Questions about wiring for compressor and welder

[PT Doc]

I need to run a 230V outlet to my garage for a compressor that I'm getting next week. It's a Quincy 251CP80VCB:

http://www.northerntool.com/shop/tools/product_200451863_200451863

The compressor draws 23A under constant load but draws a lot on start up according to Larry at Quincy.

At some point down the road, I'll end up with a welder like the Hobart Ironman 230:

http://www.northerntool.com/shop/tools/product_47864_47864

The welder draws 32.5A at 230v.

I have a sub-panel in the unfinished basement and will run the line to the shared wall between the basement/garage. The length of wire would be about 30 feet.

I spoke with Hobart today and they stated that I needed to run a 6/2 line. The welder comes with a Nema 6-50 6 foot plug wired at the factory. I stopped by a farm store today and saw this welder and was surprised that the wire used in the 6' plug was 12G.

I spoke with Quincy yesterday and they recommend 10/2 for a short run and 8/2 for a long run to power the outlet where the compressor will be hooked up. I didn't ask what the distance equated to but since I want to eventually have the ability to power both (not at same time), I will run 6 gauge wire.

Now here are the questions:

1-Since this is likely to only things that the 230V circuit will power, would running 6/3 be a waste?

Since the Hobart is a Nema 6-50 male plug, I need a 6-50 female plug. I didn't see this at Home Depot but maybe Lowe's will have this. I need to wire the compressor to this outlet and would rather get a wire w/plug already made. I don't see myself moving this compressor around so it will likely stay about 10-12' from the plug. (Quincy recommended hard wiring this but for my application I'd prefer a wire w/plug).

2-Where to get a plug/wire setup and what gauge? (I'll be running 6/2 likely from the sub-panel to the garage outlet. (Home Depot had 12,10,8 and 6 SOO wire (3 strands) readily available.

Anything that I am missing? Thanks for the help.

 

[ishiboo]

I need to run a 230V outlet to my garage for a compressor that I'm getting next week. It's a Quincy 251CP80VCB:

http://www.northerntool.com/shop/tools/product_200451863_200451863

The compressor draws 23A under constant load but draws a lot on start up according to Larry at Quincy.

At some point down the road, I'll end up with a welder like the Hobart Ironman 230:

http://www.northerntool.com/shop/tools/product_47864_47864

The welder draws 32.5A at 230v.

I have a sub-panel in the unfinished basement and will run the line to the shared wall between the basement/garage. The length of wire would be about 30 feet.

I spoke with Hobart today and they stated that I needed to run a 6/2 line. The welder comes with a Nema 6-50 6 foot plug wired at the factory. I stopped by a farm store today and saw this welder and was surprised that the wire used in the 6' plug was 12G.

I spoke with Quincy yesterday and they recommend 10/2 for a short run and 8/2 for a long run to power the outlet where the compressor will be hooked up. I didn't ask what the distance equated to but since I want to eventually have the ability to power both (not at same time), I will run 6 gauge wire.

Now here are the questions:

1-Since this is likely to only things that the 230V circuit will power, would running 6/3 be a waste?

Since the Hobart is a Nema 6-50 male plug, I need a 6-50 female plug. I didn't see this at Home Depot but maybe Lowe's will have this. I need to wire the compressor to this outlet and would rather get a wire w/plug already made. I don't see myself moving this compressor around so it will likely stay about 10-12' from the plug. (Quincy recommended hard wiring this but for my application I'd prefer a wire w/plug).

2-Where to get a plug/wire setup and what gauge? (I'll be running 6/2 likely from the sub-panel to the garage outlet. (Home Depot had 12,10,8 and 6 SOO wire (3 strands) readily available.

Anything that I am missing? Thanks for the help.

1. I would run 6/3 just in case, but that's how I am. Might want to plug a stove in for powder coating, or a dryer for drying shop rags, etc

2. I would do 6-50, since that's what the Hobart has. I would run #10 for the compressor, cycle times are short and it's a short run. The welder gets by with a #12 because it's such a short cord, if you have an outlet I would run at least #10 if not #8 for an extension cord for the welder.

Personally, I prefer the twist-lock plugs to the straight blades but that's entirely up to you. 50a twist-lock gear gets kinda expensive.

 

[ForceFed70]

Have you considered putting a sub-panel in your garage?

