Hey guys. I just went to troubleshoot a large grow room. Breakers are tripping for the 36 - 1000w HPS lighting. The building is 208v, the lighting is 240v.

I unplugged all the ballasts and fired up the breakers and contactors. Everything held and no tripping breaker. I tested voltage at contactors and receptacles, everything is 'OK'. I told the guy looks like hes got some bad ballasts.

I started plugging in 1 ballast at a time to try and find the bad ballast. Well come to find out every ballast is bad. Most are just not working, a few others pop'd, sparked and smoked. After the 2nd pop, spark and smoke I stopped.

Scratched my head for a few minutes.

Went back to test the contactors. I killed power to the coil and tested the contactors in the normally off position. There was voltage on the load side while the contactor was off!

I'm thinking the contactor failed and when it shut off it didn't shut off fully and must of sent 208v down a leg and fried the ballasts. Quite odd it happened to all 4 contactors.

Hes running these same contactors and same load in another room and its been fine for 6 months.

The stats on the contactor are: FL=40a, RES=50a. The load was 9000w of HPS lighting powered by an electronic ballast.

I told him his contactors are overloaded and basically welded together, creating 208v down 1 leg and destroying his 36 ballasts. $10,000 in damages. He had a hard time believing it, saying the contactors are rated for 50a and they shouldn't do that. I told him they should be rated atleast 20% higher... I was talking outta my ass at this point cause I really don't know.

Can you guys give your opinion on this and tell me the proper sizing for the contactors. Or maybe he needs a different type of contactor, idk. My contactor experience is little.

Trick:
It was a tough day today for me, but....

You said bldg. is '208' and lighting is '240'; is there any buck-boost transformers in the circuit?? Or are the ballasts on the 208 taps??

Get the info off of a ballast regarding 'operating' and 'start-up' amps, then check your ratings.

Did you clamp the loads on the contactors in the 'other room'??

How do you figure "208v down 1 leg"??

When you say 'grow room,' I start thinking of all manner of hackwork, using fixtures salvaged from dumpsters, to grow forbidden substances.

Please note that contactors carry a specific rating for HID lighting. An ordinary 'definite purpose contactor' is not rated for HID lighting.

Likewise, fixtures need to be supplied with power within 10% of their nameplate voltage. A "240" rated fixture is not suitable for use with 208v. Not every ballast is a multi-tap, or "automatic," especially with the old, obsolete HPS lights.

I'm sorry guys I'm more residential. I put my tester on it and it was 220v or somewhere in the 200s and I just jumped to the conclusion its 208v. Is there a 3ph high leg that is 220v?

I didn't test anything in the other room. The ballasts are from what I'm told 120 or 240 automatic. Same as in the other room. http://www.galaxyballasts.com/shop/...asts/galaxy-grow-amp-electronic-ballasts

Reno, they have a bit more than salvaged fixtures from a dumpster. From the new 1200a service, RTU and all the other gadgets I'd guess they have $200k+ into it.

To clarify when I tested any 2 legs gave me 240v. When I tested the legs to ground, 2 read 120v and the high leg read 210v+ (I'm not sure the actual number for this high leg I seen it around 208v it stuck in my head its a 208)

240V 3Ø has 2-phases 120V L-N, & what is supposed to be the B phase 208V L-N, any phase to phase should be 240V, 208Y/120V has
L-N of 120V, L-L is 208V just a note, a "slash rated" 120/240V breaker cannot be used between the high leg and any other phase, expensive 240V rated breakers have to be used.

Ok thank you for the clarification. It seems this is a Delta 120/240, 3ph has always confused me.

I'll have to check the breakers to see if its 240v rated breakers.

Do we think the improper contactors and possible wrong breakers could have fried the ballasts? Anything else I should investigate for this repair?

To my knowledge 240V rated breakers are only required where the high leg and another phase are being used for a 240V circuit.

Interesting link to the ballasts.....

$ 279.99 gets you a 240 volt, adjustable wattage, cord & plug connected ballast. The available info at the site, includes weight, dimensions, UPC #, but there is NOT one electrical piece of info. This would be the first 'cord & plug' connected ballast I have seen.

Is that a ballast for a double ended lamp?
I wonder if that is simply referring to the 410.30(G)(1) disconnect? (using a plug)

I'm sure the breakers are fine. The 'voltage rating' issue applies only to single-pole use.

The weak link is the contactor. To repeat myself, ordinary contactors are not rated for use with HID ("tungsten") lighting. Such lamps typically need a contactor rated for about 150% of what you'd expect from looking at the FLA.

A lighting contactor will specify 'ballast' and 'tungsten' load ratings. A definite purpose contactor will only specify 'resistive' loads.

Here's an example of a lighting contactor: http://www.schneider-electric.us/en/product-range/1864-type-l-lx-lighting-contactors/

Contrast that to the definite purpose contactor: http://static.schneider-electric.us...20Contactors-Class%208910/8910CT9301.pdf

Any place we know of to get cheap 50a lighting contactors? I need 16 of them.

Trick:

Why don't you check out Sq D Lighting contactors....

Check Reno's link above. They are made for lighting use and come in multiple # of poles within a single enclosure.

Did you check and verify the load amperages, both startup and 'run'??

Based on an 'Advance' replacement core/coil ballast spec
the start current is lower then the operating current.

I had to check this to satisfy my own mind.

Sounds strange that you have 16 'bad' contactors.

