a switch is also required.These switch and protective device combina-tions, singly or collectively, are calledswitchgear.

Faults and short circuits: a fault is an acci-dentally formed path for an electric flowbetween phase wires of a system or betweenone or more of the phase wires and the ground.The establishment of electric flow through thispath is called a short circuit.

Load: the amount of electric power that isbeing.used in an electric system at any instant.For a building or a substantial part thereof itwill be expressed in kilowatts (KW.).

Lighting SectionFootcandle: a footcandle is the measure ofillumination at a point on a surface that is onefoot from and perpendicular to a point lightsource of one candle. Footcandle readings areused to indicate the illumination of a specificpoint for the average illumination on a surface.

Dekalux: this is an SI unit equal to 1.076 foot-candles. One dekalux equals ten lux.

Brightness: the brightness of a light source ismeasured in candles per square inch fora verybright source and in footcandles for a reflect-ing surface. Several meters are available for themeasurement of brightness; however, theseare not as often used or are not as readilyavailable as the footcandle meter.

Lumen :the total output of a light source fallingon a surface one square foot in area, everypart of which is one foot from a point sourcehaving a luminous intensity of one candle inall directions.