lighting & power design citam

Edson Engineers

EDSON ENGINEERS.

DESIGN CALCULATIONS.

LIGHTING AND POWER DESIGN CALCULATIONS.

BY

FRED BUTETE WAMBASI.

PROJECT: CITAM KAREN BOYS AND GIRLS TOILETS

JANUARY 2015

Power

DesignCalculations

Lighting

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1.0 Lighting Design.

1.1 Formulae and Fundamental Considerations.

Lighting design aims at determining the number of lighting fixtures (luminaries)

required in order to achieve the recommended illumination for a given task.

Key considerations prior to design are;

The dimensions of the room; Length, Width and mounting height of the

luminaire from working plane.

The nature of ceiling, walls, and floors in terms of coluor and material.

The functionally/use of the design area to be illuminated.

Non analytical factors affecting the choice of luminaires, aesthetics and

natural lighting.

In determining the number of lighting fixtures (luminaries) required, key among

other factors; the following has to be established:

Recommended illuminance (Lux) in Lumens/m²

Utilization factor

Maintenance factor of the Luminaire

Nominal lamp Luminous flux/output in Lumens.

Quantity of light here is specified by illuminance which is measured in lux (lm/m2

of illuminated surface).

The Lumen method formula used is as below (as per CIBSE Lighting guide and a

textbook on building services engineering by David V. Chadderton: Building Services Engineering

Fifth edition (2007) - Taylor and Francis Group - New York ).

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= Øn xn xMf xUfWhere:

E = Average recommended illuminance (Lux) in Lumens/m²

A = Area of the working plane (m²)

Øn= Nominal Lamp Luminous Flux

Mf = Maintenance factor

Uf = Utilization factor

N= Number of Luminaires

n= No. of luminaire’s lamps

1.2 Definitions:a. Utilization factor (Uf)

This represents the proportion of luminous flux of the lamp that reaches the

working plane and is dependent on the following:

Luminaire efficiency

Lighting fitting distribution

Reflectances of the room surfaces i.e. ( Ceiling, walls and floor)

Room index.

The room index represents the geometrical ratio of the area of the

horizontal surfaces to that of the Vertical surfaces measured from the

working plane in the room and is expressed as:

Ri = (L x W)( + )Where:

L = Length of the room

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W = Width of the room

Hm = Height of the Luminaire above the working plane.

The room reflectances depend on the room surface finishes. In my design

the ceiling is painted white, floor is terrazzo/pvc tiles in some areas and the

walls are painted white.The design reflectance ratio used is C: W: F = 0.7:

0.5: 0.2. Hm of 2.05m is used herein in design calculations.

Standard photometric tables for a combination of various values of room

indices and surface reflectances exist (given by manufacturers) from

which the value of the utilization factor (Uf) was directly obtained or

extrapolated for values of Room indices that were not integers as follows:= ( ) + ( − ( ) ( ) − ( )( ) − ( )where: (U= upper Value& L= Lower Value)

b. Maintenance factor (Mf)

This gives the proportion of illuminance provided by a luminaire in normal

working conditions (dirty conditions) of both the luminaire and the room

surfaces to the illuminance of the same luminaire in clean conditions.

For this design, I used a maintenance factor of 0.8 on the assumption that

the room surfaces will be maintained very clean most of the times given

this is children’s toilet where high standards of cleanliness are desired.

c. Nominal Lamp Luminous Flux (Øn)

The value was obtained from lamp photometric data usually provided by

manufacturers in the catalogues.

d. Illumination level (E)

These were read from a chart guide used for obtaining recommended

illuminance (Lux) prepared by the Chartered Institute of Building Services

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Engineers (CIBSE) and the Philips Lighting design Manual. These values

entirely depend on the type of use the room is put into. The illuminance are

as summarized in the tables below:

