Solid State Lighting

Inteltech brings the total solution to replace incandescent and CFL lamps

in most installations

Problems with CIE’s CRI

CQS Color Quality Scale“ Color rendering: Effect of an illuminant on the color appearance of

objects by conscious or subconscious comparison with their color appearance under a reference illuminant „ —CIE 17.4, )

International Lighting Vocabulary, (Schanda 2002)

CQS is being developed by NIST (National Institute of Science) to replace the outdated CRI measurements

The human eye works optimally when objects are illuminated with noonday sunlight (6500K). The white light from the sun includes all the light spectra from Blue to Red in equal proportions. We see the spectra an object reflects and does not absorb. If a light source does not have the full spectrum of the sun then objects do not appear their natural color.

CQS will replace CRI. Some of the CRI procedures will be retained but the test will test for a light to saturate the colors at the end of the spectrums. Light that score well on the CRI test will suffer under the CQS test.

SSL technology using High Brightness white LEDs score very high on CQS and low on CRI. LEDs can be made to score well under the CRI test but must sacrifice at least 20% of the efficiency to do so, and then would no longer render color as well.

Is it reasonable to use CRI as a measure of a SSL? Inteltech will provide whatever the customer wishes, but if efficiency and good color rendering is desirable then CQS is the preferred standard.

• Outdated and inaccurate for modern light sources •Only applies to lights below 5000K• Does not measure a light source’s ability to render color faithfully.• Does not work with modern LED technology because it penalizes lights that can fully saturate colors especially those that contain blue and green.• A score of 100 can be achieved with light sources which can illuminate the 8 low saturated colors used in the test, but fail to render bright colors accurately.• For instance, an incandescent lamp will score 100, but the light makes an object appear dull.• Manufacturers like GE and Sylvania in an attempt to offer full color rendering to their incandescent lamps are adding rare-earth phosphors to add blue and green/yellow spectra.

Benefits of SSL Lighting

Lamp/Bulbs vs LuminairesWhat do you get when you add four oranges to four apples? If you

multiply four cows times four cows, do you get 16 squares cows? Math can be tricky, so can lighting system comparisons.

A designer must be careful when comparing different lighting technologies for a project. A common error is to compare a lamp/bulb to a luminaire. A luminaire, by definition, is the combination of a ballast, enclosure, light source, and lens. A luminaire has both an optical efficiency and a power efficiency. Both efficiencies must be considered when selecting a luminaire. A lamp/bulb is placed in an enclosure and usually filtered with a lens. It is correct to compare one luminaire lumen output to another luminaire lumen output.

For example, a 200 watt incandescent lamp may put out 3200 total lumens, but when placed in a can light fixture 50% of the lumens are lost to internal reflection and focusing. So the usable light output is only 1600 lumens.

A SSL fixture is a complete unit: ballast, enclosure, and lens are integral to the design. The lumen level specified is the lumen level you will get.

A CFL (Compact Fluorescent) may put out 70 Lm/watt bare bulb, but when placed in a can light only 35 Lm/watt is usable. The fixture also builds up heat and shortens the bulb life appreciably.

A bare 4’ T8 or T5 lamp may put out 100 Lm/watt as specified on a data sheet. But the lamp is part of a lighting fixture which includes the ballast, the enclosure, and the front cover. Now the lumen output is reduced over 60% in some fixtures. What happens when the high voltages attract dust which coats the lens and lamps? The efficiency suffers even more.

When designing a lighting system make sure the comparisons are done luminaire to luminaire to get an accurate analysis.

• High Efficacy Luminaires• 46 Lumens/watt (5000K)• 38 Lumens/watt (4000K)

•100,000 hour life (DC version)• Uniform light output•Uniform color output• Full dimming with 0-10V Control• Low voltage DC operation• High Voltage AC operation (coming)• Four light color temperatures

• 5000K (most efficient)• 4000K• 3400K• 2900K (least efficient)

• Compact, flush mount design• Rugged, impact resistant, immune to moisture• Uses inexpensive plastic ceiling box for installation (no cans)• UL Approved for Class 1 and Class 2 wiring methods

Luminaire Life Expectancy

• Incandescents are being banned!The incandescent lamp is being banned from retail sales beginning in

2012 in the USA and Canada. Toshiba of Japan is stopping production in 2010. Certain higher efficiency units will be sold for a while but eventually the goal is to eliminate this technology from the face of the earth. Installing incandescents in a new building will result in substantial replacement cost within just a few years.

