Another quick wiring question

[Charles (in GA)]

You can not use 2 single pole breakers to feed one 14/3. To feed 14/3 you have to use a 2 pole breaker where the two switches are mechanically connected (second picture). Its the same type of breaker that is used on 240V circuits.

2011 NEC 240.15(B) specifically allows individual single pole breakers to be used for MWBC, PROVIDED that "identified" handle ties are used, AND if the MWBC only supplies line to neutral loads (120V only).

Finding the correct handle ties is probably more trouble and expense than simply using a double pole common trip breaker, but its not an absolute requirement.

By the way, nails pushed thru the holes in the handles and bent over DO NOT count as an "identified" handle tie.

Charles

 

[pattenp]

In all due respect I don't agree with this. I've done a lot of researching on this topic and come to the conclusion that handle ties are required on single pole breakers protecting a MWBC per NEC 2011. Here is one Mike Holt forum discussion on MWBC.

http://forums.mikeholt.com/showthread.php?t=138898&highlight=multiwire+branch+circuit

as long as that single pole breaker is identified they don't have to be tied together if they are sharing a neutral

it is still NOT illegal to use 2 single pole breakers for a 14-3/12-3.

 

[Charles (in GA)]

as long as that single pole breaker is identified they don't have to be tied together if they are sharing a neutral

it is still NOT illegal to use 2 single pole breakers for a 14-3/12-3.

You need to read the 2011 code, the HANDLE TIE is what has to be "identified", meaning the manufacturer approved, designed for that use, handle tie.

There is nothing to prohibit the use of a double pole common trip breaker on a MWBC. If there is, please quote the code section.

Charles

 

[Charles (in GA)]

210.4 Multiwire Branch Circuits.
(A) General. Branch circuits recognized by this article shall be permitted as multiwire circuits. A multiwire circuit shall be permitted to be considered as multiple circuits. All conductors of a multiwire branch circuit shall originate from the same panelboard or similar distribution equipment.

Informational Note: A 3-phase, 4-wire, wye-connected power system used to supply power to nonlinear loads may necessitate that the power system design allow for the possibility of high harmonic currents on the neutral conductor.

(B) Disconnecting Means. 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.

Informational Note: See 240.15(B) for information on the
use of single-pole circuit breakers as the disconnecting
means.

(C) Line-to-Neutral Loads. Multiwire branch circuits shall supply only line-to-neutral loads.

Exception No. 1: A multiwire branch circuit that supplies only one utilization equipment.

Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device.

Informational Note: See 300.13(B) for continuity of grounded conductor on multiwire circuits.

(D) Grouping. The ungrounded and grounded circuit conductors of each multiwire branch circuit shall be grouped by cable ties or similar means in at least one location within
the panelboard or other point of origination.

Exception: The requirement for grouping shall not apply if the circuit enters from a cable or raceway unique to the circuit that makes the grouping obvious.

The above is telling us to use common trip, but is not specific as to how. The informational note it just that, information as to where to find other information, but is not mandatory in nature. Otherwise it would not be called an informational note.

240.15 Ungrounded Conductors.

(A) Overcurrent Device Required. A fuse or an overcurrent trip unit of a circuit breaker shall be connected in series with each ungrounded conductor. A combination of a current transformer and overcurrent relay shall be considered equivalent to an overcurrent trip unit.

Informational Note: For motor circuits, see Parts III, IV, V, and XI of Article 430.

(B) Circuit Breaker as Overcurrent Device. Circuit breakers shall open all ungrounded conductors of the circuit both manually and automatically unless otherwise permitted in
240.15(B)(1), (B)(2), (B)(3), and (B)(4).

(1) Multiwire Branch Circuits. Individual single-pole circuit breakers, with identified handle ties, shall be permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-to-neutral loads.

This is telling the inspector that separate single pole breakers with identified handle ties are OK, but it is not mandating the use of separate breakers. (as opposed to using a double pole breaker)

ARTICLE 100, Definitions

Identified (as applied to equipment). Recognizable as
suitable for the specific purpose, function, use, environment,
application, and so forth, where described in a particular
Code requirement.