Code does allow you to feed a subpanel from another subpanel.

This way you could run seperate plugs/circuits for your welder and compressor, and it's there in case you ever want to add any circuits in the future.

 

[theoldwizard1]

1. I would run 6/3 just in case, but that's how I am. Might want to plug a stove in for powder coating, or a dryer for drying shop rags, etc

I concur. Actually I would keep a couple extra feet of wire on the other side of the wall so you can pull it through and put a sub panel on it if you want to in the future.

2. I would do 6-50, since that's what the Hobart has. I would run #10 for the compressor, cycle times are short and it's a short run. The welder gets by with a #12 because it's such a short cord, if you have an outlet I would run at least #10 if not #8 for an extension cord for the welder.

If the cord provided is short (<10') I would just replace it with a #10 cord (up to about 20') or perhaps even #8 (up to about 40').

Personally, I prefer the twist-lock plugs to the straight blades but that's entirely up to you. 50a twist-lock gear gets kinda expensive.

Yep.

Any way you go, Google is your friend. Big box store don't stock much in high current receptacles or plus. Electrical warehouses do, but they are expensive. Google is your friend.

 

[PT Doc]

Have you considered putting a sub-panel in your garage?

Code does allow you to feed a subpanel from another subpanel.

This way you could run seperate plugs/circuits for your welder and compressor, and it's there in case you ever want to add any circuits in the future.

Don't really have much need for more wiring than the current 230 dilemma. What gauge wiring would I run from the current sub panel to the proposed sub in the garage? Thanks

 

[930dreamer]

I bought 80 feet of 6/1 ga. off CL for $40. You might find a deal on a returned piece or CL.

 

[ForceFed70]

Don't really have much need for more wiring than the current 230 dilemma. What gauge wiring would I run from the current sub panel to the proposed sub in the garage? Thanks

Whatever guage you want. Just depends on the size of the subpanel you want to use. You could use 6/3 for a 50A (possibly 60?) panel.

 

[PT Doc]

Whatever guage you want. Just depends on the size of the subpanel you want to use. You could use 6/3 for a 50A (possibly 60?) panel.

I must not understand this well. I am planning on running a 6/2 or 6/3 wire from a 50 amp fuse to this proposed outlet. What would I gain by ruining same wire size to a sub panel?

Thanks for all the suggestions guys.

 

[Aceman]

1-Since this is likely to only things that the 230V circuit will power, would running 6/3 be a waste?

Since the Hobart is a Nema 6-50 male plug, I need a 6-50 female plug. I didn't see this at Home Depot but maybe Lowe's will have this. I need to wire the compressor to this outlet and would rather get a wire w/plug already made. I don't see myself moving this compressor around so it will likely stay about 10-12' from the plug. (Quincy recommended hard wiring this but for my application I'd prefer a wire w/plug).

2-Where to get a plug/wire setup and what gauge? (I'll be running 6/2 likely from the sub-panel to the garage outlet. (Home Depot had 12,10,8 and 6 SOO wire (3 strands) readily available.

Anything that I am missing? Thanks for the help.

8-2 NM for the compressor. #8 for the cord as well.

A minimum of 10-2 NM for this welder. #10 for the cord. If you think you may go bigger on the welder in the future, then use #8 or even #6 if you want to spend the money. But #10 will get you by for what you're doing right now.

After I post this, you'll probably see several more people who aren't electricians tell you why it's so wrong to run #10 to a 50 amp welder recep. Then they'll tell you that you should run 6-3 to everything in case you want to plug in a dryer, oven, RV, band equipment for a rock concert, who-knows-what and that it's better to be safe than sorry. I gave you what the code requires, anything more than that is up to you.

Don't forget to pull a permit, also check the cord ends to make sure they'll fit the wire size you're using.

 

[PT Doc]

8-2 NM for the compressor. #8 for the cord as well.

A minimum of 10-2 NM for this welder. #10 for the cord. If you think you may go bigger on the welder in the future, then use #8 or even #6 if you want to spend the money. But #10 will get you by for what you're doing right now.

After I post this, you'll probably see several more people who aren't electricians tell you why it's so wrong to run #10 to a 50 amp welder recep. Then they'll tell you that you should run 6-3 to everything in case you want to plug in a dryer, oven, RV, band equipment for a rock concert, who-knows-what and that it's better to be safe than sorry. I gave you what the code requires, anything more than that is up to you.

