12/3 cable need a double pole breaker?

[Number22]

Say I'm running a 12/3 cable to install two seperate dedicated 20A 120v outlets, with a shared neutral. When you share a neutral like that, does that mean the cable needs to be hooked up to a 20A double pole breaker? Or can I use two individual 20A breakers?

 

[walrus]

double pole breaker in 2008 code

 

[Number22]

Does it make any difference if I run THHN instead of 12/3? Or is it the "shared neutral" that makes the code?

 

[Charles (in GA)]

Double pole breaker with the handles tied together.

Its the shared neutral which creates a circuit called a multi-wire or Edison multi-wire circuit, doesn't matter how its wired, romex or conduit and THHN wire, same difference. They want both hots to trip if one does. Also insures that you are using both busses or "phases" of the panelboard. With two separate breakers, improperly installed, both on the same side of the buss (electrically), you would overload the neutral.

Neutral must be wired so the removal of a receptacle does not interrupt it (code), thus it must be pigtailed. Cannot just run the neutral in and out of one receptacle and off to the next.

Charles

 

[walrus]

Does it make any difference if I run THHN instead of 12/3? Or is it the "shared neutral" that makes the code?

Its the shared neutral

 

[rockwithjason]

double pole breaker in 2008 code

can you tell me what section that is in? I want to make a note of it for when our AHJ changes over to the 2008 code.

 

[walrus]

can you tell me what section that is in? I want to make a note of it for when our AHJ changes over to the 2008 code.

210.4(b), each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates.

 

[oleguy]

that has been code from the 1980's.don't have to wait for ahj what ever that is.it has been there all along.

 

[oleguy]

number22!sounds like you are just getting going doing electrical work.if so there is a good book for you.practical electrical wiring by herbert p. richter and creigton schwan.you can get one at most book stores.

 

[walrus]

that has been code from the 1980's.don't have to wait for ahj what ever that is.it has been there all along.

No it hasn't, it said if it was going to the same yoke it had to have a 2 pole breaker, if it wasn't going to the same yoke you could use 2 single poles.

 

[oleguy]

but if you used two single pole breakers you had to use handle ties.

 

[oleguy]

the oldest book i have is 93.and it say's same as your 2008 book.so it isn't anything new.not trying to be a jerk.just like a good spirited conversation....mike

 

[Charles (in GA)]

Walrus is correct. 2005 code said that when "a multiwire circuit supplies more than one device or equipment on the same yoke, a means shall be provided to disconnect simultaneously all ungrounded conductors........ "

The 2005 codes wording was a complete revision of earlier code (which I do not have, but it has a revision bar next to it) This statement leaves open that if the multiwire circuit does NOT supply two different devices on the same yoke, that separate breakers, not connected to trip together, could be used.

2008 code is again revised, simply stating "Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates." leaving no doubt about the intention of the code, that all multiwire circuits installed under the 2008 code must use breakers that trip open both hot circuits.

Charles

 

[oleguy]

i will go with that.although since the middle 80's,every place i have worked,inspectors wanted double pole breakers.it is a lot safer.

 

[Charles (in GA)]

Backing up further, 2002 code reads like 2005 code but is preceded with a "In dwelling units...." leaving it open that multiwire circuits supplying two devices on the same yoke, but NOT in a dwelling, did not have to have the simultaneous trip.

That is the oldest version NFPA will allow me to access online.

Charles

 

[Charles (in GA)]

Over the summer i noticed the rear portside bag would always fill very slow.
after doing a little research i found that my system uses one big pump to fill all the bags. so why would only one bag fill slow.
ow yea this is on a 2005 xlv with gravity 3 ballast system.

SPAM moderators notified.

Text unrelated to the discussion at hand and links to koozies at the bottom of the post, and post number one by the "member"

Charles

 

[Charles (in GA)]

i will go with that.although since the middle 80's,every place i have worked,inspectors wanted double pole breakers.it is a lot safer.

No argument there, it only makes sense.

Charles

 

[walrus]

i will go with that.although since the middle 80's,every place i have worked,inspectors wanted double pole breakers.it is a lot safer.

They can want what they want, they're supposed to enforce the rules

 

[oleguy]

never saw any problem with doing it.but now you have to do it that way any how.

 

[oleguy]

They can want what they want, they're supposed to enforce the rules

true enough,but as long as safety was not compramised,and nothing against it in the code they were home free.

 

[Torque1st]

The oldest code I have access to presently is the 1984 NEC which reads:
_In dwelling units a multiwire branch circuit supplying more than one device on the same yoke shall be provided with a means to disconnect simultaneously all ungrounded conductors at the panelboard where the branch circuit originated.
_Multiwire branch circuits shall supply only line to neutral load.
--Exception No.1: A multiwire branch circuit that supplies only one utilization equipment.
--Exception No.2: Where all ungrounded conductors of multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device.

 

[Charles (in GA)]

The oldest code I have access to presently is the 1984 NEC which reads:
_In dwelling units a multiwire branch circuit supplying more than one device on the same yoke shall be provided with a means to disconnect simultaneously all ungrounded conductors at the panelboard where the branch circuit originated.
_Multiwire branch circuits shall supply only line to neutral load.
--Exception No.1: A multiwire branch circuit that supplies only one utilization equipment.
--Exception No.2: Where all ungrounded conductors of multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device.

Those exceptions still exist under a paragraph (C) which says you can only have line to neutral loads. I guess the exception allows me to tap line to line (240V) off of the circuit if I wanted to.

Charles

 

[Number22]

Also insures that you are using both busses or "phases" of the panelboard. With two separate breakers, improperly installed, both on the same side of the buss (electrically), you would overload the neutral.

Right - that's probably the main reason for the code. My shop is actually 3 phase and I found mutiple existing breakers overloading neutrals like that.