# Lighting Contactors



## dronai (Apr 11, 2011)

Replaced a commercial 12 pole contactors with some IEC type, and already had 2 poles fail (always stay closed) Lights burn 10hrs a night. The largest load is what failed, but I amp clamped it at 11.5A and 9.5A . The contacts are rated for 20A. 

The supply house thinks they failed because they are an Inductive load (Metal Halide) lighting, which is hard on the contacts. Says I should oversize them. Implying that I sized them wrong. I usually don't think of light as inductive loads, but they do have a large ballast in there, so I guess he's right.

What do you guys think, cheap contactors ? , or upsize them ?


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## wildleg (Apr 12, 2009)

some times there are other reasons why contactors fail. for instance, if a photocell is driving these and it is in a precarious place where it opens and closes the circuit 10 or 20 times or makes the chatter before finally closing, that could be the cause of early failure (happened to me anyways)


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## dronai (Apr 11, 2011)

wildleg said:


> some times there are other reasons why contactors fail. for instance, if a photocell is driving these and it is in a precarious place where it opens and closes the circuit 10 or 20 times or makes the chatter before finally closing, that could be the cause of early failure (happened to me anyways)


New T101 controlling.


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## McClary’s Electrical (Feb 21, 2009)

Buy nema rated


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## dronai (Apr 11, 2011)

mcclary's electrical said:


> Buy nema rated


 
That's what I think. That stuff looks like Legos junk !


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## Big John (May 23, 2010)

IEC when you know you can get away with it. NEMA if it just has to work. 

That said, the very first thing I check on premature contact failure is the control circuit. Chatter from low or intermittent control voltage will destroy a contactor (and the load) faster than anything else I know.

And generally speaking, if you get a lot of welding it's because you're seeing too high an inrush current for the contacts. Erosion will occur through excessive sparking, but to really heat and stick they've gotta be mated together and just shunting a ton of current. Got a part number off the contactor? Is rated 20A inductive? Does it have an AC rating number on it?


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## McClary’s Electrical (Feb 21, 2009)

dronai said:


> That's what I think. That stuff looks like Legos junk !


Honestly, I've used the same stuff. Is all about what you can sell the customer. They get what they pay for. I've been there too brother


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## dronai (Apr 11, 2011)

Big John said:


> IEC when you know you can get away with it. NEMA if it just has to work.
> 
> That said, the very first thing I check on premature contact failure is the control circuit. Chatter from low or intermittent control voltage will destroy a contactor (and the load) faster than anything else I know.
> 
> And generally speaking, if you get a lot of welding it's because you're seeing too high an inrush current for the contacts. Erosion will occur through excessive sparking, but to really heat and stick they've gotta be mated together and just shunting a ton of current. Got a part number off the contactor? Is rated 20A inductive? Does it have an AC rating number on it?



The right 12 pole contactor cost about $500. This was a cheaper route, but now I'm paying for it. This is in a existing metal enclosure with a wood back board


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## dronai (Apr 11, 2011)

This is what was in there before. Guy didn't want to spend the money


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## RIVETER (Sep 26, 2009)

dronai said:


> Replaced a commercial 12 pole contactors with some IEC type, and already had 2 poles fail (always stay closed) Lights burn 10hrs a night. The largest load is what failed, but I amp clamped it at 11.5A and 9.5A . The contacts are rated for 20A.
> 
> The supply house thinks they failed because they are an Inductive load (Metal Halide) lighting, which is hard on the contacts. Says I should oversize them. Implying that I sized them wrong. I usually don't think of light as inductive loads, but they do have a large ballast in there, so I guess he's right.
> 
> What do you guys think, cheap contactors ? , or upsize them ?


I like, and have installed "latch" relays and they work just fine.


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## Big John (May 23, 2010)

The contactors in there aren't suitable for the application. Where it says IEC operating current Ith (AC1)=20A? The AC number ratings are how IEC contactors designate the style of load, and category 1 is pure resistive.

So if you're gonna go the route of sticking with individual IEC contactors, either get ones rated at 20A of inductive load or grab the NEMA contactors which cost a lot, but the inrush and inductive loads are considered in the ratings.


