Help with Heating wiring

[tboltkc]

I'm new to the forum but it has come up in a lot of searches as I try to get my shop setup. What a great place!

I just got my shipment of 3 infrared heaters with line voltage thermostat and contactor panel (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250019686670&sspagename=STRK:MEWNX:IT&viewitem=) and need some help on how it should be wired up.

The heaters are of course 240 volt, the contactor panel is 60 AMP 3 pole and the thermostat is 22 amp, 125, 250, 277 VAC (according to the box).

I don't quite understand how to hook it all together. Do I need one circuit for the thermostat (110 would do?) that connects to the coil in the contactor? And then the 240 circuit that goes from the breaker (would 40 amp be enough or do I actually need bigger) to the L1-L3 terminals on the contactor, then from the T1-T3 terminals on the contactor to the heaters? This is what I've gathered from my searching the web, but I feel like I'm missing something.

Any help would be greatly appreciated, I'm sure this seems like a simple setup for many of you, but this is my first time wiring anything like this. I have run the rest of the wiring in my shop for lights, outlets, etc but can't get my head around this.

-Travis

 

[Aceman]

I'll make this quick, I'm short on time.

4 circuits total needed:

one 120v 15 amp circuit for the line stat switching the coil(I assume 120v coil?) on the contactor.

three 240v circuits, one for each of the heaters. Run from the panel to the contactor box, each pole of the contactor will break one leg of each heater circuit. Then from the contactor box to the heaters.

You need a disconnecting means on the heater circuits if the panel isn't within site of the heaters. I usually use a breaker lockout because they're cheap if a disconnect is required.

 

[tboltkc]

aceman - thanks for the quick reply.

The contactor actually has a 208/240 volt coil. And I thought part of the purpose of
using a contactor panel was so you didn't have to run a circuit to each unit? Or is it purely a control/relay?

FYI - each of the heaters is 12.5 amp at 240V, and the contactor is rated for 60 amp (just looked at one of the heaters).

 

[vinculum]

Just for kicks, I suggest you temporarily hook up one heater and test it out before going through the trouble of wiring up the contactor. I used 12 romex and a single 20 amp breaker.

The thermostat you have is designed to directly control a single heater if you wish (240v @ 22 amp rating)

Of course you could skip the contactor and just turn them all on and off with individual breakers. In my garage the thermostat would never toggle on and off anyhow, because they put out so little heat.

Dr V

 

[Aceman]

Just for kicks, I suggest you temporarily hook up one heater and test it out before going through the trouble of wiring up the contactor. I used 12 romex and a single 20 amp breaker.

Why do you want him to temp. wire it?

The thermostat you have is designed to directly control a single heater if you wish (240v @ 22 amp rating)

He has 3 heaters and one thermostat that doesn't have the capacity to run them all simultaneously, so I don't understand what you're getting at?

Of course you could skip the contactor and just turn them all on and off with individual breakers. In my garage the thermostat would never toggle on and off anyhow, because they put out so little heat.

Again, you're entire post is confusing. Why would he use breakers for switching(they're not made for that) when he already bought a thermostat and contactor setup? That doesn't make sense?

aceman - thanks for the quick reply.

The contactor actually has a 208/240 volt coil. And I thought part of the purpose of
using a contactor panel was so you didn't have to run a circuit to each unit? Or is it purely a control/relay?

FYI - each of the heaters is 12.5 amp at 240V, and the contactor is rated for 60 amp (just looked at one of the heaters).

Your best bet is 3-20 amp 240v circuits using #12 wire, you will not need the 120v circuit for the coil power that I mentioned earlier. Tap off one heater circuit in the contactor box, run this to the line stat and then back to the coil. If you try to lump all the heaters together into one circuit that'll require #6 Romex, then you have to figure how you'll splice those big wires, it requires more junction boxes, etc.

 

[tboltkc]

aceman, thanks again. I understand now.