Don't forget to pull a permit, also check the cord ends to make sure they'll fit the wire size you're using.

Thank you very much for the specifics and clarity. If I ran 6/3 from the sub panel to just the outlet for now, would this be able to power a smaller sub panel in the future? I would not be using 1 wire (neutral) for now in the nema 6 50 setup but would have it got a future electrical change.

Thanks again.

 

[Aceman]

Thank you very much for the specifics and clarity. If I ran 6/3 from the sub panel to just the outlet for now, would this be able to power a smaller sub panel in the future? I would not be using 1 wire (neutral) for now in the nema 6 50 setup but would have it got a future electrical change.

Thanks again.

Yes, that wire would give you a 55 amp subpanel.

But, at the same time why don't you price out #2 Aluminum SER cable as well. That would give you a subpanel capable of 75 amps and I bet the price of that higher ampacity cable would surprise you.

 

[TWX]

When I had installed my wiring on the outside carport at the old house, I just went with 6ga wire in conduit, with a 10ga ground, and a NEMA 6-50 plug. My compressor has that plug even though it probably draws less than 20 amps at 240V, and I figured if I ever got into welding I'd need the amperage.

When I added a new plug to the new place I did the same thing, NEMA 6-50 with 6ga wire.

Only consideration, if I had thought to do it at the old place, I should have run a neutral in addition to hot, hot and ground, in case I ever got something that required a 14-50 connector.

At my new place, the new receptacle is only a couple of feet from the subpanel, so I didn't bother to add the neutral, and I managed to use what I had left over for wiring from doing the old one. If I ever added a remote panel I would go with the four-wire configuration.

 

[ForceFed70]

I must not understand this well. I am planning on running a 6/2 or 6/3 wire from a 50 amp fuse to this proposed outlet. What would I gain by ruining same wire size to a sub panel?

Thanks for all the suggestions guys.

The subpanel will allow you to hook up additional circuits in the future. Plus you can then run seperate circuits for the compressor and welder (would still trip if you run both at the same time tho).

I would step up to a 4ga conductor to allow you an 80Amp(ish) subpanel. Where at that point you could likely run the compressor and welder at the same time.

I always seem to be adding circuits for something and having a subpanel right in the garage makes it a lot easier.

 

[eriksalo]

I will try and answer both from a NEC perspective and from a practical perspective.

1) Should you run 6/2 or 6/3? I can see no reason whatever to run 6/3 wire in this application. The reason you would consider running 6/3 wire is if your device had a need for BOTH 120V and 240V power at the device. This happens all the time in hot tubs and air conditioners. In a hot tub for example, the pump and heater run on 240 and the stereo and lights run on 120. Remember that 6/2 has three conductors, two are insulated (both hot) and one is a bare ground while 6/3 has four conductors, three are insulated (two hot, one neutral) and one is bare ground. For that hot tub, the 240 bits hook to the two hot wires and the 120 bits hook from one hot to the neutral. By code, the neutral must be the same gage as the hot wires. I think 6/2 would be fine for your needs.

The exception to this is if you decided you wanted to run a sub-panel (btw, I think this is a good idea, seems I always need more power in my shop). In that case, you would be required to run 6/3 so you would have a neutral return for any 120V devices you power from that sub panel.

If you don't like the sub-panel idea, then I would at a minimum recommend buying one of those single breaker 50Amp disconnects and mounting it near your compressor/welder outlet. (these are called "manual disconects" and many refer to them as "spa disconnects"). It looks just like a sub-panel but just has one breaker (some are just switches and some have GFCI but I recommend the breaker variety in this case). These are required for A/C and hot tubs. While not strictly required by code for you, they are cheap (you can get them at HD or Lowe's) and a good idea for both safely and convenience. You have a built in switch and an extra measure of safety.

2) What about the plug? This is a tough question. I have half a dozen 30a 240V outlets in my shop all on 30A twist lock plugs. Just like Ishiboo said, I think the twist locks are much better. For the NEMA plugs, they're kind of hard to pull out and there's a real chance of touching the two hot conductors while trying to get a grip. The twists feel safer, stay in much more securely and I just like them better. However, the twist locks aren't commonly available in amperage's larger than 30A. This would be OK for your compressor but not for the welder.