Incandescent lamps have changed very little from Edison’s first creation. Edison founded GE after he invented the light bulb. GE is now selling it’s lighting division because the lighting technology is ancient. There are an estimated 4 billion Edison sockets in the USA alone, it is staggering worldwide. Some improvements have occurred over the hundred years since then: for instance, the lamps use an inert gas to keep the filament from burning up instead a vacuum, also halogen has been added to help filament particles recombine on the filament to extend the life. Rare-earth phosphors are added to brighten the light so it will render color more accurately (see CRI discussion).

The first lamps were 2% efficient in creating light, 98% was heat. They are now approaching 20% efficiencies. Average Lm/watt for all incandescent lamps is about 10 Lm/watt according to the DOE. Some can reach 22 Lm/watt but have limited 1000 -2000 hour lifetimes.

The very nature of the filament structure makes them vulnerable to shock. The pressurized versions are dangerous. They run extremely hot and create heat loads on the air conditioning systems, and when improperly vented literally kill themselves.

The incandescent also suffers from rapid lumen loss. This complicates a lighting system design. The designer must over-design the lumen output because the actual performance will be 20% less over the life of the bulb.

Since non-SSL lamps/bulbs are part of a luminaire, how do we measure the life you get from the system of parts? Add in the fact that most of the fixtures are made in China these days, the quality is very poor. The ballast can fail, the socket wears out, the connections corrode. How many fluorescent fixtures are replaced due to broken connectors? How often will you replace a ballast? How often will the front lens need replacement due to discoloration and yellowing?

Silescent lights are milled from 6061 recycled aluminum and can be recycled over and over again. Silescent lights are designed and made in America, by Americans. The milled aluminum is hard anodized to make it impervious to corrosion. The fixtures are then powder coated to create a durable, lasting finish of any color. They can literally vanish into the ceiling. The lifetime specification is the entire fixture not just the lamp.

Is the CFL the final solution?

The mercury question?• How may people and businesses really bother following the suggestions

offered by the D.O.E.? Most end up I the trash. Count the number of ither items that must used to clean up the mean and be disposed of along with the CFL. The DOE is desperate or they would not recommend this lamp.

1. Before Clean-up: Air Out the Room• Have people and pets leave the room, and don't let anyone walk through the breakage area on

their way out. Open a window and leave the room for 15 minutes or more. Shut off the central forced-air heating/air conditioning system, if you have one.

2. Clean-Up Steps for Hard Surfaces• Carefully scoop up glass fragments and powder using stiff paper or cardboard and place them in

a glass jar with a metal lid (such as a canning jar) or in a sealed plastic bag. Use sticky tape, such as duct tape, to pick up any remaining small glass pieces and powder. Wipe the area clean with damp paper towels or disposable wet wipes. Place towels in the glass jar or plastic bag. Do not use a vacuum or broom to clean up the broken bulb on hard surfaces.

3. Clean-up Steps for Carpeting or Rug:• Carefully pick up glass fragments and place them in a glass jar with metal lid (such as a canning

jar) or in a sealed plastic bag. Use sticky tape, such as duct tape, to pick up any remaining small glass fragments and powder. If vacuuming is needed after all visible materials are removed, vacuum the area where the bulb was broken. Remove the vacuum bag (or empty and wipe the canister), and put the bag or vacuum debris in a sealed plastic bag.

4. Clean-up Steps for Clothing, Bedding, etc.:• If clothing or bedding materials come in direct contact with broken glass or mercury-containing

powder from inside the bulb that may stick to the fabric, the clothing or bedding should be thrown away. Do not wash such clothing or bedding because mercury fragments in the clothing may contaminate the machine and/or pollute sewage.

• You can, however, wash clothing or other materials that have been exposed to the mercury vapor from a broken CFL, such as the clothing you are wearing when you cleaned up the broken CFL, as long as that clothing has not come into direct contact with the materials from the broken bulb. If shoes come into direct contact with broken glass or mercury-containing powder from the bulb, wipe them off with damp paper towels or disposable wet wipes. Place the towels or wipes in a glass jar or plastic bag for disposal.