Dr. V got these same heaters and wired one temporarily to see how they work and wasn't thrilled, so he's just suggesting that I try that before going through all the trouble. With this type of heat, recovery is not good. I get that and plan to leave them on all the time (lowest setting) and possibly use a supplementary source for quick warm up if necessary. His thermostat never turned off because it never got that warm, but he had one heater set up in the space (not sure how big) so it never turned off, that's why he says to wire to the breaker. Again, I plan to leave the heaters on all the time so I can get the benefits of the radiant heat. I appreciate his thoughts though and hope that I am more satisfied with these in my situation that he was.

#6 wire - DAMN! I was expecting #8. I hadn't really figured that out though. Is #6 required on a 50 amp circuit? I really appreciate your help with this - especially to hear about tapping off for the thermostat, I wondered if that would work.

And I realize now that the purpose of the contactor is to be able to control all 3 with one thermostat - like a relay on a car where you trigger the high amp circuit with a lower amp circuit through a switch - in this case my thermostat. It's making sense now!

 

[Aceman]

#6 wire - DAMN! I was expecting #8. I hadn't really figured that out though. Is #6 required on a 50 amp circuit?

#6 Romex, yes. If you use conduit, #8 Thhn will work.

And I realize now that the purpose of the contactor is to be able to control all 3 with one thermostat - like a relay on a car where you trigger the high amp circuit with a lower amp circuit through a switch - in this case my thermostat. It's making sense now!

Exactly.

 

[tboltkc]

My building is all steel, so I will be using conduit anyway. I'll price it out with #8 THHN vs #6 Romex vs 3 runs of #12 romex. I have to go pretty far, almost 70 feet to the longest run. I am installing this in a 30 X 40 space, and actually have 2 of these "systems" with 2 thermostats, 2 contactors and 6 heaters.

Thanks again, there is such great knowledge on this forum!

 

[Aceman]

My building is all steel, so I will be using conduit anyway. I'll price it out with #8 THHN vs #6 Romex vs 3 runs of #12 romex. I have to go pretty far, almost 70 feet to the longest run. I am installing this in a 30 X 40 space, and actually have 2 of these "systems" with 2 thermostats, 2 contactors and 6 heaters.

I knew I should of asked the building type in the beginning. I mentioned Romex because I assumed wood framed building. Now that I know you're running conduit, don't try to pull Romex into it, you will hate life. Trust me.
Use #12 Thhn instead, if you run #8 Thhn, you will have to carry that #8 clear to the end, to the farthest heater, even though it only draws 12.5 amps. If you run individual #12 circuits, you will drop each circuit off at the heater it supplies. Now you've only got #12's running clear down to the last heater. Individual heater circuits help with troubleshooting and reliability too, if one heater goes down, it only trips it's individual breaker instead of taking the other 2 heaters down with it.

 

[vinculum]

Tboltkc,

You got it right. Properly wiring up these heaters is an investment in both time and money. I recommend evaluating a single heater for performance and placement before making such an investment.

You may find that you want to place 2 of them close together and overlap the coverage. Best to find out now, before all that EMT and copper is run.

It's unacceptable to me when a single heater at the minimum distance to combustibles can't warm a 1/2" ratchet in over 6 hours of on time while gulping 3000 watts. The only thing that really got warm was the top of my head.

Aceman's wiring advice in his last post was correct should you continue your installation.

Good luck!
Dr V

 

[tboltkc]

I have pulled Romex through conduit and you are right - it *****! How many #12 THHN can I run through 3/4" conduit? I don't mind running the wire for 3 circuits (probably actually 4 in case I add another heater - the contactor can handle 4), but I don't want to run 3 (or 4) runs of conduit. That alone makes me wish I'd have built a wood framed building...

 

[Aceman]

I have pulled Romex through conduit and you are right - it *****! How many #12 THHN can I run through 3/4" conduit? I don't mind running the wire for 3 circuits (probably actually 4 in case I add another heater - the contactor can handle 4), but I don't want to run 3 (or 4) runs of conduit. That alone makes me wish I'd have built a wood framed building...

16-#12 THHN in a 3/4" emt.

 

[tboltkc]

Thanks for the help.

 

[tboltkc]

I am finally getting around to this, and have decided to run 2 30A circuits using #10 THHN though EMT - planning ahead for adding a 4th heater in the future.

