Jumper wire gauge choice

[turbo6justin]

I am looking to make a few slight changes to my garage wiring. As it is now I have 220v run going to 3 different outlets, wired in series for the buzz box welder. So there is a 10g wire running to the back of each outlet and then another 10 gauge out of the outlet to the next box down the line. Because of the outlet design they are both contained under the same screw on the back of the outlet. This circuit works just fine. I also have a 110v mig circuit that likes to trip the 20A breakers. I would like to take one leg of the 220 volt line and split that into a 110v high amp outlet with ground and neutral of course. First can I do this? I don't see a reason why not.

Next question, The 220 line is 10g. The way I am planning to do this I would have the 220 into the box 220 out and a jumper line to each of the 220 and 110 outlet. All 4 wired contained by an appropriate wire nut. Because of the extremely short distance of a few inches at most can I use 12g for the jumper wire to both? 12g is so much easier to work with plus I have it sitting on the shelf.

Hopefully this makes sense, please try not to tear me a new one on this.

So what are the suggestions?

 

[larry_g]

I sitting here saying stay out of this one, but being stupid I will get in just enough to say that the wire size you use is determined by the breaker that is feeding it. If your 220v is more that 20A then 12g is unadvisable. You will also have to go back to the panel to get a neutral so why not pull a hot with it?

Just another question, will your little welder run on 220v? Some of the small ones will or can be converted to 220v.

I am not a licienced electrician but I would not do what your proposing to do.

lg
no neat sig line

 

[turbo6justin]

No on the welder change, and I wouldn't if I could, the portability of a 110 welder can come in handy.

As for pulling another cable I already have an extra lead in the 10g that is unused right now so I have the neutral there already.

I like the explanation that the breaker protects the wire and that the wire needs to support the amerage of the breaker. I was just wondering with the short length how that changes things.

Keep the opinions coming.

 

[ajaynejr]

When too many amperes are passed through a wire, the wire overheats. Overheating is in terms of calories per inch, not calories for the entire length of wire. For a given kind of wire, a short length will overheat its insulation for a given number of amperes the same amount as a long length.

It is okay to use 12 gauge wire when the breaker will be no more than 20 amps. Still it is not advisable to mix wire gauges because someone examining the circuit's calbe as it enters the panel may attach the 10 gauge wire to a larger, 30 amp, breaker.

Don't forget that, (even using all 10 gauge wire) you may not use any 15 or 20 amp receptacles in a circuit breakered at more than 20 amps.

 

[turbo6justin]

It sounds like I need to or at the very least should stick to the same wire gauge.

Is it okay to steal one side of the 220 to use in the 110 outlet, provided a proper ground and neutral are present?

 

[Charles (in GA)]

In your wire size question, you run afoul of NEC 210.19(A)(2) which says that "conductors of branch circuits supplying more than one receptacle for cord and plug connected portable loads shall have an ampacity of not less than the rating of the branch circuit"

You do not say what the amp capacity of the breaker on the 240v circuit is, but table 210.21(B)(3) says you must use a 30 amp receptacle on a 30 amp branch circuit, so you won't be able to use a 15 or 20 amp rated 120v receptacle on one side of the existing 240v hots if that circuit is fed by a 30 amp breaker.

Charles

 

[ishiboo]

I am looking to make a few slight changes to my garage wiring. As it is now I have 220v run going to 3 different outlets, wired in series for the buzz box welder. So there is a 10g wire running to the back of each outlet and then another 10 gauge out of the outlet to the next box down the line. Because of the outlet design they are both contained under the same screw on the back of the outlet. This circuit works just fine. I also have a 110v mig circuit that likes to trip the 20A breakers. I would like to take one leg of the 220 volt line and split that into a 110v high amp outlet with ground and neutral of course. First can I do this? I don't see a reason why not.

Next question, The 220 line is 10g. The way I am planning to do this I would have the 220 into the box 220 out and a jumper line to each of the 220 and 110 outlet. All 4 wired contained by an appropriate wire nut. Because of the extremely short distance of a few inches at most can I use 12g for the jumper wire to both? 12g is so much easier to work with plus I have it sitting on the shelf.

Hopefully this makes sense, please try not to tear me a new one on this.

So what are the suggestions?

I'd change the outlets to 4-wire outlets, and use pigtails to connect the appropriate device. The 120 pigtail would use hot/neutral, and the 240 would use both hots.

 

[turbo6justin]

I understand everything that has been said and it makes sense so far. I do have another question though. The 220 is on a 40 amp double breaker/paired breaker/linked breaker, whatever the correct name is. How exactly does one of these work? Is each side responsible for 1/2 the total amperage? That is how I always envisioned it working, along those lines when one side tripped for whatever reason it would physically take the other side with it to cut off both hots? In that case wouldn't a single hot only be capable of 1/2 the total amps?

I love learning.

 

[Charles (in GA)]

The 220 is on a 40 amp double breaker/paired breaker/linked breaker, whatever the correct name is. How exactly does one of these work?

Its a double pole breaker. The connected handles are connected by a handle tie.

The breaker is 40 amps..................... (40 amps is too much for a 10 gauge wire)

Imagine if you had a 120v circuit where you had a breaker for the hot coming out, and a breaker on the neutral wire going back. This is the same thing. The second breaker is due to the fact that you are using two "hots". The only real difference is that on 120v you have a hot and a grounded conductor (also hot) but because its grounded and for a couple of other reasons I cannot think of right now, it doesn't need a breaker. The 240v circuit uses a hot going out, and a hot coming back, neither grounded, so they both have to be protected.