5. Disposal of Clean-up Materials• Immediately place all clean-up materials outdoors in a trash container or protected area for the

next normal trash pickup.• Wash your hands after disposing of the jars or plastic bags containing clean-up materials.• Check with your local or state government about disposal requirements in your specific area.

Some states do not allow such trash disposal. Instead, they require that broken and unbroken mercury-containing bulbs be taken to a local recycling center.

6. Future Cleaning of Carpeting or Rug: Air Out the Room During and After Vacuuming• The next several times you vacuum, shut off the central forced-air heating/air conditioning

system and open a window before vacuuming.• Keep the central heating/air conditioning system shut off and the window open for at least 15

minutes after vacuuming is completed.

• The CFL or Compact Fluorescent Lamp is a fluorescent tube bent around itself with the ballast in the base. It suffers all the same problems of the larger tube lamps.• Life expectancy is about 10,000 hours with the best units. However, since these lamps have starter filaments, the act of turning them on and off will shorten their life. Life is also affected by heat, many fail in a short time.• CFLs are fragile. Since the Edison socket does not give positive feedback, you do not know how hard to twist the bulb. A little too much pressure, and the thin glass envelope cracks, destroying the lamp. Screwing it in with just gripping the base isn’t practical with small can light fixtures.• CFLs require time to warm up to full brightness. They either do not dim at all or dim very little with visible flicker and audible noise.•Other lamps that contain mercury are:

•Mercury Vapor• All fluorescents• High Pressure Sodium (HPS)• HID’s

SSL advantages to TCO

• Total Cost of OwnershipInstalling a lighting system is a commitment to keep it operating at peak performance.

Everyone has experienced entering a store or hotel where the overhead or cove lighting is banks of fluorescent lights. The lamps are invariably mismatched in color from warm to cool white, sometimes in the same fixture. I doubt the lighting designer had those particular mixtures in mind. Manufacturers do not guarantee their light will match light color or light output to another competitors lamp. And yet, facilities managers buy from whatever source is available at the lowest cost.

Many of the lamps invariably flicker due a failing ballast, lamp wear, or a poor connection. They usually hum at the line frequency. Looking up at the hundreds of bulbs you can see the bare lamps covered in dust and those that have lenses are discolored or dirty. The dust is charged by the high voltages and is attracted to the lamps and fixtures. It is impossible to keep them clean. Dirt affects light output and therefore system efficiency. So who is supposed to keep this system efficient, you are. It certainly was not designed to be efficient by itself.

Now add in scheduled maintenance replacement for lamps and ballasts. Given the poor lumen maintenance of the lamps, new lamps next to older lamps is readily discernable. Therefore entire banks are replaced whether they need it or not. This brings to question then, how many of these lamps actually reach full life since they don’t wait for them to burn out? This impacts cost directly in parts and labor to keep the system operating.

This is a system designed to be a maintenance headache from the moment it is installed to the day the building is physically destroyed. This is what I mean about True Cost of Ownership.

Incandescent lamps are no better than fluorescent given their short life spans. The basic life is measured by taking a group of 100 lights, turning them on, then measuring how long it takes for half of them to completely die. That number is the basic life of the lamp. The useful life is about 60% of that due to lumen loss over time. So a 1000 hour lamp is usually replaced in 600 hours due to lumen loss, not at the 1000 rated life. This means you will replace this lamp 100 times in the life of one Silescent fixture.

Now imagine a 30 foot ceiling with both of these systems installed needing constant maintenance. An auditorium is particularly bad since people would notice burnt out lights and flickering ones immediately. Color matching is imperative. Once the chairs are installed, just how easy is it to change the lamps or clean the fixtures? All these aspects affect Cost of Ownership. Now read the section to the left and see how a system can be created for zero maintenance.

The Silescent Light reduces the Total Cost of Ownership to a facility manager. The expected life is over 100,000 hours of operation. Assuming 10 hours of operation at full power every day of the year, the light will lose 30% of its initial lumen output in 27 years. The 30% number was selected based on a study that people working in a building did not notice the light loss until 30% was reached. It has become an accepted standard of life for LEDs.The Silescent Light will continue to slowly decay linearly until zero light output is reached. There is no filament to break or connection to corrode.The Silescent Light requires zero maintenance, there is nothing to replace. However, Inteltech recognizes the fact that after 27 years a facility manager may want to begin re-lamping the facility. A program may be instituted where the lights can be returned to the factory for re-lamping for a nominal fee, far less than replacing the fixture. Of course, by then who knows what will be possible.The lumen output of today’s LEDs is expected to double every 18 months for the foreseeable future. They already exceed the CFL in efficiency when compared fixture to fixture. This means in 27 years the only lights in the world will be LEDs. Are you sure you want to design a new facility with outdated technologies?

