400W outdoor lighting help

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Old 02-21-09, 06:12 PM
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400W outdoor lighting help

Had qualified electricians install an outdoor light pole this week. It has two 400 watt fixtures on it. Manager said that until we can permanently connect the lights to a yet to be placed sub panel in the barn, we could run it off of our outdoor GFCI outlet.

Of course, the breaker tripped. Called to find out what the cut sheet said the Amp draw was... was told 3.333 per each lamp and he suggested I try at least a 20 if not a 30 Amp breaker.

20 Amp no good, can't replace with a 30 Amp, so we decided to go ahead and run a permanent outlet off of the 50 Amp service we have pulled for the sub panel in the barn. Lights came on, no problem. Stayed on for about 30 minutes and then the 20 Amp rated GFCI outlet fried.

So, three questions: Why do 6.666 Amps require such a large breaker?
Can I get a 30 amp rated GFCI outlet, or do we need to rethink this? Why would the 20 Amp rated one fry?
What else am I missing? Do I need to have a heavy duty wire running to the outlet as well?

No longer trust the advice of my electrician......
 
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Old 02-21-09, 06:19 PM
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Are you saying you have a 50amp breaker going to a standard GFCI outlet?

This is a major fire hazard.

What is the size of the wiring going from the lamp back to this outlet?

How many other things are on the same circuit as this GFCI?
 
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Old 02-21-09, 06:52 PM
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How long of a run is it? Depending on that, seems like another issue. As stated although temporary, not a good idea to exceed the wire ampacity.

I came up with 4.2 amps each for a 400 watt MH. But still it should be ok.

Why can't you pigtail to the GFI, instead of feeding the lights off of it, it doesn't need to be GFI protected.
 
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Old 02-21-09, 09:50 PM
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The standard 400 W Metal Halide luminaire typically draw 4.2 amp at 120V unless your electrician screw up the multitap connection at the ballast it should not affect the GFCI at all.

I will sugget that if that electrician did use 50 amp breaker that is a major no-no on that one.

Have the electrician check the system wiring and the ballast it should not draw more than 4.2 amps running if more than that you have bad capaitor or ballast going bad that two most common failure on them.

And double check the bulb too to make sure it is a correct bulb in there it should match the ballast rating there.

Did those 400 w MH floodlight do have a stand by bulb in there sometime we call them AUX bulb they only come on when it is cold or during restrike mode depending on the set up.

And the distance and conductor size it may affect the performace of them.

Merci,Marc
 
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Old 02-22-09, 05:29 AM
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HOTINOKC--currently we don't have ANYTHING set up, as nothing seems to be working, hence submitting a post here. We were trying to create a new outlet for the 50 amp service for the outdoor lighting, since our previous outlet kept throwing the 15 amp breaker. Eventually the 50 amp service will support a sub panel in the new building, and the lights will be hard wired to the panel. Looking for a temporary solution that's safe.
Will check the wiring on the lamps, but it ends in a basic three prong plug which I have connected to an exterior drop cord to stretch across the yard and plug in somewhere at the house.
No other items on the circuit.
 
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Old 02-22-09, 05:33 AM
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WIRENUT--The run from the junction box the 50A service is terminated in is about 5' to the exterior wall where we've placed an exterior rated box/outlet. Need to figure out what the correct rating is for the wire from the termination box to the outlet, and the correct rating for the outlet. We had placed a 20A GFCI in the box as an outlet b/c I'm concerned about drop cords and the exterior location. Outlet fried when lights where plugged in after about 30 minutes.
From the exterior outlet to the base of the lights, we have about 50' of exterior drop cord the lights are then plugged into.
Didn't understand your comment about pigtailing the lights into the GFC? Speak/write slowly.....I'm definitely ignorant :-)
 
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Old 02-22-09, 05:41 AM
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Marc/French227V--Bonjour et merci beaucoup pour la reponse.
So, stupid question here, can I add the 4.2 + 4.2 and assume that the lights are drawing 8.4 amps? Do they draw slightly more at start up?
If they're only drawing 8.4 (and my guys say it's 6.6 based on the cuts) why, when I plugged them into my standard exterior GFCI outlet, do they trip the 15 A breaker in the panel when nothing else is on that's tied into that circuit? If they're brand new, how likely is it to find a bad capacitor or ballast?
 
