help with a lighting calculation

Status
Not open for further replies.
R

rickl

Senior Member
hi
this local race track called me to look at some problems there having with one area of the track lighting and the panel feeding these lights( breakers tripping, breakers burning up and finally the main breaker burned up). all the other lights of the track are feed from disconnect and are working fine. so the first step is a calculation 46, 1500watt halogen outdoor lights = 69000 va x 1.25 = 86250 va/240 volts = 360 amps. Does this look and sound right? it doesn't to me. if thats right each light will draw 6.25 amps? i would love to be able to look inside one of these light but there mounted on 65' poles. What they want to do is replace the existing 200 amp panel with a 225 amp panel and if my calculation are right this isn't going to help them at all. they will need a 400 amp service or turn off half there lights. any help or insights would greatly be appreciated thanks
 
Re: help with a lighting calculation

Your calculations look pretty good.

I think 150W HPS heads pull an amp at 240, so a 1500W would be a considerable load, over six sounds right. Add 45 of his friends and you've got a party.

How many circuits are involved?

[ February 23, 2005, 08:51 PM: Message edited by: georgestolz ]
 
Re: help with a lighting calculation

i'm about 99% sure its 120/240 volt system.its an old panel no markings, i had to look at a breaker to find out it a siemens panel, didn't think to check voltage. its single phase and there is 5 circuits 2 feeds 10 lights each, 1 feeds 6 lights,1 feeds 4, 1 feeds 16. when i was there my meter read 165 amp with all the breakers on. wait a minute that calculates closer to 480 volts than 240 volts i'll have to so more investigating. from what i was told this little electric room feed everything on there property i only seen 1 transformer, it was one on those fast tour on the property showing me about 10-12 things that needed fixed or not working, it was a very scary 30 minutes
 
Re: help with a lighting calculation

Originally posted by rickl:
it was one on those fast tour on the property showing me about 10-12 things that needed fixed or not working, it was a very scary 30 minutes
Click to expand...
:D

Well, do some scouting, keep us posted. This sounds interesting! :D
 
Re: help with a lighting calculation

Are you sure the lamps are halogen and not HID. With poles at 65 feet and the short life of quartz halogen lamps somebody must be doing a lot of pole climbing to replace lamps.
 
Re: help with a lighting calculation

Are you sure the lamps are halogen and not HID


thats what i'm told, they rent a manlift one a year to change lamps
what does HID stand for? and what do they look like? i've herd of this type of light but never worked on them. from the ground the lights look like halogen,
 
Re: help with a lighting calculation

:D

Edit to add: From the ground, looking at the head of a flood 65 feet above is pretty inconclusive. They are probably HID lights. But the draw still sounds pretty close for 1500W fixtures.

I'd say this is going to involve trenching. But keep us posted! :D

[ February 24, 2005, 07:37 PM: Message edited by: georgestolz ]
 
Re: help with a lighting calculation

i've always wondered what HID lighting was refurring too now i know. retraction i have worked on HID lighting before just didn't no it.
 
Re: help with a lighting calculation

You cannot simply take lamp watts, and convert to VA to find the amperes for a HID lighting load calculation. The input amperes of the ballast must be determined somehow, preferably by getting data for the actual ballast in use. Typically, the VA input is greater than the lamp watts; the ballast is not 100% efficient, and the power factor is less than unity. I checked in one ballast book, amp draw is 6.8 or 7.2 amps at 220 depending on the model selected, single voltage or multi-tap. Also, most will use regulating ballasts that handle +/- 10% voltage variation for long runs and tall poles, so the system may have been sized for more than usual voltage drop, making the amperes even higher.

Another thing to consider is the inrush on HID fixtures, there is a large capacitor installed with the ballast for starting, add all of these up and you get major current inrush for the first 1/2 cycle. This inrush can easily damage devices not designed for the application, which is why you see a lot of switches and contactors with separate (and lower) HID ampere ratings. I've also seen stuff burn up prematurely because the control voltage to a switching contactor would drop too much on inrush, making the contactor bounce or chatter, which has the effect of repeating the inrush multiple times on each switching action.
 
Re: help with a lighting calculation

update
just got back from the track, the lights are 1500 watt halogen. there's 36 not 46 lights coming from the 200 amp 120/240 volt panel. the reason i only got 165 amp the first time was 1/3 of the lights are burned out. what a mess, whats the best way to calculate 2 concession stands ones is 10x10 just candy, popcorn. the other 30x10 pop, freezer, refrig,and all the cooking is gas. it has a 200 amp service to the biggest stand then a 100 amp sub coming out of the 200 amp panel feeding the small stand.there also building a new crows nest ( small building overlooking the track )i would like to feed this from the 200 amp panel too. there will be 1 flourescent light, a couple of receptacles, one will feed the amplifier for the load speaker, i have no idea about what the amplifier would draw? what size sub panel would you recommend i'm thinking 30 amp minimum maybe 60 amp if it won't overload the 200 amp
thanks for the help i better hit the books
 
Re: help with a lighting calculation

Can you clarify your racetrack lighting situation?

