# General Question



## JDHElectric (Oct 7, 2010)

we are looking at doing a lighting retro fit in a 115,000 sq ft manufacturing facility. this facility is probably 40 years old and they have added lighting panels everywhere which they want to get rid of and install only one or two main lighting panels. They have the service available to do this with 2 575v 2000amp services and another 575v 600a service. 

for t5s we are looking at 96,688 watts for 409 fixtures

my thoughts are to install these at 480 or 277v

480 load i believe would be 120a 
277 load would be 200a 

please check my math.

what do you think? also, i have not installed lighting at 480v before, are there restrictions on this that i need to know about?


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## MDShunk (Jan 7, 2007)

I'm coming up with a funny number when I divide 96688 by 409. Did this wattage total include the ballast?


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## JDHElectric (Oct 7, 2010)

yes it does include the ballast


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## JDHElectric (Oct 7, 2010)

I also just rounded up the decimal instead of the long #. The wattage is very close


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## Dennis Alwon (May 9, 2009)

You may want to read this.



> 250.97 Bonding for Over 250 Volts.
> For circuits of over 250 volts to ground, the electrical continuity of metal raceways and cables with metal sheaths that contain any conductor other than service conductors shall be ensured by one or more of the methods specified for services in 250.92(B), except for (B)(1).
> Exception: Where oversized, concentric, or eccentric knockouts are not encountered, or where a box or enclosure with concentric or eccentric knockouts is listed to provide a reliable bonding connection, the following methods shall be permitted:
> (1)  Threadless couplings and connectors for cables with metal sheaths
> ...


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## Dennis Alwon (May 9, 2009)

JDHElectric said:


> yes it does include the ballast


Just the ballast and not the bulbs-- correct?


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## JDHElectric (Oct 7, 2010)

that wattage is ballast & bulbs


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## JDHElectric (Oct 7, 2010)

Dennis, the customer wants to use reloc so as to save us running so much conduit I dont really see anything in that article that would prohibit that at 480v unless Im reading incorrect

right now the place is full of end to end 8ft t12s, virtually no conduit for the lighting, its all through the fixtures


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## Dennis Alwon (May 9, 2009)

JDHElectric said:


> that wattage is ballast & bulbs


You only need to use the ballast amperage-- forget the bulbs.


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## Salvatoreg02 (Feb 26, 2011)

Dennis Alwon said:


> You may want to read this.


So? You get a panel enclosure without ko's and drill them out yourself.

Sent from my iPhone using ET Forum


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## Rockyd (Apr 22, 2007)

Dennis Alwon said:


> You may want to read this.


 
??? So? Same rules apply to all the 277 we run.

I was thinking that 210.6 (C) & (D) might be more of a concern if greater than 277.

Edit - thought he might be looking at something beyond florescents....


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## Dennis Alwon (May 9, 2009)

Rockyd said:


> ??? So? Same rules apply to all the 277 we run.
> 
> I was thinking that 210.6 (C) & (D) might be more of a concern if greater than 277.


Not sure where (D) comes in to play since that is 600V between conductors.


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## BBQ (Nov 16, 2010)

Rockyd said:


> ??? So? Same rules apply to all the 277 we run.
> 
> I was thinking that 210.6 (C) & (D) might be more of a concern if greater than 277.


480 grounded delta would be an issue, 408Y/277 is not a problem.


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## JDHElectric (Oct 7, 2010)

Dennis, how can you only factor the ballast amperage for the load? The lamps are part of the load, am I missing something?


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## Rockyd (Apr 22, 2007)

JDHElectric said:


> Dennis, how can you only factor the ballast amperage for the load? The lamps are part of the load, am I missing something?


See 220.18(B) 
*(B)* *Inductive and LED Lighting Loads.* For circuits supplying lighting units that have ballasts, transformers, autotransformers, or LED drivers, the *calculated load shall be based on the total ampere ratings of such units and not on the total watts of the lamps*.

Which is a lot more accurate in definitive load than what is being put out at 220.14(D)


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## JDHElectric (Oct 7, 2010)

Rocky, thanks! Usually we don't have to do the "calculations" for these projects but this particular one we are having to.. This is why I ask the best electricians there are on this forum...I love knowing that I don't know it at all and am always learning


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## JDHElectric (Oct 7, 2010)

also though as I think about it, don't you have to figure in the lamps at some point, I mean what if they are all on at the same time? won't this overload the system?


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## Dennis Alwon (May 9, 2009)

Simply put the ballast rating takes into effect the actual load. The lamp load would be close but not accurate. If you did the lamps and the ballast then you would have almost double the load you actually would see.


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## JDHElectric (Oct 7, 2010)

Ok so this is how I figured, if anyone cares to check my math I appreciate it.

The fixtures are 4 lamp 54w t5 the input wattage for each is listed as 236.4
there are 409 fixtures to be installed

i figure at 120v this is 470A and 15 lights per ckt installing 30 ckts
277v this is 200A 17 lights per ckt and installing 25 ckts
480v this is 120A 30 lights per ckt and installing 15 ckts

just want to be pretty sure as this is about a $150K retro fit with all material, labor, recycling, etc.