The following are the recommended Illumination Levels;

a) Hospital

Item Description Recommended

Lux (E) in

Lumens/M2

1.0 Corridors: Night

Daytime/ Evening

50

200

2.0 Wards: Circulation at night

Observation at night

General Lighting

Simple Examination/Reading

30

5

150

300

3.0 Examination Rooms: General Lighting

Local Examination

Lighting

500

1000

4.0 Intensive therapy: Bedhead

Observation

50

750

5.0 Nurses Stations 300

6.0 Operating Theaters: Pre-Op room

General theater lighting

-

500

1000

-

7.0 Laboratories & Pharmacies: General Lighting

Local

750

1000

8.0 Consulting Rooms: General Lighting

Local

500

750

9.0 Autopsy Rooms: General Lighting

Local

750

5000

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b) Offices


Lux E in Lumens/M2

1.0 General offices with typing, computers e.t.c 500

2.0 Conference rooms 300

3.0 Archives 200

c) General Building areas


Lux E in Lumens/M2

1.0 Circulation areas, corridors 100

2.0 Cloak rooms, toilets 100

3.0 Stores, Stock rooms 100

4.0 Stairs, escalators 150

d) Kitchen Block


Lux E in Lumens/M2

1.0 Servery 300

2.0 Kitchen 500

3.0 Food stores 150

4.0 Food preparation area 500

5.0 Cold store 300

6.0 Office 500

7.0 Kitchen yard 30

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e) Laundry Block


Lux E in Lumens/M2

1.0 Pressing 500

2.0 Sewing/Mending 750

3.0 Gents/Ladies 100

f) Workshop Block


Lux E in Lumens/M2

1.0 Welding 300

2.0 Machine work, coil winding 500

3.0 Fine bench & Machine work 750

4.0 Testing/ adjusting Electrical components 1000

2.0 Lighting Design Task.

2.1 Boys Toilets.

2.1.1 Area Outside toilets having whbs within toilet block.

The room dimensions are:

Length of the room, L = 8.9m

Width of the room, W = 5.8m

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For this toilets, the design illuminance E = 100 Lux as the lighting requirements are

for cloak rooms and toilets. The luminaire chosen was 1200mm 1x36W

ELECTRONIC BALLAST single batten fluorescent fitting with acrylic diffuser as

pierlite. For this fitting, the nominal luminous flux Øn = 5400 lumens per lamp.

Height of the luminaire above the working plane Hm = 2.05m

Therefore the room index Ri = L x W

Hm (L + W)

= 8.9 x 5.8 = 1.40

2.05(8.9+5.8)

From the photometric tables, and by extrapolation, the utilization factor is

obtained as

= ( ) + ( − ( ) ( ) − ( )( ) − ( )= 59 + (1.40 − 1.25) . .

=62.09% = 0.6209

The number of luminaires is given as,= 100 51.623450 x1 x0.8 x0.6209= 3.0122

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Thus we use 3 No.Luminaires,1200mm 1x36W Electronic Ballast single

batten fluorescent fitting with acrylic diffuser as pierlite to provide lighting for the

area.

This gives an illuminance of :

= Øn xn xMf xUfxNA= 3450 x1 x0.8 x0.6209x351.62= 99.59

Thislevel of illumination is acceptable as the luminaires will therefore provide

adequate lighting for the area required.

2.1.2 Area inside toilets having wcs but within toilet block.





for cloak rooms and toilets. The luminaire chosen was 16W Polo Opal C/W lamp

downlighter with

white lining. For this fitting, the nominal luminous flux Øn = 1250 lumens per lamp.


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Hm (L + W)

= 4.5 x 2.0 = 0.555351682

2.05(4.5+2.0)


obtained as

= ( ) + ( − ( ) ( ) − ( )( ) − ( )= 48 + (0.56 − 0.75) . .

=44.10% = 0.441


Thus we use 2 No.Luminaires, as 16W Polo Opal C/W lamp downlighter with

White lining to provide lighting for the area.

