2 circuits through one wire?

[Boyd Who]

I had a buddy tell me that I could run my garage off 2 breakers on the house panel, but only use one cable out to the actual garage from the panel. Something about a 3-wire run and splitting it in a junction box in the garage.

My plans are to have two 20-amp circuits for the garage. One would power 3 outlets and 3 FL lights, the other would power 3 more outlets and the other 3 FL lights.

I don't need 220 in this garage, but want something better than the current 15 amp service to it. Right now there's only 2 outlets and 4 FL lamps.

Is this possible?

 

[walrus]

I had a buddy tell me that I could run my garage off 2 breakers on the house panel, but only use one cable out to the actual garage from the panel. Something about a 3-wire run and splitting it in a junction box in the garage.

My plans are to have two 20-amp circuits for the garage. One would power 3 outlets and 3 FL lights, the other would power 3 more outlets and the other 3 FL lights.

I don't need 220 in this garage, but want something better than the current 15 amp service to it. Right now there's only 2 outlets and 4 FL lamps.

Is this possible?

Yes this is possible, its called a multiwire branch circuit. Its legal in the US not sure about Canada. You use a 2 pole breaker, hook your 2 hots to the breaker and share a neutral between the 2 hots. You would use a piece of 12/3 nm or pull 1 black, red and white(along with a ground) in a piece of pipe.

 

[Boyd Who]

Cool, thanks. I'll check with the local electrician on Monday about doing this. I really want to upgrade my little garage before winter.

 

[mrb]

Is the garage detached? If so, in the USA you cant run more than one circuit without installing a subpanel at the garage. (there are a few exceptions, such as if you have a light on a second circuit which is switched at the house).

 

[Git]

If you overload one of your two circuits and the breaker trips - your going to have to walk over to the main panel to reset it?

Sub panels are very cheap - I did a quick search at Lowes.com

For less then $50, you can buy a small sub panel to install in the garage and run several different circuits. The panel above cost $15

Sub panel is the way to go

 

[kbs2244]

When I do it, I put the two hots on either side of the panel and the outlets are two duplexs, one for each circuit, in a 4x4 box.
That way have a quick way to just plug into the outlet next to the one you blow and finish the job before going to reset the breakers.
I have always heard them called "Edison circuits."

 

[nate379]

The water heater at my old house was wired like that. I guess each breaker controlled one element? Nothing was marked and I was doing some plumbing work. Drained the water heater after turning off 1 breaker (did thing it was odd to have a 120v water heater, but whatever).

Luckily I went back in the house not long after to grab something before running to get parts because the T&P valve had opened up dumping steam out.

 

[mrb]

When I do it, I put the two hots on either side of the panel and the outlets are two duplexs, one for each circuit, in a 4x4 box.
That way have a quick way to just plug into the outlet next to the one you blow and finish the job before going to reset the breakers.
I have always heard them called "Edison circuits."

if you are sharing a neutral, you need to use two adjacent breakers, not ones across from eachother, and the breakers need a handle tie.

 

[walrus]

if you are sharing a neutral, you need to use two adjacent breakers, not ones across from eachother, and the breakers need a handle tie.

Thats 2008 code, depends if they're on that or not

 

[mrb]

Thats 2008 code, depends if they're on that or not

regardless of the handle tie, breakers directly across from eachother will be on the same phase and cannot share a neutral

 

[Falcon67]

Thats 2008 code, depends if they're on that or not

If you don't split the circuit across both buses in the panel, seems to me you will be overloading the neutral when both circuits start to pull some good load. IE - danger condition. And when you want to service one of those outlets or circuit, you want BOTH legs OFF, otherwise you might get an unpleasant surprise.

 

[walrus]

If you don't split the circuit across both buses in the panel, seems to me you will be overloading the neutral when both circuits start to pull some good load. IE - danger condition. And when you want to service one of those outlets or circuit, you want BOTH legs OFF, otherwise you might get an unpleasant surprise.