My question involves the contactor. Since both circuit breakers are connected to the same lugs in the contactor, and the heaters are also connected to the same lugs in the contactor, will it really act like 2 30A circuits to where if one heater has an issue it will actually trip just one of the breakers? There really isn't a way to determine which breaker will be handling which heater(s) is there? Or am I completely missing something on how to hook these up through the contactor panel?

 

[rinny_tin_tin]

I am finally getting around to this, and have decided to run 2 30A circuits using #10 THHN though EMT - planning ahead for adding a 4th heater in the future.

My question involves the contactor. Since both circuit breakers are connected to the same lugs in the contactor, and the heaters are also connected to the same lugs in the contactor, will it really act like 2 30A circuits to where if one heater has an issue it will actually trip just one of the breakers? There really isn't a way to determine which breaker will be handling which heater(s) is there? Or am I completely missing something on how to hook these up through the contactor panel?

Something is wrong here....the Ebay link provides little in the way of info. You state that there are three poles to the contactor - is it a three phase unit? Generally, the way these things work is that all you need to do is run a single ckt to the heater with 4 conductor - two poles for the 240, the neutral for 120 service, and the gnd wire for the metal shroud, etc. The thermostat should be able to "pilot" the contactor - so the contactor rating of 60 A refers to the continuous current rating load side of the contactor. However, just because your contactor is rated 60A does not mean that it is feeding a 60A load. If I were you - look at the user manual that came with it - if one did, and check the manufacturers web site @ http://www.fostoriaindustries.com/

What model no is it anyway? Is it one of these
http://www.tpicorp.com/Catalog/FOSTORIAINFRAREDHEAT/e-SingleElementQuartzTube/spec.pdf

 

[tboltkc]

Thanks for the quick response, and you are right, there is little info on that link. Also little info came with the components. The contactor is a 60A, with a 208/240V switch, and the contactor is 1 or 3 phase, up to 480V I believe. Heaters are CH-57 (3000 watt) and I have 3 right now, contactor should be able to handle up to 4, so I am wiring for the possible addition of a 4th.

The heaters draw 12.5 amps each. One of the earlier recommendations in this thread was to run seperate circuits for each heater. I don't want to do that because of space in my breaker panel, so I want to run 2 circuits that can handle 2 heaters.

But as I was figuring up the list of stuff I need to buy, I became concerned with the way the contactor is wired. The L1 and L2 will be hooked to 2 30A breakers, and the T1 and T2 will be connected to the 2 circuits going to the heaters. It seems like the contactor is really designed just to take in 1 60A circuit, not multiple because they'd all be combined on the way out anyway.

Sorry if my terms aren't right, but hopefully you understand my problem. In short, it seems like I should put 1 50 or 60A breaker in my box, and run it to the contactor, then run my 2 circuits off of that, but then I lose the disconnection of the heaters recommended by a previous poster.

 

[rinny_tin_tin]

Thanks for the quick response, and you are right, there is little info on that link. Also little info came with the components. The contactor is a 60A, with a 208/240V switch, and the contactor is 1 or 3 phase, up to 480V I believe. Heaters are CH-57 (3000 watt) and I have 3 right now, contactor should be able to handle up to 4, so I am wiring for the possible addition of a 4th.

The heaters draw 12.5 amps each. One of the earlier recommendations in this thread was to run seperate circuits for each heater. I don't want to do that because of space in my breaker panel, so I want to run 2 circuits that can handle 2 heaters.

But as I was figuring up the list of stuff I need to buy, I became concerned with the way the contactor is wired. The L1 and L2 will be hooked to 2 30A breakers, and the T1 and T2 will be connected to the 2 circuits going to the heaters. It seems like the contactor is really designed just to take in 1 60A circuit, not multiple because they'd all be combined on the way out anyway.

Sorry if my terms aren't right, but hopefully you understand my problem. In short, it seems like I should put 1 50 or 60A breaker in my box, and run it to the contactor, then run my 2 circuits off of that, but then I lose the disconnection of the heaters recommended by a previous poster.