Thanks in advance for your help


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## Dennis Alwon (May 9, 2009)

If the ballast is rated 236v how are you hooking it up 277 or 480v. What is the ballast amp. It will be written on the ballast. Is there 1 or 2 ballast per fixture.


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## JDHElectric (Oct 7, 2010)

236 is the input WATTS per fixture not voltage. They are 1 ballast each


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## Dennis Alwon (May 9, 2009)

So if there are 409 fixtures at 236.4 watts each that would be 96,687.6 watts.

watts/volt = amps

96688/120 = 806 amps that is 269 amps per phase assuming 3 phase

@ 277 it would be 349 amps at 116/ phase


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## Dennis Alwon (May 9, 2009)

Also at 1.97 amps per fixture you can only get 9 fixtures on a 20 amp cir.

20 amps= 2400 watts*.8 for continuous load = 1920 watts


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## JDHElectric (Oct 7, 2010)

2400 watts? thats only for 120v right?

if you increase the voltage the amperage goes down so you would be able to get more fixtures on a 277 or 480 ckt right?


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## Dennis Alwon (May 9, 2009)

JDHElectric said:


> 2400 watts? thats only for 120v right?
> 
> if you increase the voltage the amperage goes down so you would be able to get more fixtures on a 277 or 480 ckt right?


That's correct. 20amps * 120v = 2400 watts
20 amps * 277 = 5540 watts

For continuous load take 80%.


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## rdevarona (Feb 23, 2010)

JDH,

Just one small point... Remember to take into account the price difference between 277V and 480V T5HO ballasts. In my experience, the 480V ballasts aren't as readily available as the 277V 4 lamp T5HOs. 

Regards,

rdv


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## Rockyd (Apr 22, 2007)

rdevarona said:


> JDH,
> 
> Just one small point... Remember to take into account the price difference between 277V and 480V T5HO ballasts. In my experience, the 480V ballasts aren't as readily available as the 277V 4 lamp T5HOs.
> 
> ...


Thanks.
Couldn't remember if they made a 480 ballast or not....:whistling2:


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## Electric_Light (Apr 6, 2010)

240VA ea, give or take. From the wattage you gave, its gotta be a 4 lamp.
Demand: ~100kVA. Assume you get them spread out evenly across all phases.

100kVA/0.48kV/(sqrt 3)/0.8 =150A per phase.

Each pair of wires going to light needs to be 33.33kVA/0.48kV/0.8 = 87A and every control device needs to be two pole, 480v rated.

It's still going to be 150A per phase at the service using 277v if its coming from 480Y/277v and you're spreading the load evenly across, but, each set of wires going(N + phase) will handle full 120A(150A, but derated to 80%) , but can be controlled with single pole 277v rated devices. 

Wires to handle more current for each phase cost money, but so do 480v switchgear and ballasts, not to mention 480v ballasts are hard to come by and they're usually 480v only. Almost all commercial use ballasts are dual rated for 120 and 277 and most allow use at anything in between such as 208 and 240. Since 120v is also a common voltage and one ballast works for both voltages, they're stocked much more commonly. 

Does that look about right?

On a N-Ph system, if you blow a fuse, you'll lose 1/3. On a Ph-Ph system, if you lose a phase fuse, you'll lose 2/3. 



JDHElectric said:


> we are looking at doing a lighting retro fit in a 115,000 sq ft manufacturing facility. this facility is probably 40 years old and they have added lighting panels everywhere which they want to get rid of and install only one or two main lighting panels. They have the service available to do this with 2 575v 2000amp services and another 575v 600a service.
> 
> for t5s we are looking at 96,688 watts for 409 fixtures
> 
> ...


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## kaboler (Dec 1, 2010)

575v? Did you check the voltage at the panel? In canada we have 347/600, and 347 ballasts are more expensive, but way more awesome. 347 being 1 phase.

How about contactors?

As for what Dennis says, just imagine running 347v. 

Dennis @ 120v:
20 amps= 2400 watts*.8 for continuous load = 1920 watts 

347v:
20 amps=6940 watts *.8 for continuous load = 5552 watts.

Could easily get 20 fixtures on 1 circuit. (why max it out)

Big places COMMONLY have 347 and it suprises me when they aren't running at 347.


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## nitro71 (Sep 17, 2009)

Definetly go 480 volts if you have the option to. Less amperage. Less number of circuits. Still 277 to ground. Same as if you go 277 volt lighting. Except you get to drop the neutral. I'm sorta tired or I'd crunch the wattage. Sounds like a fun job.


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## kaboler (Dec 1, 2010)

nitro71 said:


> Definetly go 480 volts if you have the option to. Less amperage. Less number of circuits. Still 277 to ground. Same as if you go 277 volt lighting. Except you get to drop the neutral. I'm sorta tired or I'd crunch the wattage. Sounds like a fun job.


Yeah, that's awesome too. Mindless work not even caring about a neutral. I once got to do a 208 lighting retro and hahahaha, it was awesome. Not that matching colours is particularily hard.


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