. This gives an illuminance of:

= Øn xn xMf xUfxNA

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= 1250 x1 x0.8 x0.441x29.08= 97.14



2.1.3 Paraplegic toilets.






downlighter with




Hm (L + W)

= 2.38 x 1.5 = 0.448830

2.05(2.38+1.5)


obtained as

= ( ) + ( − ( ) ( ) − ( )( ) − ( )

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= 48 + (0.449 − 0.75) . .=41.98% = 0.42






This level of illumination is acceptable (within + 30%) as the luminaires will

therefore provide adequate lighting for the area required.

2.1.4 Showers.




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downlighter with




Hm (L + W)

= 2.0 x 1.5 = 0.418

2.05(2.0+1.5)


obtained as

= ( ) + ( − ( ) ( ) − ( )( ) − ( )= 48 + (0.418 − 0.75) . .

=41.36% = 0.41


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This gives an illuminance of:

= Øn xn xMf xUfxNA= 1250 x1 x0.8 x0.41x13.57= 114.85This level of illumination is acceptable (within + 30%) as the luminaires will

therefore provide adequate lighting for the area required.

2.1.5 Area in front of cleaners’ room (corridor space).




For this toilets, the design illuminance E = 150 Lux as the lighting requirements for

this space. The luminaire chosen was 16W Polo Opal C/W lamp downlighter

with white lining. For this fitting, the nominal luminous flux Øn = 1250 lumens per

lamp.



Hm (L + W)

= 2.23 x 2.17 = 0.536

2.05(2.23+2.17)

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obtained as

Uf = 48 + (0.536 − 0.75) . .=43.72% = 0.44






This level of illumination is acceptable as the luminaires will therefore provide

adequate lighting for the area required.Being a room that is not used all day

illumination levels are however not as significant as in other areas of the block.

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2.2 Girls Toilets.

2.2.1 Area Outside toilets having whbs within toilet block.



Width of the room, W = 4.02


for cloak rooms and toilets. The luminaire chosen was 1200mm 1x36W

ELECTRONIC BALLAST single

batten fluorescent fitting with acrylic diffuser as pierlite. For this fitting, the

nominal luminous flux Øn = 5400 lumens per lamp.



Hm (L + W)

= 11.9 x 4.02 = 1.47

2.05(11.9+4.02)


obtained as

= ( ) + ( − ( ) ( ) − ( )( ) − ( )

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= 59 + (1.47 − 1.25) . .=63.4% = 0.634


Thus we use 3 No.Luminaires, 1200mm 1x36W Electronic Ballast single

batten fluorescent fitting with acrylic diffuser as pierlite. to provide lighting for

the area.

This gives an illuminance of :




2.2.2 Area inside toilets having wcs but within toilet block.




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downlighter with




Hm (L + W)

= 10.215 x 2.0 = 0.816

2.05(10.215+2.0)


obtained as

= ( ) + ( − ( ) ( ) − ( )( ) − ( )= 48 + (0.816 − 0.75) . .

=49.32% = 0.4932




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2.2.3 Paraplegic toilets.






downlighter with white lining. For this fitting, the nominal luminous flux Øn = 1250

lumens per lamp.



Hm (L + W)

= 2.0 x 1.5 = 0.585

2.05(2.0+1.5)

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obtained as = ( ) + ( − ( ) ( ) − ( )( ) − ( )= 48 + (0.585 − 0.75) . .

=44.7%=0.447

The number of luminaires is given as,= 100 3.01250 x1 x0.8 x0.447= 0.67Thus we use 1 No.Luminaires, as 16W Polo Opal C/W lamp downlighter with



= Øn xn xMf xUfxNA= 1250 x1 x0.8 x0.447x13.0= 149



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3.0 Power Design.

3.1 Formulae and Fundamental Considerations.

The following formulae as provided in the IEE Wiring regulations 17th Edition (BS

7671:2008) and its guide: Design and Verification of Electrical Installations by

Brian Scaddan( IEng, MIET) – Newnes Publishers UK (2008) were used in

calculations pertaining to power.

