If I read you properly, you want to leverage a 10/3 to have both 120 & 240 in same line. As long as not using both at same time would work. Depending on municipality, that would be frowned upon as they want singles.

I have a 10/3 for my TS as it needs 120 & 240, and I wanted a 20A outlet for my hand tools that draw a lot. Unfortunately my basement shop (prebuilt) only has 15A outlets. Your problem is going to be you won't be able to find 30A outlet for 120. At least I could not.

I'm assuming you comfortable wiring your panel. Be careful you can get you killed if not.

It comes down to load. Do the math, should work.

 

I used the configuration in your diagram for essentially the same machines without a problem. But I'd consider using the two pole breaker slot to add a sub-panel so you're not limited for future expansion and you can kill the power to all your machines if you have kids around. Depending on the sub-panel, you may also need to purchase a bus bar because it shouldn't be bonded.

 

Will it work. Yes.

Is it proper. No.

Strictly for general purpose recepts. Yes.

For a 250v load and general purpose recepts. No.

 

Your problem is going to be you won t be able to find 30A outlet for 120. At least I could not.
- bonesbr549

I wont need a 30a outlet for the 120, if you look closely, the receptacle in the picture is 240v on the upper and 120v on the lower.

I am probably going to use a 20A breaker instead of a 30A but I will run 10/3 conductor to the shop wall and build a 10/3 "extension cord" for the table saw station that will plug into the wall with a twist lock plug

yes sir, I'm comfortably cautious around electricity, residential loads, anyway.

Strictly for general purpose recepts. Yes.
For a 250v load and general purpose recepts. No.
- TheFridge

im confused, how is my setup different than for what the outlet was intended?
it's an outlet that has 240v and 110v sockets, how could it NOT be used for both 240v and general purpose at the same time?

the diagram is from an air conditioning website for AC units that pull both standard voltage and high voltage at the same machine, so I'm confused as to your reply.

 

I would put a 2 pole 30A breaker in the panel, run 10/3 w/ground to a sub panel in the shop. Then run the necessary circuits from there. Or, better yet, step it up to 8/3 and a 40A breaker. If you are going to the effort, might as well think ahead for future needs.

 

AFAIK, in order to use that type outlet, you need a 3 conductor wire that can carry 2 or more circuits (not sure of terminology what I mean is 3 hots, a neutral and ground). In this case, it would be 2 circuits supplied by one double pole (240V) and single pole (120V) breaker.

If you don't have enough room, why not install a small subpanel or see if you can free up some slots using split 120 v breakers?

BTW 10 gauge wire is rated for 30A up to 5HP motors why would you use that on a 20A circuit?

As always, my advice is : CHECK WITH AN ELECTRICIAN, not LJ's.

 

I agree with sawdustdad but go big or go home in my book. I have found you almost never have enough power over time.
To me, running all this convoluted wiring to enable the use of one 240 VAC item is workable, but shaky and limits your future.

If you have four slots in your main breaker box, and that box is a standard 200 amp residential box, I would simply put in a 60 amp 240 VAC breaker, (two slots), run a single wire, 240VAC 6/3, (or 6/4 if you don't have a separate ground spike in the garage) to a sub panel, and that will give you about 60 amps of whatever power you want at the sub panel inside the shop.

You can run 120 VAC circuits and 240 VAC circuits safely from that sub depending on how many slots are in the sub. And it probably would pass code. Most of the usual ones I have seen are 8 slots. That is twice what you are trying to work with now. You'll spend the money now, or spend the money later.

I'd run the heavier wire, especially if it is more difficult run, since you don't want to run out of power at a later date and have to run that wire all over again.

 

While it will function as you diagrammed, it's not safe (nor code compliant) to have 120V and 240V loads on the same circuit. If you're out of space in your panel, use one of the slots to install a subpanel for the shop. Use 8AWG wire and a 40A breaker so you'll have plenty of capacity in the shop area. 8AWG is a huge pain to work with, but it's not impossible.

 

While it will function as you diagrammed, it s not safe (nor code compliant) to have 120V and 240V loads on the same circuit. If you re out of space in your panel, use one of the slots to install a subpanel for the shop. Use 8AWG wire and a 40A breaker so you ll have plenty of capacity in the shop area. 8AWG is a huge pain to work with, but it s not impossible.