I have a 50A welder outlet and for that, I (reluctantly) use a NEMA 6-50. All my really big stuff is hard wired (on local manual disconnect boxes, they are very much worth the few dollars they cost). You should have no trouble finding female NEMA 6-50 outlets but they will all be for electrical boxes. If it were me, I would wire your 6/2 into a manual disconnect and then wire that to a small 4x4 steel electrical box where your NEMA 6-50 female receptacle is located.

3) What about the plug wires? For the plug wires (e.g. the wires that go from the device to the plug on the wall) I really like the rubber encased cord. It's tough and I've had good luck with it. The only negative is it isn't cut resistant. For that, THHN in flexible conduit is best. Strictly speaking, you need 10 gage for your compressor and 8 gage for your welder.

4) What about running 10 gage for the welder? One poster said you could probably run 10 gage for the welder. Fact is, he's right in the practical sense. 10 gage wire is rated up to 30 Amps. Since the welder only takes 32.5 Amps max, that's the draw only when you have it running full bore, which will be somewhere between never and almost never. That's a darn big welder and unless you're in the ship building business, you will not often have the need to run it on max.

By code, you need an 8 gage wire on that welder. However, if you put a 30 Amp fuse in your local disconnect box, 10 gage is OK (this might not be code but it would be safe). I do this on my very big welder. I have one of those old 300Amp Lincoln Idealarc's. It's plate says it needs a 105A circuit. Since I only have 100A service, I technically can't run it. However, what I did was put 6/2 gage wire on a 50A breaker (both in my main box and on my local disconnect). If the welder ever pulls more than 50A, it would pop the breaker and thus the 6 gage wire will never be asked to carry more current than it's safe rating.

 

[PT Doc]

I will try and answer both from a NEC perspective and from a practical perspective.

1) Should you run 6/2 or 6/3? I can see no reason whatever to run 6/3 wire in this application. The reason you would consider running 6/3 wire is if your device had a need for BOTH 120V and 240V power at the device. This happens all the time in hot tubs and air conditioners. In a hot tub for example, the pump and heater run on 240 and the stereo and lights run on 120. Remember that 6/2 has three conductors, two are insulated (both hot) and one is a bare ground while 6/3 has four conductors, three are insulated (two hot, one neutral) and one is bare ground. For that hot tub, the 240 bits hook to the two hot wires and the 120 bits hook from one hot to the neutral. By code, the neutral must be the same gage as the hot wires. I think 6/2 would be fine for your needs.

The exception to this is if you decided you wanted to run a sub-panel (btw, I think this is a good idea, seems I always need more power in my shop). In that case, you would be required to run 6/3 so you would have a neutral return for any 120V devices you power from that sub panel.

If you don't like the sub-panel idea, then I would at a minimum recommend buying one of those single breaker 50Amp disconnects and mounting it near your compressor/welder outlet. (these are called "manual disconects" and many refer to them as "spa disconnects"). It looks just like a sub-panel but just has one breaker (some are just switches and some have GFCI but I recommend the breaker variety in this case). These are required for A/C and hot tubs. While not strictly required by code for you, they are cheap (you can get them at HD or Lowe's) and a good idea for both safely and convenience. You have a built in switch and an extra measure of safety.

2) What about the plug? This is a tough question. I have half a dozen 30a 240V outlets in my shop all on 30A twist lock plugs. Just like Ishiboo said, I think the twist locks are much better. For the NEMA plugs, they're kind of hard to pull out and there's a real chance of touching the two hot conductors while trying to get a grip. The twists feel safer, stay in much more securely and I just like them better. However, the twist locks aren't commonly available in amperage's larger than 30A. This would be OK for your compressor but not for the welder.

I have a 50A welder outlet and for that, I (reluctantly) use a NEMA 6-50. All my really big stuff is hard wired (on local manual disconnect boxes, they are very much worth the few dollars they cost). You should have no trouble finding female NEMA 6-50 outlets but they will all be for electrical boxes. If it were me, I would wire your 6/2 into a manual disconnect and then wire that to a small 4x4 steel electrical box where your NEMA 6-50 female receptacle is located.