Yes, the circuit needs to be on both legs but until 2008 code you didn't have to have a handle tie, it could be on 2 single pole breakers. Its up to the person working on the circuit to make sure its off and no danger is present

 

[tfi racing]

If you will be going to the hassle and expense of trenching and running conduit and wire to your detached,it makes more sense to go to a larger service for only a few dollars more.I wouldn't use anything less than 10/3,8 or 6g would be even better.The subpanel then can be a future option,even if you don't feel you have a need for it now.You will need a two pole breaker,or the handles tied on a wafer type breaker.

 

[Boyd Who]

Thanks for all the info. Even more confused now than before! lol
I have a subpanel that I can use, but I really don't think it's necessary.
The garage is detached and already has 110V running underground to it off a 15-amp breaker in the house. The most I plan to power out there is my small compressor and Lincoln MigPak 145, plus some lights.
I'll run over and talk to an electrician I know on Monday.

 

[Charles (in GA)]

As MRB noted, in the US you cannot have more than one circuit supplying the detached building. Don't know about Canada. Decent sized feed and the sub panel are the way to go.

Charles

 

[sberry]

Yes, trash the existing circuit and run a new one.

 

[hetkind]

I would consider that a poor wiring practice, basically you are pulling a single 220v circuit with a center tap. Far better to pull a heavier wire to a sub panel OR run two compeletely seperate circuits. Now you also have to look at the OSHA lockout/tagout standards, 29 CFR 1910.147 and subpart S and see that is would not be allowed in industry.

Right now my shop is being wired with a dedicated 400 amp service to a four hundred amp meter meter socket to two two hundred amp panels.

Howard

 

[walrus]

I would consider that a poor wiring practice, basically you are pulling a single 220v circuit with a center tap. Far better to pull a heavier wire to a sub panel OR run two compeletely seperate circuits. Now you also have to look at the OSHA lockout/tagout standards, 29 CFR 1910.147 and subpart S and see that is would not be allowed in industry.

Yeah right, it used in commercial apps all the time. It saves wire , saves current carrying conductors in a pipe and is perfectly legal. Tough to LOTO a 2 pole breaker

 

[Charles (in GA)]

Yes, the circuit needs to be on both legs but until 2008 code you didn't have to have a handle tie, it could be on 2 single pole breakers. Its up to the person working on the circuit to make sure its off and no danger is present

2005 code also required the handle tie if the circuit supplied "more than one device or equipment on the same yoke....." The 2008 code simply makes this requirement mandatory in all multiwire installations, not just most of them.

Its simply good practice

Note that a multiwire circuit cannot be used to supply 240 current. Code says it only can supply line to neutral loads, which equates to 120v loads (you could always disconnect the neutral at both ends and tie it back and use the two hots for a 240 circuit), but you could not use the multiwire circuit to supply both 120v and 240v loads. (you could....., but code doesn't allow it).

Also note that the neutrals have to be wired such that removing a device (such as a defective receptacle for replacement, for example) does not interrupt the neutral.............. Thus all neutrals need to be connected together and then pigtailed to receptacles and other loads.

Charles

 

[mrb]

Note that a multiwire circuit cannot be used to supply 240 current. Code says it only can supply line to neutral loads, which equates to 120v loads (you could always disconnect the neutral at both ends and tie it back and use the two hots for a 240 circuit), but you could not use the multiwire circuit to supply both 120v and 240v loads. (you could....., but code doesn't allow it).

Interesting -I wasnt aware of that one.

 

[walrus]

2005 code also required the handle tie if the circuit supplied "more than one device or equipment on the same yoke....." The 2008 code simply makes this requirement mandatory in all multiwire installations, not just most of them.

Its simply good practice

I agree its good practice but wasn't code. I use multiwires when the need arises. I'll be using them in my shop and I use them in the field.

 

[sberry]

I almost always tied the breakers or used a double pole. I use multi wires on occasion especially with long runs where they might get heavier draws.