- jonah

There is no code restriction of having 120V and 240V loads on the same circuit. The main thing is the 240V and 120V outlets be the same amp rating which in this case is 20A max. The breaker must be a double pole common trip breaker if serving both line-to-line and line-to-neutral loads. The problem is if this is a garage or shop with the floor at or below grade the 120V outlets need to be GFCI protected and that is a problem with a multiwire branch circuit. GFCI cannot share a neutral.

 

I will suggest this. Have a dedicated circuit for the following,,,,, Table saw, compressor, well heck every large standalone!

 

When you put a 2 pole breaker on a single 110 volt circuit, you run the risk of the breaker not triping. The breakers are tied together with a tie bar and an internal connection.Each recptical should be controlled by an individual breaker to be right. If you cut the tie bar on the 2 pole breaker the 220 circuit might not trip. All being said It will work but its not ithe right way to do it. Personally I'd wire the 220 on a circuit by itself and clear up another space by using more half or thin breakers for the 110 circuit and everything would be right.
Gerald

 

When you put a 2 pole breaker on a single 110 volt circuit, you run the risk of the breaker not triping. The breakers are tied together with a tie bar and an internal connection.Each recptical should be controlled by an individual breaker to be right. If you cut the tie bar on the 2 pole breaker the 220 circuit might not trip. All being said It will work but its not ithe right way to do it. Personally I d wire the 220 on a circuit by itself and clear up another space by using more half or thin breakers for the 110 circuit and everything would be right.
Gerald

- alittleoff

I believe you are mistaken about there being "an internal connection" because 2 pole breakers are designed so that if one leg trips both will trip. Another common example is when 12/3 wire is run to wire separate circuits for a dishwasher and garbage disposal from the same duplex outlet where the bond is broken on the hot side and the neutral is shared. This is to make the entire box cold if one appliance trips. If separate single pole breakers are used, they are required to have a bar that ties them together which is the same thing a double pole breaker does.

 

As always, my advice is : CHECK WITH AN ELECTRICIAN, not LJ s.

- rwe2156

17 years. Just saying.

I'll dig up the article. Might take a bit.

 

If I read you properly, you want to leverage a 10/3 to have both 120 & 240 in same line. As long as not using both at same time would work. Depending on municipality, that would be frowned upon as they want singles.

I have a 10/3 for my TS as it needs 120 & 240, and I wanted a 20A outlet for my hand tools that draw a lot. Unfortunately my basement shop (prebuilt) only has 15A outlets. Your problem is going to be you won t be able to find 30A outlet for 120. At least I could not.

- bonesbr549

You are correct in assuming that 30 amp breakers require 30 amp outlets. However, in a previous LJ forum it was pointed out that some (perhaps most?) jurisdictions also interpret the code to be that you can only have one 30 amp outlet per 30 amp breaker. But you may still want to run 10/3 wire with a 20 amp breaker if you need both 120 and 240 going to the same machine to keep the loads balanced. I use this configuration for my lathe where 240 supplies the VFD and each 120 leg supplies a duplex outlet for lights and a hand sander. The lights pull juice from one leg and the sander pulls juice from the other. The neutral is shared.

 

Here's one. Branch circuits- 210.4© a multi wire branch circuit shall supply only to neutral loads.

The exceptions don't apply. This is the first one I found that said no.

 

You guys do not know what you are talking about.

When you put a 2 pole breaker on a single 110 volt circuit, you run the risk of the breaker not triping. The breakers are tied together with a tie bar and an internal connection.Each recptical should be controlled by an individual breaker to be right. If you cut the tie bar on the 2 pole breaker the 220 circuit might not trip. All being said It will work but its not ithe right way to do it. Personally I d wire the 220 on a circuit by itself and clear up another space by using more half or thin breakers for the 110 circuit and everything would be right.
Gerald

- alittleoff

A common trip double pole breaker will trip if either one of the legs exceeds the rated amperage. Two single pole breakers with a handle tie are independent trip and will trip only the one breaker that is overloaded, but they are not to be used on a multiwire circuit that supplies both line-to-line and line to neutral loads.

Here s one. Branch circuits- 210.4© a multi wire branch circuit shall supply only to neutral loads.

The exceptions don t apply. This is the first one I found that said no.

- TheFridge

Multibranch circuits can supply both line-to-line and line to neutral loads, but a common trip breaker must be used. 210-4( C ) exception #2 does apply.