3.1.1 Design current I b

This is defined as ‘the magnitude of the current to be carried by a circuit in

normal service ’ , and is either determined directly from manufacturers’ details

or calculated using the following formulae as provided by 17th Edition of IEE

wiring regulations :

3.1.1 (a) Single phase loads. = or =3.1.1 (b) Three phase load= √ or = √ %

In both cases where:

P _ power in watts

V _ line to neutral voltage in volts

V L _ line to line voltage in volts

Eff% _ efficiency

PF _ power factor.

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3.1.2 Diversity

The application of diversity to an installation permits, by assuming that not all loads

will be energized at the same time, thus a reduction in main or distribution circuit

cable sizes. The IEE Regulations Guidance Notes or On-Site Guide tabulate diversity in

the form of percentages of full load for various circuits in a range of installations.

However, it is for the designer to make a careful judgement as to the exact level of

diversity to be applied by consideration of the actual design intended, most a times

designer judgement is employeds .

3.1.3 Nominal rating or setting of protection In.

In is that it should be greater than or equal to I b. We can select for this condition

from IEE Regulations Tables 41.2, 41.3 or 41.4. For types and sizes outside the scope of

these tables, details from the manufacturer will need to be sought.

3.1.4 Selection of suitable conductor size .

Based on the quantity of current anticipated. This is obtainable from calculations and

reference to standard cable rating tables.

3.1.5 Sizing the protective device

According to IEE regulations:Ib≤ II ≤ IcWhere:Ib= Design current of the circuitII = Nominal current or current setting of the protective deviceIc = Current carrying capacity of the conductor in the particular installation

conditions

3.1.6 Voltage drop

In many instances this may well be the most onerous condition to affect cable sizes.

The Regulations require that the voltage at the terminals of fixed equipment should

be greater than the lower limit permitted by the British Standard for that equipment,

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or in the absence of a British Standard, that the safe functioning of the equipment

should not be impaired. These requirements are fulfilled if the voltage drop between

the origin of the installation and any load point does not exceed the following values

(IEE Regulations, Appendix 12) ( Table 3.1 Below ). Standard cable current ratings are

tabulated against voltage drop in milli-volts (mV) dropped for every ampere of

design current (A), for every metre of conductor length(m), case of Tables 9D1, 9D2,

9D3, 9E1 etc in BS Code i.e.

Volt drop = mV/A/m (IEE 17th Edition)

Table 3.1

Lighting Power

3% 5%

240V Single phase 7.2V 12V

415V three phase 12.5V 20.8V

or fully translated with Ib for A and L (length in metres) as below formulae:

Formulae.

= volts = Vd = I x ∂ x L Volts (IEE 17th Edition)

3.2 Power Calculations for Both toilet Blocks.

3.2.1 Fixed power loads on distribution boards calculations, power supply cable and

protective switch gear sizing.

The ratings of the cable size and protective switch gear at the distribution board for

individual equipment /appliance is established from its load current during starting

operation voltage drops are pertinent in proper cable sizing and safety of operation.

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3.2.1( a ) Calculations.

The loads are single phase and thus single phase distribution supply adopted for

economic justification.

Formulae for calculation is provided above (also indicated below) as per IEE Wiring

standards . = ( )or = ( )

3.2.1(b) Hand drier spur point Cable Sizing and Circuit breaker rating.

Consideration during design is made for each spur point.This is performed assuming

the hand drier is in full operation. Ideal Load due to hand drier is used, Assuming

diversity of 1. = = 3000240 0.8 = 15.63From IEE Wiring Regulations tables, a cable of 2.5mm2 SC PVC insulated copper

cables is sufficient for the operation, however considering the overshoot during start

operation 4.0 mm2 SC Insulated by PVC copper cables can be used to cater for the

in currents rush as the case of a childrens’ toilet and also considering that the

distance from the DB to the spur point is very short, thus negligible economic

implications. (BS 6004 , BS 6346)

Thus a 20 A Double pole switch is chosen for the hand drier.