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Old 02-22-09, 06:13 AM
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Never mind the pigtail since you're plugging them in. I thought you were hard wiring them off the GFI.

Yes, you should be seeing around 8.4 amps.
Yes, it is possible to have a defective ballast (someone bought it, smoked it, brought it back and said they didn't need it) Is why I tell my people ,DO NOT buy anything that appears to be opened/resealed.

As stated, one or both are just wired wrong. If possible, hook one light up at a time and see what happens.
 
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Old 02-22-09, 12:25 PM
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KawKaw.,

Did you say 6.6 amp ? the reason why someone goof up with all the HID and Flourscent luminaire we don't go by lamp wattage we go total system wattage or amp rating to get the correct figures.

and most common 400w HIDs typically run at 4.2 amp { some will draw less it all depending on type of ballast to use }

Go with Wirenut's way it will be the same way I will tell ya.

run each luminaire it own to make sure it is not tripped or overloaded

There are few ways it can go bad as Wirenut stated

Bad ballast
Bad capitor
Bad conductor { pintiched }

Merci,Marc
 
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Old 02-23-09, 05:38 AM
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Thanks everyone for the helpful advice!
 
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Old 03-09-09, 10:15 AM
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update on lighting, still confused....

Okay, one blown bulb, and one lamp that checks out okay, so it's not the lamps.

Installation crew tells me today that the lamps are drawing, together 24 amps on start up, then settling in at the 6.66 amp (combined) load when warmed up.

The have recommended that I hard wire the lamps to my 50 amp service that I plan to use for the subpanel in the barn. They tell me that the 12 gauge wire they have on the lights is fine for the lights and to wire to the 50A service, and that I don't need a GFCI as I have a 50A breaker, and can direct bury.

I can't put my finger on it, but 50-24= 26 worries me, as does the 12 gauge with a 50A potential load if something goes wrong...

What do you do when your electricians are telling you something wrong other than hire another electrician??
 
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Old 03-09-09, 11:06 AM
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#12 AWG wire should not be connected to the 50 amp breaker. Get those lights off of the GFCI. The 50 amp breaker is in the main panel, correct? If so, remove the 50 amp breaker and install a 20 amp breaker to feed the MH lights.
 
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Old 03-09-09, 11:36 AM
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20 amp breaker was tried previously on another circuit and tripped
 
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Old 03-09-09, 09:44 PM
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Can you tell me what manufacter the luminaire you have and the ballast manufacter it is ?

Something is not adding up right.

for two 400 watts MH luminares on 20 amp circuit the breaker should not trip at all.

Most 400's what I conferaged on 120 volts on 20 amp circuit the max is 4 luminaires and not even get the breaker tripped.

If you have Advance ballast let me know the number I can able double check if other brand name just run the model number and I will dig up the info.


Again as I mention above do not run #12 awg conductors on 50 amp breaker that is nuts you need to use the correct 20 amp breaker otherwise get High Mangatic breaker or HID rated { most modern breakers are switching duty but some will have HID rated some not so if that the case you will have to order the HID ratied breaker I know they cost little more than standard breaker but it worth it }



Merci,Marc
 
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Old 03-10-09, 08:17 AM
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WOW! Something here doesn't add up. There has to be a wiring issue. I know the ballasts are multitaps and something has to be wired wrong with these. Check as wirenut wanted, do 1 light at a time and check the draw. If I remember correct you had 1 blown light ( Why ). You have a set of wires for that ballast with different ranges of voltage. Are they wired correct? If so do you have the wires that aren't being used taped off so they can't short out to anything? I'm just throwing out so ideas good or bad. A 20 amp breaker should hold 4 of these lamps. I'm going to think on this. As stated before, don't hook this up to a 50 amp breaker.

Jim
 
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Old 03-10-09, 02:02 PM
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Dude, you need to troubleshoot the circuit. Connect one fixture at time to the circuit breaker. Turn it on and see if the breaker trips. No trip? Do the second fixture. Process of elimination is the only way to go in your situation.

AS ALWAYS: BE CAREFUL!
 
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