The right decision pays over time…

• Designing “Green”Designing “Green” means some hard choices must be

made. The old way of doing things must be abandoned for newer technologies. Newer technologies cost more because manufacturing volumes are low.

“Green” also means looking at the total impact our decisions cost us, society, and the natural environment. For instance, when choosing a lighting system based on mercury such as fluorescents, HIDs, Mercury vapor, HPS, etc. versus using a technology made from sand. Although the DOE attempts to explain the hazard away, it is still hazardous waste and must be dealt with by someone. We must pay for it’s safe disposal or recycling either through taxes, direct cost, or environmental impact. We must pay attention at all times where these products end up. Since our society is rapidly becoming one of no responsibility, no one pays attention and so they end up in our landfills.

SSL technology uses no toxic materials and is 98% recyclable. The aluminum fixture can be recycled if needed or simply re-lamped after 25 years.

System cost:• Initial component cost• Installation cost• Operational cost

• Energy cost Direct energyHVAC energy

• Ongoing maintenance• Component replacement• Labor cost

• Purchasing• Storage• Maintenance Personnel• Equipment

• tools• ladders• man-lift

• Add all these costs over the life of the building when comparing lighting technologies.

Green… at what cost?

• Energy Efficacy– A Fixture ComparisonA small candle0.1 Lumen/wattKerosene Lamp 1.4 Lumen/wattSmall fluorescent 2 Lumen/wattIncandescent (regular) 2.5-7 Lumen/wattHalogen 5-11 Lumen/wattCFL 35 Lumen/watt Silescent SSL (color dep) 26-47 Lumen/watt 4’ T5 (fixture dep) 35-50

Lumen/watt4’ T8 (fixture dep) 40-60 Lumen/watt

Traditional light made form burning fuels is quite low. People turning to the old ways, thinking they are saving the planet, are quite mistaken. Converting fuels to electricity and then to light is about 2000 times more efficient.

It’s fashionable to be “green” these days, but just how committed are we?

Some terms:Fixture Efficacy = Lumens Out/Power into FixtureLm/watt

System Efficacy=Total Lumens Out/Power into SystemLm/watt

Installation Fixture Cost=Components+installation

Long term recurring maintenance costs

AC vs DC Lighting Systems

• Efficiency vs EfficacyDesigners, engineers, contractors, building owners, and whoever

may in charge of the design, construction, and maintenance of a building need to understand the difference between Efficiency and Efficacy.

Efficiency deals with the ratio of Power In/Power Out. This usually has no units attached to it since watts are divided by watts and is a ratio. For instance, a power supply may be 90% efficient at converting power. The 10% is loss in heat and EMI radiation.

Efficacy defines efficiency between different units. For instance in lighting systems, the ratio is Total Lumen Output/Total Power Consumed is the System Efficacy. This is very difficult to measure in a building and must be calculated as the sum of the efficacies of each component. The total power in is also difficult to measure unless that power is solely used by the system.

Efficacy may also be specified for a single luminaire as the Total Lumen Output/Total Luminaire Power. This number takes into account the losses both in electrical power (ballasts and wiring) and lumen losses in the fixture due reflection and filtering. The luminaire must be tested in a laboratory to determine its total lumen output. If you change the bulb, you get a diferent value. Since bulbs and lamps come from many manufacturers, the value is really a “best guess”.

The mechanical part of the fixture has a lumen efficiency which is the Total Usable Lumens Out/ Total Lumens Produced (by lamp). Most fixtures range in efficiencies between 30-70%. Obviously, the less the light is reflected or filtered, the more light you will get. It is not sufficient to look at lamp/bulb lumen output numbers when designing a system, The fixture will determine the final lumen output.

AC lighting is the normal route most designers take. AC distribution uses high voltage, so it uses less copper per watt. However, AC systems suffer voltage loss just like DC systems. The longer the wire the more loss in voltage. Current is not lost in the wire, it uses up the voltage to get to its destination. Voltage dependent components such as incandescent lights will be visibly dimmer the longer the wire run.