3) What about the plug wires? For the plug wires (e.g. the wires that go from the device to the plug on the wall) I really like the rubber encased cord. It's tough and I've had good luck with it. The only negative is it isn't cut resistant. For that, THHN in flexible conduit is best. Strictly speaking, you need 10 gage for your compressor and 8 gage for your welder.

4) What about running 10 gage for the welder? One poster said you could probably run 10 gage for the welder. Fact is, he's right in the practical sense. 10 gage wire is rated up to 30 Amps. Since the welder only takes 32.5 Amps max, that's the draw only when you have it running full bore, which will be somewhere between never and almost never. That's a darn big welder and unless you're in the ship building business, you will not often have the need to run it on max.

By code, you need an 8 gage wire on that welder. However, if you put a 30 Amp fuse in your local disconnect box, 10 gage is OK (this might not be code but it would be safe). I do this on my very big welder. I have one of those old 300Amp Lincoln Idealarc's. It's plate says it needs a 105A circuit. Since I only have 100A service, I technically can't run it. However, what I did was put 6/2 gage wire on a 50A breaker (both in my main box and on my local disconnect). If the welder ever pulls more than 50A, it would pop the breaker and thus the 6 gage wire will never be asked to carry more current than it's safe rating.

Thank you very much for the information. I appreciate the detail since this shows the reasoning.

 

[Aceman]

4) What about running 10 gage for the welder? One poster said you could probably run 10 gage for the welder. Fact is, he's right in the practical sense. 10 gage wire is rated up to 30 Amps. Since the welder only takes 32.5 Amps max, that's the draw only when you have it running full bore, which will be somewhere between never and almost never. That's a darn big welder and unless you're in the ship building business, you will not often have the need to run it on max.

By code, you need an 8 gage wire on that welder. However, if you put a 30 Amp fuse in your local disconnect box, 10 gage is OK (this might not be code but it would be safe).

Since you're making references to code, please show me which code article requires #8 to that welder, I'd also like to know which one requires me to put that #10 on a 30 amp breaker(rather than a 50) for that welder as well.

 

[eriksalo]

Since you're making references to code, please show me which code article requires #8 to that welder, I'd also like to know which one requires me to put that #10 on a 30 amp breaker(rather than a 50) for that welder as well.

You ask a fine question and it's one I've looked into quite a bit. Since you asked a specific question, I'll give you a specific answer and I'll stick to my original answer since I have been down this road more than once. The NEC is a large document and there are many interesting exceptions for things like welders and motors. I have found there's a distinction between what the NEC book says exactly and what inspectors will pass. However, in this case I think the answer is clear by strict NEC interpretation and I'll try to make the case based on what the NEC says.

I've been assuming for the sake of this discussion that we're talking about NM-B (Romex) wire. If he is use running THHN in conduit then the numbers go up a bit.

The NEC is complex document but you asked so I will do my best to answer......

When determining conductor sizing and overcurrent protection, the NEC requires you take six factors into account:

1) Continuous Loads
2) Terminal temperature ratings
3) Conductor Insulation
4) Conductor Ampacity
5) Special Application
6) System Voltage
​

As a general process, three steps are required to find conductor size and overcurrent protection capacity of a branch circuit.

Step 1: Size the overcurrent device: Sections 210.20(a), 215.3 and 384.16(d)

A summary of this is the overcurrent protection device must be sized no less than 100% of the noncontinuous load plus 125% of the continuous load​

Step 2: Select the conductor to comply with correct ampacity (Sections 110.14(c), 210.19(a), 215.2 and 230.42(a)

Sections 210.19(a), 215.2 and 230.42(a) require the conductor to be sized no less than 100% of the noncontinuous load, plus 125% of the continuous load.
There are lots in interesting bits in 110.14(c) about temperature rating to take into account but the bottom line is that since 1996 you can use the 75C column in table 310.16 for loads under 100Amps​

Step 3: The conductor must also be protected against overcurrent in accordance with section 240.3

Let's start with what the NEC specifies for "general wiring." This is table 310.16. I contend the application in question MUST be considered as general wiring but more on that later. Note that there are seven columns in this table for different ambient conditions and wire types. In this table, it shows between 30 and 40A for 10 gage wire. However, for the small wires (14, 12 and 10 gate) there's an asterisk. Here's what it says: "* Small Condutors. Unless specifically permitted in 240.4(E) through (G), the overcurrent protection shall not exceed 15 amperes for 14 AWG, 20 amperes for 12 AWG, and 30 amperes for 10 AWG copper"​

There are also some headache inducing provisions in 301.15.B.6 that de-rate available ampacities but I don't think they apply to this case.