Ok - When you say you are running two 30A breakers - you mean a single two-pole breaker @30A...gotcha.

So- lets say your single 3 heater load is 3 * 3kW= 9kW
At 240 V that is 9kW/240 37.5A (or 12.5 * 3)
[Lets say 40 A for the heck of it]

OK - so the contactor is rated at 60A, but two (heater systems) x 37.5 A = 75..that is 15 more Amps than the contactor is rated for.

So -- in essence, the 60 A contactor won't do the job you were thinking (if I understand correctly) and yo will need a separate contactor anyway.

So...I would run 4 conductor 10 AWG of THHN (or other 90 degree rated) to each heater (one for the existing one and one to allow for future possible expansion) This should resolve independent switching concerns.

However - when you say you plan to add a 4th you mean just another single 12.5 A element, your current becomes 4 * 12.4 = 50A, well within the rating of the contactor, in which case you would run 8 AWG THHN, etc.

But...I need to ask....where would you put the 4th element? Would you put it in the same shroud with the other three? Is the shoroud listed (rated for this other added element?

 

[tboltkc]

When I'm saying 30A breakers, I mean 2 240V 2 pole 30A breakers. It's all 240V.

And when I say I have 2 systems, I have two completely seperate systems. Each with 3 heaters (which are each self-contained not multiple elements in one appliance), a 60A contactor and a line voltage thermostat. They will not be combined in any way, so for now, forget that I have 2 systems - I will end up with 2 completely seperate systems.

When I say adding a 4th heater, I just mean that I will buy a 4th complete heater that I will wire in when/if the time comes. I plan to run the wire and put the box there. For my current question, it's a moot point.

I'm just wondering about hooking the breaker(s) to the contactor and in turn the contactor to the heaters. I am thinking I cannot (or at best I gain no advantage) hook more than one breaker to the L1 and L2 inputs on the contactor. Hooking 2 breakers to the contactor would just make them into 1 circuit, right? So if one heater overloads, and a breaker pops, won't it just continue to get power from the other breaker until it pops? So it seems like I should just put in 1 big breaker (50 or 60A) and run that to the input side of the contactor and then I could still run the smaller, easier to work with wire out of the load side of the contactor to the heaters. Thermostat is also 208/240V so I plan to just tap into the feed into the contactor to go to the thermostat.

 

[rinny_tin_tin]

I guess the nomenclature is the problem here....

Here goes:

Feed 10 AWG, 4-conductor THHN cable from a two-pole 40A 240V circuit-breaker (these may be two individual ckt breakers however linked together with bar between the toggles, or a "fat" breaker that takes up two spaces and which straddles two poles) to contactor's L1/L2 terminal. T1 & T2 from the contactor feeds your three heaters.

Double check if your thermostat really takes 240 as it typically is frowned upon to run control wiring at 240 - typically its 120 (or 12 VDC) Ground the case of the ltg fixture - there should be a lug somewhere.

You may wind up with a unused neutral of your 10 AWG.

Nuff Said

 

[Mellotron]

Double check if your thermostat really takes 240 as it typically is frowned upon to run control wiring at 240 - typically its 120 (or 12 VDC) Ground the case of the ltg fixture - there should be a lug somewhere.

I found the contactor specs. 120v coil.

 

[rinny_tin_tin]

I found the contactor specs. 120v coil.

Aha.....good work!

 

[VHF]

I'm a little confused about your contactor based on the specs you posted. It appears to be a 3-pole unit, and the model # suggests a 60A overall capacity, but then the specs say 30A max. Is that 30A max per pole? But only a continuous 20A per pole rating? That's the only thing I can figure that would make sense.

If that is the case, then running two heaters (2 * 12.5A = 25A) off each pole would exceed the implied continuous rating for each pole (60A/3 = 20A). Also, running two heaters off a 30A breaker would exceed the 80% rule for continuous loads (electric heat is considered a continuous load.) (If the heaters were only 12.0A each then you would be OK on the 80% rule, but 12.5A each puts you over.)