Probably ought to go to Wilkipedia and do some reading, it will explain it better.

Charles

 

[Gooch]

Its a double pole breaker. The connected handles are connected by a handle tie.

The breaker is 40 amps..................... (40 amps is too much for a 10 gauge wire)

Imagine if you had a 120v circuit where you had a breaker for the hot coming out, and a breaker on the neutral wire going back. This is the same thing. The second breaker is due to the fact that you are using two "hots". The only real difference is that on 120v you have a hot and a grounded conductor (also hot) but because its grounded and for a couple of other reasons I cannot think of right now, it doesn't need a breaker. The 240v circuit uses a hot going out, and a hot coming back, neither grounded, so they both have to be protected.

Probably ought to go to Wilkipedia and do some reading, it will explain it better.

Charles

the Neutral doesn't need a breaker(it's actually illegal to switch the neutral by itself) because it's not possible to have more current flowing on it than what is going out of the hot. there are other dangerous situations that can occur but none of which cause a large increase in current flow. In a 240v circuit the current travels 'out' one hot, and back 'in' the other hot. both have a voltage to ground so faults can cause a large increase in current flow.

a 2 pole breaker will allow it's rated amperage to flow in each 'hot' connected to it. but if one leg pulls more it will open both lines.

 

[mrb]

if the circuit is already installed, where is the neutral going to come from?

 

[bjcouche]

Turbo6justin, I think you've learned a lot by this discussion but I believe there is no simple, inexpensive, code compliant, safe way to accomplish what you want. I am assuming that your 10awg "wire" is 3 conductor plus ground romex. You've stated that it is on a 40A breaker. _Normally_ that in itself is a code violation because 10awg "romex" is only rated for 30A. The way that you get around that is because the NEC allows an _exception_ specifically for welders based on the duty cycle rating of the welder. Technically the "welder outlets" should be labeled as "for welder use only". That way somebody doesn't plug a 40A air compressor into your welder outlet and melt your 10awg wire without tripping the 40A breaker.
I don't like the 2 wires under 1 screw of your current setup either. There are very few devices, especially outlets that are designed for this. What you should have is a hot wire in, hot wire out, and a short wire connecting the outlet, and all 3 wires nutted together. Same goes for the neutral and grounds.
If your wire was 8awg (to support the 40A breaker) or the breaker was 30A then you could place a small subpanel (the 1 or 2 slot kind) at the 240V outlet and feed it with the same size wire as the 240V outlet. The breaker in the box could be 15 or 20A 120V to feed your new 120V outlets. The only problem with this is that you can't do this with a feed that is designed for welder use only.
To me the cheapest and easiest thing to do is run a new 20A 120V 12awg circuit from your main panel.

Brian

 

[turbo6justin]

First of all yes, I have learned a lot so far. You are correct on the wire choice 3 wire plus ground. I agree on the third point, even though there is enough room under the screws for two wires and they are held very securely I will change it over to the short pigtail change setup instead. I like that idea better anyway. I do however have more or should I say contintuing questions.

I have seen mentioned here where people have set up their welding carts to take 220 power from the wall into the cart and then have it split for 220 to the welder/plasma/whatever and 120 available for grinders/drills/etc. Without going through old threads that I read months or years ago I don't remember seeing where too many added a sub box on the cart as you suggest would be a way to have high amps available but also have a 20 amp receptacle that is protected by a 20 amp breaker. I am just brainstorming here but is there a way to put a breaker in a receptacle box?

I already have 12g wire run to the rest of the outlets in the garage, all but 1 circuit is limited to 15 amp at the breaker the other is 20 amp. The chop saw and the welder can and will trip the 20amp breaker so I was looking to keep them on a circuit with 10g wire to see if that helped.

 

[Motofixxer]

If your tripping breakers, with loads seemingly under the rating of the breaker which a chop saw etc should be. Try changing the breaker, they can and do wear out, or just not work properly. It's a cheap option.

 

[slimpickins]

bjcouche hit the bulls eye here. Sounds like he's an electrician! The only thing I might add is that you need to watch your "box fill". The code (in my area at least) has a table that specifies exactly how many wires (excluding ground) and how many wire nuts are allowed to be in an electrical outlet box of a certain cubic inch capacity.

If you're having difficulty working with the 10 gauge wires, its an indication that your outlet box is too small.

Also, the code in Canada doesn't allow for the higher amp breaker/smaller wire for a welder. Check your local code as this may be different for you as well.

Using pigtails is always a good idea, and is code required for ground wires in my area. This is so you can service/change one outlet without disconnecting the ground to downstream outlets.

 

[turbo6justin]

Good afternoon, I'll address a few concerns here. I do not have too many wires in the three boxes in question. It is a 3 gang box with just the 10g in and out and a 12g in and out. As far as boxes go there is actually quite a lot of room in there. I just didn't want to have to deal with more 10g if I didn't have to but I can. It just isn't very cooperative.

The breakers are new. The chop saw is rated at 15 amp and I know this one tends to run a little on the high side. It is a Rigid chop saw quite powerful but it does draw a lot. The welder calls for 15 amps as well, under heavy load it can trip the 20amp breaker. To add misery I need a new table saw and they all run 15 amps as well. I am not surprised they can all trip a 15 amp breaker but the 20 on 12g wire should be exactly what they like.