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## dronai (Apr 11, 2011)

Big John said:


> The contactors in there aren't suitable for the application. Where it says IEC operating current Ith (AC1)=20A? The AC number ratings are how IEC contactors designate the style of load, and category 1 is pure resistive.
> 
> So if you're gonna go the route of sticking with individual IEC contactors, either get ones rated at 20A of inductive load or grab the NEMA contactors which cost a lot, but the inrush and inductive loads are considered in the ratings.


http://www.lovatousa.com/IEC-operating-current-Ith-AC1-/110010005/pl

Thanks, didn't know that, and I couldn't locate resistive or inductive on there like you see on Nema type.


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## Big John (May 23, 2010)

Yeah, a lot of the major manufacturers are good about just straight up telling you the types of loads they can tolerate, but if all you've got is one single current rating then there's gotta be more to the story. So look for that AC/DC rating code.


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## dronai (Apr 11, 2011)

Big John said:


> Yeah, a lot of the major manufacturers are good about just straight up telling you the types of loads they can tolerate, but if all you've got is one single current rating then there's gotta be more to the story. So look for that AC/DC rating code.


 
Thanks for that link, good stuff :thumbsup: AC-1 Resistive or Slightly inductive loads lol !!!


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## RIVETER (Sep 26, 2009)

Big John said:


> Yeah, a lot of the major manufacturers are good about just straight up telling you the types of loads they can tolerate, but if all you've got is one single current rating then there's gotta be more to the story. So look for that AC/DC rating code.


If you have a well connected set of contacts at the proper amp rating what does it matter if it is an inductive load or resistive. Just asking.


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## Big John (May 23, 2010)

The mass and surface area of the contact is different, for one thing. An inductive load going on line has a much higher initial current draw than resistive because of the inrush current, and when it goes offline it needs a higher interrupting rating because of the inductive kick. So you need a lot more meat in the mating surfaces of the contact assembly in order to prevent premature erosion or welding.

There may be other design considerations about trying to prevent contact bounce, or hardening the contact surfaces for high current loads and such, but I don't know enough about that to say.


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## dronai (Apr 11, 2011)

Seems like the IEC is for light duty applications.


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## Big John (May 23, 2010)

It is. IEC stuff is for very carefully engineered designs where you are certain you will not be exceeding the ratings and duty cycle of the device, and if you know that, the prize you win is they're cheap. 

The problem is that a lot of the real world don't work like that, and putting in IEC stuff just means that what you save up front in construction you waste down the road in repairs. 

When I've gotten away with IEC in the past it was either because I significantly over-spec'd it because that was still cheaper than the correctly sized NEMA counterpart, or else I knew it was in a very light-duty application where it would never see any abuse.


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## Jlarson (Jun 28, 2009)

Lovato :thumbdown:


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## dronai (Apr 11, 2011)

Jlarson said:


> Lovato :thumbdown:


:laughing: That supply house says they have no problems with it. I already had an overload block that kept tripping, with no load on it. They said I miswired it !


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## Jlarson (Jun 28, 2009)

Yeah Lovato is second on my list closely following Telecrap for most hated electrical product. 

BTW I don't think Lovato even recommends using the BG09 mini contactors for any MH switching duty.


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## oliquir (Jan 13, 2011)

i use fuji and eaton iec style contactor, but always 1.5-2 times rated HP or Amp and never had problems.


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## dronai (Apr 11, 2011)

oliquir said:


> i use fuji and eaton iec style contactor, but always 1.5-2 times rated HP or Amp and never had problems.


 

I was at just over double the Amp rating. 11.5A on a 20A ! What Jlarson said though.


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## Big John (May 23, 2010)

Double the resistive current rating ain't double the inductive current rating. I bet if you put a fast-capture meter on there you're drawing 100A through those things on inrush.


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## dronai (Apr 11, 2011)

Big John said:


> Double the resistive current rating ain't double the inductive current rating. I bet if you put a fast-capture meter on there you're drawing 100A through those things on inrush.


 
Learned something in this:


1) Never thought of any lighting as inductive. 
2) I knew about the ratings for the contacts, but thought I had a safe 
margin for continuous duty. 
3) Learned that IEC is cheaper for a reason.


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## oliquir (Jan 13, 2011)

oliquir said:


> i use fuji and eaton iec style contactor, but always 1.5-2 times rated HP or Amp and never had problems.


i forgot to say i normally check inductive rating and multiply by 1.5-2 times even for resistive loads


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## JDJ (Aug 9, 2011)

Curiously, Has anyone switched over to LED and found the need to change from contactor to solid state?


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## oliquir (Jan 13, 2011)

solid state and leds dont work well together if load is too small (under 1 amp for most solid state relay)


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