Remember, regarding the other items, it's not the size of the panel, it's the load it bears. :D

[ March 03, 2005, 07:56 AM: Message edited by: georgestolz ]
 
Re: help with a lighting calculation

problem 1: they have 36, 1500w 240 volt halogen lights on a 200 amp panel (36 x 1500= 54000va x1.25 = 67500va / 240 volts = 281 amps) the panel is overloaded when all the lights are on. so i need to take some of the load off the panel.
problem 2: the 200 amp disconnect feeding the concession stands also feed the crows nest and 10 halogen light they came off the secondary of the disconnect with 3 wires under each lug ( 4/0 alum,#2 copper,#6 copper) so that will have to be changed. thats why i'm thinking of feeding the crows nest out of the concession stand 200 amp service. plus the #2 copper feeding the crows nest leaves the disconnect 4 black wires but comes out of the ground 100' away 2 black & 2 white wires so there spliced underground somewhere.and i don't want to be liable for a underground splice i didn't do.

i hope this makes sense to everyone thanks
 
Re: help with a lighting calculation

ricki,
Sounds like a lot of heat at this panel. The heat may not be coming from the load but simply loose connections at the breaker, at the main braker, or from the source of this feeder.
Always do an actual voltage check with load on. If voltage is low, amps go up. E over I times R. 33 yrs has taught me 98% of burned up breakers etc. is loose connections
Does this panel have bolt-on breakers? I would hope so.
 
Re: help with a lighting calculation

its a sieman panel breakers slide in, you don't think 281 calculated amp is something to worry about?
 
Re: help with a lighting calculation

I am totally confused about how much load you really have on this panel. But, if a loose connection was not present the breakers would simply trip on overload. The statement about AL and CU on same breaker still points to bad connections. Only heat generated from bad terminations ; line or load side; should cause meltdown as stated.
 
Re: help with a lighting calculation

the copper ,alum wire mix was a different problem that was coming off a 200 amp fused disconnect, they not having problems with that. when i first looked at the job, thats what crossed my mind was poor connection and a old panel, but now i think as the breakers tripped they just put a bigger one in, in the panel they have a 125 amp breaker with # 6 alum coming off it and 2 100 amp breakers with the same wire, what i recommended on doing was changing out the panel with a new one but after a load calculation i don't think thats going to help the problem with overloading
 
Re: help with a lighting calculation

I read everything you write as though you're out of breath. :D
what a mess, whats the best way to calculate 2 concession stands ones is 10x10 just candy, popcorn. the other 30x10 pop, freezer, refrig,and all the cooking is gas.
Click to expand...
For your purposes, I'd say looking at each piece of equipment and determining the actual connected load is your best bet. Might take a while but it will wipe a lot of gray out of the problem.
problem 1: they have 36, 1500w 240 volt halogen lights on a 200 amp panel...the panel is overloaded when all the lights are on. so i need to take some of the load off the panel.
Click to expand...
So put in a larger panel. Address each problem in order. Install a bigger panel, then: Are the conductors supplying it big enough? Replace them, on down the line. I view their changing breakers out for larger ones as a sure sign the circuits are undersized for the load.

It really sounds (from this distance) like you're going to wind up replacing a few panels, digging new circuits to the lights, and replacing a lot of conductors that have been overloaded. From my seat. :D

I would clear things up for us, if you wrote up a schedule of what's feeding what, how big they are and what the connected load is. As in:

200 Amp Service feeds...
*200 Amp Panel A, which feeds
**100 Amp Panel B
**060 Amp Panel C

Panel A's connected load is...
1 50 amp BC (#6 CU) supplying 62 amps connected load
1 30 amp BC ...

Panel B's connected load is...
Click to expand...
I think you'll see the answers start jumping out at you if you sit down and write it out like that. Just a thought. :D

[ March 04, 2005, 08:08 AM: Message edited by: georgestolz ]
 
Re: help with a lighting calculation

thanks george for the advice,
(Address each problem in order) thats kinda what i tried to do but every solution to the problem created another problem or wouldn't fit in the building 4'x4'x6' high. so what i think the best plan would be to install a new 200 amp service to the outside of the building , one of those combo meter with 8 circuits and refeed 22 lights out of it, then replace the old 200 amp panel and refeed the other 24 lights out of that.
then the next problem is the 50kva transformer big enough for all the lights, what i figured 78 lights most are 1500 watt halogen = 117kva. the lights are only on 2 to 4 hours, 1 or 2 nights a week during the summer. the problems just keep coming and coming :)
thanks again
 
Re: help with a lighting calculation

Why not just forget upgrading the electrical service and make the customer more happy with lower energy bills. Replace the Halogen light fixtures ( 35,800 lum initial light output - 2,000 hr life) with Metal Halide light fixtures (150,000 lum initial light output - 3,000 hr life). Use much less light fixtures with much less amperage. Many light fixture manufactures will take your layout and give you the number of light fixtures with aiming info at no cost. With present energy costs - halogen lights should be replaced as payback is often quick (probably 1 to 2 years max for this job.) Doing otherwise is just a waste of money.
 
Status
Not open for further replies.
Top