DC lighting systems are Low Voltage. The maximum voltage allowed is 30 VDC. Wires limited to 60 watts maximum can be ran without conduit under Class 2 wiring practices by the NEC. Wires handling 60-1000 watts must be ran as Class 1 wiring, just like High Voltage.Silescent brings to the lighting designer a real low voltage solution. Each light contains a ballast which is 92% efficient at converting the power to drive the LEDs. The ballast also automatically adapts to voltage loss in the wiring so that each light is perfectly matched to every other light in the system. A large , remote mounted power supply can be used to provide multiple 25 amp circuits and act as a system power source. The power supply offers many advantages to the building owner and the power generation company.(continued)

Lamp Life Facts

• LLF (Light Loss Factor)A clean new fixture with a brand new bulb puts out the

maximum lumens the fixture will ever produce. It’s all downhill from there with standard lamps. The first loss occurs as the lamp gradually fades from initial lumen output to average lumen output over its life. The second loss occurs as the fixture and lamp get coated with dust and grime. Lights placed in areas where oils and grease are prevalent will lose even more lumens. Fixture and bulb cleaning directly affect light output and Cost of Ownership since someone must be paid to clean the fixtures. This gets very expensive when these fixtures are hard to reach.

Any high voltage source will charge dust particles. The strike voltage in most fluorescent systems is over 600 volts. The higher the voltage, the more dust will be attracted to the lamp. Think of the air purifiers sold to remove dust and particulates from the air. These units use very high voltages to the same thing.

A low voltage system will not charge the particles and therefore stay cleaner naturally.

A lighting designer must consider in his calculations at least a 10% loss of light due to dust accumulation on the lens and lamps (LLF). An additional 20% loss must be factored in to cover light loss due to aging of the lamp. This real lumen out is the average lumen output over the expected lamp life which is about 30% less than the initial fixture lumen output value.

For example, a 200 watt incandescent halogen lamp may put out 3200 lumens. The fixture optical efficiency may come in at 50%. This means that the lumens able to escape the fixture is usable light. The rest is lost to internal reflection. Now the lumen level is 1600 lumens. Now add in lumen maintenance or LLF factors of 30% and the lumen output is 1120 lumens. This is the real light level over the life of the lamp that this fixture will put out as usable light.

DC System Design

• DC Lighting and Power Factor Correction (PFC)Everyone is familiar with AC powered lights. Each AC powered Led light must convert the high

voltage AC to low voltage DC to operate. However, this process is complicated by laws limiting Current Harmonics and Power Factor. The laws are trying to reduce energy losses between the Power Generation Company and the Building. The technique for solving the problem is called Power Factor Correction (PFC). Current distortion is a different problem but the same fix solves both at once.

In an AC system each light must employ PFC circuitry to the ballast, this adds complexity which increases cost and reduces reliability (more components). The main problem is with the storage elements in the ballasts. For low voltage circuits, ceramic capacitors are used. For high voltage circuits electrolytic capacitors are used. The ceramics have a long life, electrolytics dry out and fail sooner. An AC ballast can be rated for 50,000 hours while a DC ballast is rated for 100,000 hours. The difference affects the Cost of Ownership of a system and must be factored in when deciding on AC or DC for your lights.

DC systems offers an alternative to each light needing the PFC circuitry. A remote power supply connects to the AC mains and converts the AC voltage to a DC voltage in one place. The power supply has the PFC circuitry built into it so the entire system appears as a resistive load to the Power Generation Company. This means the Current Harmonic Distortion and the reflected power are minimized which makes creating and distributing power more efficient. This helps the power company be efficient which translates to less oil and coal used to make electricity. PFC also helps reduce wire burn-out and transformer burn-out, thereby reducing maintenance costs for the building owner. These remote power supplies also provide immunity against brownouts and voltage dips. Each supply can operate from 85V-265 VAC and will provide consistent power to the lights over this input range. The supply also blocks any conducted noise to the power distribution system that may come from the lights. The lights will be rock solid with fluctuating AC power.

DC distribution is also inherently safer for everyone involved in installing and maintaining the system. You can literally grab the wires directly with no harm. This was not possible before Silescent technology produced lights with sufficient lumen output to be used to for general lighting. The Silescent Lights will scale from 600 – 5000 Lumens. Right now only 600, 1100, and 1700 levels are available.