So at the "general wiring" level, I think it's clear you can only run 30A breaker for that 10 gage wire and that 10 gage wire can only be asked to carry up to 30A spike (noncontinuous) current. Also, since the max continuous amperage is 32.5A, that violates the "general wiring" capacity of NM wire as defined in 310.16 and you will need 8 gage. There is a "next size up" provision for overcurrent in 240.3 that you might argue but the inspectors never buy it and they are right since that provision only applies to the overcurrent protection device and not the conductor itself. A bigger breaker is sometimes useful for motor wiring but is not useful for welders or general wiring.


Now, let me make the case the other way. There are exceptions in the NEC for both welders (based on duty cycle) and for motors (based on start up current). The one I want to talk about is NEC 630.11 with the actual exception for welders being listed in 240.4. This provision essentially allow for "undersizing" wire for a dedicated welding application based on duty cycle. 630.11 also gets you out of the asterisk provision I talked about above in 310.16 since that provision does not apply to welder circuits (or motor, some A/C, and some other misc exceptions). I would have to do the math but I think you could actually get away with 12 gage wire for this welder if it were a dedicated circuit. If you do try this trick, you need to label the wiring conspicuously that it's "For Welder Use Only" AND it has to be hard wired into the box (plug not allowed).

The above is true for the conductor. I don't think you can make the case for a welder that a 50A breaker is OK for 10 gage wire. There is an exception for motors where you can use a bigger breaker (although never bigger than 125% of the continuous load as stated in 210.20(a), 215.3 and 384.16(d) ), to allow for the inrush current at starting but that's a whole different discussion.

Problem is, you aren't making a circuit JUST for a welder or JUST for a compressor. The question here was "I want a circuit for a welder OR a compressor." Also, he wanted to have a plug in system. If you put a plug in the system the inspector will argue correctly that's it's "general wiring" since it doesn't take a licensed electrician to plug in something different. Also, it's a valid argument that it's "general wiring" since there will be two different uses. You can not say, "well, when the welder is plugged in, the circuit is correctly undersized for a welder duty cycle and when the compressor is plugged in is it's correctly sized for that. The NEC states that these exceptions only apply to dedicated circuits.

I hope I answered your question. There is sometimes a difference between what's code and what's actually safe. There often a difference between (what I think) is code and what the inspector thinks is code! However, for residential and shop wiring, the difference is cost to use the next bigger gage wire isn't terrible. You will usually be safe if you stick with (14 Gage / 15 Amp, 12 Gage / 20 Amp, 10 Gage / 30 Amp, 8 Gage / 40 Amp, 6 Gage / 50 Amp.). The whole point of all this sizing is to keep you from pulling so much current through a conductor that it heats up and starts a fire, that's a good goal.

Erik

 

[Aceman]

I think you use a lot of words and like to beat around the bush...

Give me the no-******** short version of which articles say I can't do what I mentioned above. I don't care about inspector interpretation, I want the NEC articles you're telling me won't allow it.

 

[theoldwizard1]

But, at the same time why don't you price out #2 Aluminum SER cable as well.

A bit off the original topic.

Would the Aluminum SER wire actually fit into a 50 or 75A breaker ? Would there be any issue about Aluminum wire directly connected to the breaker or is a special breaker required ?

 

[eriksalo]

I think you use a lot of words and like to beat around the bush...

Give me the no-******** short version of which articles say I can't do what I mentioned above. I don't care about inspector interpretation, I want the NEC articles you're telling me won't allow it.

Hi Aceman; If you want to use the NEC as your guide, a lot of words are required! I'm not going for BS, just a complete answer based on a really complicated set of rules that have lots of exceptions and provisions.

However, I can answer your question with two sentences:

Table 310.16 at the bottom says, "* Small Conductors. Unless specifically permitted in 240.4(E) through (G), the overcurrent protection shall not exceed ..... 30 amperes for 10 AWG copper" There is nothing in 240.4 that permits an exception in this specific application and the stated load of the device is greater that 30 amperes so a 10 gage circuit is not sufficient.