It seems like the safest approach would be 3 separate 20A breakers as Aceman originally suggested, each feeding one heater through 1 pole of the contactor. However, this would consume 6 slots in your breaker box (3 double breakers) and not provide for a possible 4th heater.

You might consider adding a subpannel to give you room for more breakers.

 

[tboltkc]

I found the contactor specs. 120v coil.

Not the right one. The contactor is GE and it's definitely a 208/240V coil, and so is the thermostat. I don't have the parts in the house anymore to give the numbers, but I am sure they are all 240.

 

[tboltkc]

It seems like the safest approach would be 3 separate 20A breakers as Aceman originally suggested, each feeding one heater through 1 pole of the contactor. However, this would consume 6 slots in your breaker box (3 double breakers) and not provide for a possible 4th heater.

You might consider adding a subpannel to give you room for more breakers.

I thought about the subpanel, but I don't get how I could do the separate breakers. The contactor has 3 feed lugs, L1 - L3 and 3 output lugs T1- T3. It's 240V so I need two lugs for hot, right? Seems like the L3 and T3 are for using the contactor in a 3 phase system, so I don't need them.

 

[Mellotron]

Not the right one. The contactor is GE and it's definitely a 208/240V coil, and so is the thermostat. I don't have the parts in the house anymore to give the numbers, but I am sure they are all 240.

Crud sorry. Here I was trying to help thinking I found the one from the same ebay seller. Clearly he has different flavors of contactors then.

 

[VHF]

The 3-pole contactor was probably intended for 3-phase, however using it to switch 3 separate single-phase 240VAC circuits will work. It does mean you are only switching one of the hot legs, but for a true 240V load (w/o a neutral) that is sufficient to break the circuit. It would be the same as if controlling a single heater directly from a SPST 240VAC line-voltage thermostat... only a single leg is broken to open the circuit.

I'd like to know what they have in mind when they say 4 heaters can be run off this contactor. Sure, the 60A capacity is greater than the 50A that 4 heaters will draw, but just how do they plan to wire it and fuse/breaker it? To spread 4 heaters across 3 poles would pretty much require connecting L1-L2-L3 together essentially turning it into a single pole contactor. If using a single 60A breaker to protect it, you would be violating the 80% NEC rule for continuous loads (with 4 heaters.) Further more, you would have to wire the entire circuit with #6 wire... all the way to the farthest heater.

Seems like almost anything other than a separate 20A circuit for each 12.5A heater runs afoul of the 80% rule (i.e. 2 heaters on 30A, 4 heaters on 60A.) Now 3 heaters on a single 50A breaker would be OK, but you would still have to run #6 Romex (or #8 in conduit) for the entire circuit unless you appropriately fused smaller conductors (#12 @ 20A or #10 @ 30A.)

It's too bad running two heaters on a 30A circuit with #10 wire doesn't quite work out (80% rule again.)

You mentioned that you were going to have two of these systems. You could put a 100A breaker in your main panel to feed a new 100A main lug sub panel which would handle both of your systems (assuming it makes sense to have a single panel location-wise). In the subpanel you would have a 20A 240VAC breaker for each heater. Each of those circuits would go through one pole of the contactor (again limiting you to 3 heaters per contactor.) This would allow you to run #12 wire to each heater. A 12 position sub panel would support 6 heaters total. Unfortunately, no provision for adding an extra heater to either system.

 

[VHF]

Hey, I just had an idea how you support 4 heaters on each system!

You would still need a subpanel as described previously, and it would need to be a 125A subpanel breakered at 125A to support two systems of 4 heaters each. You would still have one 20A breaker for each heater--you would need at least a 16 position panel to support a total of 8 heaters. 3 heaters in each system would go though the contactor--one pole per heater. The 4th heater would be switched directly by the 240VAC line voltage thermostat--as long as it is rated for at least 12.5A it can directly switch one heater, so might as well take advantage of that! It would, of course, also switch power to the the coil on the contactor to control the other 3 heaters. Entire system can be wired with #12 since each heater will be individualy protected by a 20A breaker.

 

[tboltkc]

Thanks for the ideas!