One thing I learned with contactors is going small or cheap is false economy. If you have anything but a toaster wire load, running at 60-70% rating is pushing it if these will make and break under load and you want a lot of operations out of them.

Greg:
There is about a $40 premium to go from a 50 amp, to a 90 amp, Sq D 2 pole, 240 volt coil DP contactor.

$$ from WWG list on the website.

I always went 'UP' on the rating as long as the physical size was OK for replacements.

Still, 16 "bad" contactors??

It was so far 4 contactors that went bad at the same time. Its a total of 16 through-out the 2 rooms that he wants changed so this doesnt happen again.

I'm going over there Thursday to move all the 240v breakers off the high leg. That is the only thing I can think that happened. The contactor went to shut off and only 1 leg shut off, leaving the high leg energized and killing the ballast.? Idk.

I had the previous electrician call me today and ask what happened cause the the owner wants him to pay $10k. Then right after the owner calls me and wants me to write a letter saying the damage was due to the previous electrician. I'm still confused I what actually happened here.

All I can 'add' is "careful with the letter"

Trick .... RUN AWAY!

There's no profit in being dragged into a dispute between thieves. Tell the customer that this job is outside the scope of your business. Send him a BIG bill - his failure to pay it will make him look bad, should he continue to try to drag you into this. Answer his inquiries with "I'm billing you for my efforts so far, there is no resolution, I have no idea what's going on, and am not comfortable proceeding."

I've seen far too many marginal customers seek out marginal contractors - whence the two each try to take advantage of the other.

Trick:

IMHO, I would not get involved with 'blame' unless you are 100+% confident that the 'problem' was related to the previous contractor. Confident enough to prove the cause, and that it was relative to the installation, or relative to the plans prepared by a Licensed Professional (Architect/PE/EE etc.)

It can turn quickly into a legal battle, and lawyers are usually the ones who profit from that.

Yup I'm not getting involved in any letters. I agreed to move any breakers off the hot leg and replace any currently bad contactors with whatever he supplies. He's paying cash, no receipt and I'm never coming back. I told him this and hes fine with it.

Thanks guys

If they're powering something using the high leg that could be the problem. Single-phase loads can't be fed by the high leg and the neutral.

That voltage will read 208V on a meter but that's just a mathematical coincidence; you can't put any load on that or you're going to have nothing but trouble. All you have available to you with that type of system is 240V-3phase and 2 places that you can get 120V-1phase from.

Also, the total of the single phase loads is limited to 5% of the transformer rating or you'll start getting overheating problems in the transformer ahead of the Service.

You don't understand high-leg 240/120V 3-phase 4-wire systems.

When you have 2-wire loads connected to 240/120V, the troubleshooting, and potential problems, are no different than any other 240V system. If you routinely hold hold one meter probe to ground, or neutral, the 'low leg' will be about 120V and the high-leg about 208V. It is straight math, if the high leg is not 208V, then the low leg is not 120V.

So, if one contact stayed closed, then one ballast wire would still be energized. At worst, the ballast would see 208V to ground, which is exactly the same voltage it sees when it is operating. How is this a problem?

The biggest issue is when the equipment uses a neutral connection. Unless you know the internal wiring of the equipment, do not wire it to a high-leg.

Bad contactor contacts can lead to abnormal currents. Abnormal currents can lead to device failure.

This whole thread confuses me. If the ballasts are plugged 240 and the building is 208 wye, where is the 240 coming from?
Aren't ballast 2 wire (single phase) loads anyway? If one leg was open, no current should flow no matter what the voltage is.
If this is really high leg delta, 240v between legs, you really have to be careful with single phase loads. They should never be on the orange (high)leg even if they are line to line 240v. If they are not perfectly balanced, you will get into trouble. That leg will drift around, depending on the load. We used to have that problem in computer rooms and the only fix, if you are not going to be scrupulous about load balance is to get the PoCo to drop in that missing 3d transformer. At that point they will want to hook you up wye anyway. I have really only seen one place with center tapped delta and 3 transformers (behind the Hogs Breath in Key West). I assume they grew into it.

Greg:
I've been scratching my head since page 1.

I used to do a lot of lighting maintenance in the day, both site lighting and interior. HID, fluorescent, etc.

Lots of contactors, both 'real' lighting contactors, and fabricated panels with definite purpose contactors. Never came upon anything like this.

Funny red leg though....one of my guys connected a 120 volt, single receptacle for a bottle type water cooler to the red leg. It took 3 coolers until someone said..."hmmmm"

Will this still be a problem if you somehow determine which of the 120V lines and the high leg the 2nd transformer is connected to? Idea being that your 240V load would be seen only by the 2nd transformer. Also this assumes that voltage drops in the wiring are minimal.

Yes.
Any time that you try to put a single phase load on the high leg you're asking for trouble.

All single phase loads, line to line or line to neutral should be on the "big" transformer, the one that is center tapped. The only exception would be if there are 3 transformers on the pole and that is rare.
Usually red leg delta is done with 2 transformers and if the load is not very well balanced, you will drag that 3d leg around and upset the 240/240/240 relationship.

If your distribution looks like this, be careful with your load balance

Just as gee whiz info, these are the transformers behind the Hogs Breath in Key West. The first thing that got my attention was that one was bigger than the other two and then I look at how they were connected. The fatter one is center tapped. This is the only time I have seen red leg delta using 3 transformers. My guess is the 3 bars it serves, does have a significant amount of single phase load and they fixed the balance problems or the load problem by dropping in the 3d transformer.