How's that?

 

[pattenp]

I've put 60A breakers on #2 AL so I know those will fit, not sure about a 50A. Just make sure the breaker is rated for CU/AL, I believe most are. Also it's good to use the anti-oxidation paste on AL connections.

A bit off the original topic.

Would the Aluminum SER wire actually fit into a 50 or 75A breaker ? Would there be any issue about Aluminum wire directly connected to the breaker or is a special breaker required ?

 

[MrMark]

Hi Aceman; If you want to use the NEC as your guide, a lot of words are required! I'm not going for BS, just a complete answer based on a really complicated set of rules that have lots of exceptions and provisions.

However, I can answer your question with two sentences:

Table 310.16 at the bottom says, "* Small Conductors. Unless specifically permitted in 240.4(E) through (G), the overcurrent protection shall not exceed ..... 30 amperes for 10 AWG copper" There is nothing in 240.4 that permits an exception in this specific application and the stated load of the device is greater that 30 amperes so a 10 gage circuit is not sufficient.

How's that?

Seems right to me. Your argument that the facts here require a general purpose circuit seems unimpeachable. Seems electrician school has ended.

 

[Aceman]

Hi Aceman; If you want to use the NEC as your guide, a lot of words are required! I'm not going for BS, just a complete answer based on a really complicated set of rules that have lots of exceptions and provisions.

However, I can answer your question with two sentences:

Table 310.16 at the bottom says, "* Small Conductors. Unless specifically permitted in 240.4(E) through (G), the overcurrent protection shall not exceed ..... 30 amperes for 10 AWG copper" There is nothing in 240.4 that permits an exception in this specific application and the stated load of the device is greater that 30 amperes so a 10 gage circuit is not sufficient.

How's that?

Better!

But, Table 240.4(G) does list electric welder circuit conductors as one exception...?

Have you read 630.12(A) and (B)?

 

[eriksalo]

Sigh, that's why I never start with the short answer. Any discussion about the NEC inevitably leads to an in depth discussion about which exceptions apply to what case.

I maintain it's my considered opinion that 240.4 does not apply to this case.

I tried to say why I think that is true in my long note but let me add just a bit more color to 240.4(g) specifically. Table 240.4(g) of the 2008 NEC applies specifically to Overcurrent protection for specific applications and for "electric welder circuit conductors it references 630.12 and 630.32 which give the specifics.

This is not an "electric welder circuit." It's a general purpose circuit. This is because the user wants to use a welder or a compressor and it's on a plug so there's nothing stopping someone (who isn't an electrician) from plugging in something else. For these reasons, the circuit is not qualified as an "electric welder circuit" and you must revert to the general wiring standard. There are some conventions for making a dedicated circuit (see my other note) but this is not a dedicated circuit and 240.4 does not apply in my opinion.

 

[Aceman]

Sigh, that's why I never start with the short answer. Any discussion about the NEC inevitably leads to an in depth discussion about which exceptions apply to what case.

I maintain it's my considered opinion that 240.4 does not apply to this case.

I tried to say why I think that is true in my long note but let me add just a bit more color to 240.4(g) specifically. Table 240.4(g) of the 2008 NEC applies specifically to Overcurrent protection for specific applications and for "electric welder circuit conductors it references 630.12 and 630.32 which give the specifics.

This is not an "electric welder circuit." It's a general purpose circuit. This is because the user wants to use a welder or a compressor and it's on a plug so there's nothing stopping someone (who isn't an electrician) from plugging in something else. For these reasons, the circuit is not qualified as an "electric welder circuit" and you must revert to the general wiring standard. There are some conventions for making a dedicated circuit (see my other note) but this is not a dedicated circuit and 240.4 does not apply in my opinion.

The bottom line is, you don't have a definitive article prohibiting it. You only have your opinion and I can certainly understand where you're coming from. But, the rules for wiring a welder do not hinge on whether the welder is hardwired or not. It even mentions using a welder recep in 210.21(B)1 Exc 2.

 

[sberry]

Can even use a 12 wire for some machines with 50A,,, single circuit in pipe. A good common sense rule for this crowd is use a wire a size larger than the cord that comes on the unit.