A protective circuit breaker of 20 A TP MCB is chosen for hand drier circuit.

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3.2.2 Current to CU’s, Cable Sizing for Armoured Cable and Choice of MCCB.

3.2.2(a) CU – CA , Girls toilets.

Total load on CU – CA in Kw is given in the table below.

ITEM NO RATING Total

Wattage(KW)

TotalWattage x1.8TotalWattageforFluorescent(Watts)Fittings

Diversity Applying aDiversity

(KW)

Flourescent

Lights

3 0.036 0.108 0.194 0.9 0.175

Security

Lights

4 0.060 0.240 - 0.5 0.120

Down

Lights

5 0.016 0.080 - 0.9 0.072

Double

Poles

1 3.0 3.000 - 0.7 2.100

TOTAL KW 2.467

ASSUMING PF = 0.8 KVA 1.974

Table3.2

Total load supplied to CU – CA was 2.467 Kw.

Allowing for 10% Extra Load for future additional load.

2.467Kw + 10/100*2.467Kw = 2.714 Kw

Design Load Current = . = 14.14 A

The maximum allowed voltage drop is 5% of 240 V0lts = 12V= volts = Vd = I x ∂ x L Volts

Since the CU’s are approximately 45 m from Maintenance workshop,

Maximum value of ∂ = Vd /( Ib x L) Volts = 12 / (14.14 x 45) = 18.86 Mv/A/m ,thus a

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Armorued cable of 4mm2 with a voltage drop of 12 Mv/A/m is chosen. Giving a total

voltage drop of:

Vd = 14.14 x 12 x 45 x 10-3 Volts = 7.64 Volts.The MCCB chosen is 20 A.

Since ; Ib≤ II ≤ IcWhere:Ib= Design current of the circuitII = Nominal current or current setting of the protective deviceIc = Current carrying capacity of the conductor in the particular installation

conditions

Ib = 14.14 A, II = 20 A Ic = 37 A.

3.2.2(b) CU – CB , Boys toilets.

Total load on CU – CA in Kw is given in the table below.

ITEM NO RATING Total

Wattage(KW)

TotalWattage x1.8TotalWattageforFluorescent(Watts)Fittings

Diversity Applying aDiversity

(KW)

Flourescent

Lights

3 0.036 0.108 0.194 0.9 0.175

Security

Lights

5 0.060 0.300 - 0.5 0.150

Down

Lights

6 0.016 0.096 - 0.9 0.086

Double

Poles

1 3.0 3.000 - 0.7 2.100

TOTAL KW 2.511

ASSUMING PF = 0.8 KVA 2.009

Table3.3

Total load supplied to CU – Cb was 2.511 Kw.

Allowing for 30% Extra Load for future additional load.

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2.511Kw + 10/100*2.511Kw = 2.762 Kw

Design Load Current = . = 14.39 A

The maximum allowed voltage drop is 5% of 240 V0lts = 12V= volts = Vd = I x ∂ x L Volts

Since the CU’s are approximately 45 m from Maintenance workshop,

Maximum value of ∂ = Vd /( Ib x L) Volts = 12 / (14.39 x 45) = 18.53 Mv/A/m ,thus a

Armorued cable of 4mm2 with a voltage drop of 12 Mv/A/m is chosen. Giving a total

voltage drop of:

Vd = 14.39 x 12 x 45 x 10-3 Volts = 7.77 Volts.The MCCB chosen is 20 A.

Since ; Ib≤ II ≤ IcWhere:Ib= Design current of the circuitII = Nominal current or current setting of the protective deviceIc = Current carrying capacity of the conductor in the particular installation

conditions

Ib = 14.39 A, II = 20 A Ic = 37 A.

……………………………………………..end……………………………………………

lighting & power design citam

Engineering

lighting design

room reflectances

design area

room length

power design calculations

floor room index

room surface finishes

design reflectance ratio