The other reason low voltage DC is viable is the Silescent Light automatically adapts to voltage loss in the wires. It is unresonable to expect a electrical contractor to lay out the system always concerned about voltage loss. The adaptive nature of the Silescent Light allows the contractor to wire the system with the shortest paths possible with the heavy wire. He can create zones with the low voltage control wiring which is much smaller and more flexible, by connecting the control input together to make a zone. The control wiring is then returned to the control point rather than running power wiring to control points. This saves money by reducing the labor and component cost to the contractor. Hopefully, he will pass this savings on to the building owner.

DC lighting systems offer alternatives to design and installation unavailable to AC lighting systems. Let’s explore how to go about doing it.• First determine the lumens/square ft required for each area. Ceiling height affects light levels because light dissipates the farther it is from the light source. Beam angles and fixtures also act to focus light for specific tasks. Once the lumen/square ft is determined the number of fixtures can be calculated and their spacing in the ceiling determined.• Silescent Lights are grouped by their control wiring, not the power wiring. Size the power supplies to be 80% of the load. Assume that the power supply cost will be around $0.35 to $0.50/watt. Size the power wire to 12 gauge and use Class 1 wiring practices. Even though it is low voltage the possibility of fire is increased with the power levels involved (1000 watts max per wire).• If this is a large installation, contact Inteltech Corporation for assistance on the layout. We have software which can model your installation and optimize the time and costs required. The wire resistance of 12 gauge copper wire is 0.00187 Ohms/ft. Current flows in a circle and voltage is lost on both the feed and the return wire. 12 gauge wire is limited to a 20 amp breaker by NEC. The 80% rule should apply for the breaker, so consider 16 Amp loads flowing through the wire maximum design load. This means a 1000 watt, 24VDC power supply would feed two 12 gauge circuits or 3 14 gauge circuits. Since the lights will be attached at intervals along the wire, it is not a straightforward calculation as to the total possible length. (continued next page)

DC Installation Guide (cont)

Light Voltage Current1 23.57 1.612 23.23 1.643 22.37 1.704 21.83 1.745 21.28 1.786 20.74 1.837 20.19 1.888 19.65 1.93

It should be becoming apparent that each light appears as a different resistance to the power supply. Most lighting installations should have equally spaced lights and this method would work fine. Locate the power supply as close as possible where it is convenient for mounting and inspection. The distance to the AC breaker panel is not critical. The power supplies have universal AC voltage input ranges from 85-265 VAC and will adjust to whatever power is available. The supply will also maintain a constant voltage output at the output terminals. It is possible to adjust the supply to 30 volts legally to extend the wire run and allow a 14 volt drop. But this is the legal limit.

Let’s discuss a practical approach to designing your wiring runs, sizing your power supply, and choosing your wire size. One note here is that a breaker is used to protect a wire from creating a fire under a fault condition. A 12 gauge wire is protected with a 20 Amp breaker. Using the 80% rule for breaker loading, a lighting string may draw 16 Amps continuously without overheating the wire.

It is important to note that wire conducts electricity. Electricity is the flow of electrons through the wire. Voltage is the pressure which causes the current to flow from one end of the wire to the other. It is the voltage that is lost when currents flow in wire, the current is unaffected by wire resistance. Voltage loss is very important to calculate in a system since all electronic ballast are rated for an operating range.

The second point is that the voltages available from the power company have a operating range. The operating range for America is 105-132 VAC. A constant power device will draw less current at higher voltages and more current at lower voltages. This is same principle behind motors that must turn a loaded shaft. The motor will draw more current if the voltage droops. The reason is the load is unchanged and the same power is needed to turn the shaft.

Let’s assume a Silescent 200i light is spaced every 10 feet along the wire. The light draws a constant 38 watts at full power. Power equals voltage times current. The light is a constant power device and will adjust the current drawn from the wire depending on the voltage at the point where it is connected to the wire. This is very different from an incandescent bulb which will decrease its current draw if the voltage decreases. But this how the Silescent Light can produce equal light output with varying input voltages. Hopefully, you are beginning to see the differences.For example, if you have a 110 foot run of 12 gauge wire and placed at light every 10 feet, starting at 10 feet from the power supply, the total load lighting load would be 380 watts. The power supply would see this load plus the loss in the wiring. On the right is an example of typical voltage loss due to wiring and how the Silescent lights adjust for it.

DC System Design (cont)