 

You guys do not know what you are talking about

A common trip double pole breaker will trip if either one of the legs exceeds the rated amperage. Two single pole breakers with a handle tie are independent trip and will trip only the one breaker that is overloaded, but they are not to be used on a multiwire circuit that supplies both line-to-line and line to neutral loads.

- WhyMe

I stand corrected. Since this is the case, is there ever a time when using 12/3 wire for two 120 v circuits that a tie bar across two single pole breakers (not a single slot tandem breaker) is preferable to a common trip double pole breaker? Am I correct in assuming that if only one single pole breaker trips when a tie bar is used the second single pole breaker will still disconnect?

 

The point of using two single pole breakers with a handle tie is so if one breaker trips it doesn't also trip the other breaker. The handle tie is for the disconnect requirement for servicing.

 

I would like for all you naysayers who say the configuration is inadvisable or dangerous to show me where it violates the NEC or is in any way unsafe. I have seen this configuration done before and plan to use it in my new shop. Just because you haven't seen it before, don't assume it is incorrect. If it were unsafe or illegal, do you really think that a huge company like Leviton would make such a receptacle?

 

More precisely it doesn't say it can't be done not necessarily that it can. It's kinda grey. I thought I found something at one time that told me I couldn't do it (when trying to do something exactly like the OP mentions, on a job)

I viewed that article as either or and not both at first. Apparently this is a widely discussed topic hell, it'll make rewiring my shop easier.

Edit: One listed duplex 6-20 is a different than supplying 2 or 3 different voltage type recepts on multi wire circuit.

The breakers have to have to be tied in some fashion regardless so I don't really think there's any issue whatsoever with that.

2nd edit: I just noticed that combo recept. If I did, the only thing I would've would be "awesome". I plan on getting me a couple myself. It's a listed assembly I assume. I was thinking along the line of receptacles 2 different voltages.

 

The point of using two single pole breakers with a handle tie is so if one breaker trips it doesn t also trip the other breaker. The handle tie is for the disconnect requirement for servicing.

- WhyMe

So in the example above, if the garbage disposal trips the dishwasher still works?

 

Voltage differences aren't a problem until they exceed 300V, then a barrier is needed between devices. This is not a concern with 120/240V single phase.

 

The point of using two single pole breakers with a handle tie is so if one breaker trips it doesn t also trip the other breaker. The handle tie is for the disconnect requirement for servicing.

- WhyMe

So in the example above, if the garbage disposal trips the dishwasher still works?

- Roy Turbett

Exactly.

 

I would like for all you naysayers who say the configuration is inadvisable or dangerous to show me where it violates the NEC or is in any way unsafe. I have seen this configuration done before and plan to use it in my new shop. Just because you haven t seen it before, don t assume it is incorrect. If it were unsafe or illegal, do you really think that a huge company like Leviton would make such a receptacle?

- ArtMann

When I wired my lathe using 10/3 wire with 240v going to the VFD and 120v going to the lights and accessory outlets I had several friends express a concern that this could interfere with the operation of the VFD because of the potential for additional loads leading to a trip. Thus far I haven't had a problem but I'm only running a 1 hp motor on my lathe that also has a reeves drive to help reduce the load. However, if I were to upgrade to a larger motor I would reconsider my choice. If I were to start over, I'd use two strands of 12/2 wire and keep everything separate for the above reason and also because 10/3 romex is such a pain to work.

As for the legal issues, I think some of the confusion comes from using 12/3 wire for two circuits using a 240v/120v combination (which is what the Leviton receptacle does) vs using 12/3 wire for two circuits using a 120v/120v combination on a standard 120v duplex outlet where the common hot bus has been broken and the neutral is shared. The former is not a problem because each 120v leg occupies a separate slot with the 240v breaker in the panel. However, the second situation is problematic if a tandem breaker (two 120v breakers sharing a single slot) is used because two hot wires cannot share a neutral in a single slot. In this situation a 240v common breaker or two 120v single breakers in their own slots with a tie bar between them is required.

 

You can have a multiwire branch circuit with your 10/3 wire allowing you 1×220v and 2×110v with each hot sharing the neutral.

You can use the 110's simultaneously with the 220 respecting the amperage limit of your circuit.

I would echo though that a 30amp breaker with your 10/3 feeding a subpanel may be more practical and give you more potential capacity.