Informational Note: Some examples of ways to determine
suitability of equipment for a specific purpose, environment,
or application include investigations by a qualified testing
laboratory (listing and labeling), an inspection agency, or other
organizations concerned with product evaluation.

 

[kyle242gt]

What I find intriguing about this, as a layman, is how much verbiage there is in the code... seemingly only to obscure understanding.

All the more reason to run two 14/2's. Unless there's a prohibition to running two feeds to a plastic four-gang box, on Saturdays, in California.

 

[rwreuter]

You need to read the 2011 code, the HANDLE TIE is what has to be "identified", meaning the manufacturer approved, designed for that use, handle tie.

There is nothing to prohibit the use of a double pole common trip breaker on a MWBC. If there is, please quote the code section.

Charles

i did read it, and that is what i meant....i even quoted that section in the NEC....i thought it was obvious as to what i was referring to.

don't forget....the AHJ will determine what is approved. one may say it absolutely have to be from that manufacturer and another may say as long as it is readily identifiable it is good.

the AHJ is the goo here.

as long as it is identified (AHJ will say what identified is or what is approved) it is good.

this is a far cry from what pattenp was saying earlier:

"If you use two single pole breakers on a MWBC you are in violation of NEC 210.4(B) You have to put handle ties on the two singles to comply with code."

 

[rwreuter]

What I find intriguing about this, as a layman, is how much verbiage there is in the code... seemingly only to obscure understanding.

All the more reason to run two 14/2's. Unless there's a prohibition to running two feeds to a plastic four-gang box, on Saturdays, in California.

OH NO!!! not another. just kidding

1. make sure the grounds are all tied together.

2. ensure the neutrals are separated.


the NEC can be confusing....people can know how to wire a house, but to understand the NEC is another thing. i have known good electricians that take the NEC test over and over and over and over and just can't pass it.

the basics stay the same but the NEC changes, some for the good and some for the bad.

i got lucky, i passed it the first time around.....somewhere back in 1997. fortunately, i don't work in that career field any longer....i went to something easier.....Air Frame and Power Plant mechanic or A&P mechanic on aircraft.....LOL (besides, it pays better)

 

[pattenp]

Just as you said, you thought what you said was obvious. I thought what I said was obvious. Instead of saying "If you use two single pole breakers on a MWBC you are in violation of NEC 210.4(B) You have to put handle ties on the two singles to comply with code." , I should have said, If you use two single pole breakers to protect a MWBC without using identifying handle ties you are in violation of NEC 2011 210.4(B).

One thing is obvious, you have your interpretation of the code and I have mine.

i did read it, and that is what i meant....i even quoted that section in the NEC....i thought it was obvious as to what i was referring to.

don't forget....the AHJ will determine what is approved. one may say it absolutely have to be from that manufacturer and another may say as long as it is readily identifiable it is good.

the AHJ is the goo here.

as long as it is identified (AHJ will say what identified is or what is approved) it is good.

this is a far cry from what pattenp was saying earlier:

"If you use two single pole breakers on a MWBC you are in violation of NEC 210.4(B) You have to put handle ties on the two singles to comply with code."

 

[rwreuter]

WHATEVER DUDE!!!!

to the guy that started this thread...hopefully you got your question answered.

as i said, you can run a 14-3, at the panel, stack two breakers as to ensure they are on different phases...black wire to the top breaker and red wire to the bottom breaker.

IT IS NOT IN VIOLATION OF SQUAT.

talking with people about this that do not have a license (or have NOT had formal training and to people that have not taken years of CEU's) and have not done this for a living is futile at best.

 

[pattenp]

rwreuter, I may be wrong, but because you may have a license and formal training does't mean you're right. Code has changed since 1997. This is a forum to exchange information and to learn from others. Nothing said by me was with the intention to challenge you and to prove you wrong. I look forward to more informational exchanges with you.

 

[ishiboo]

WHATEVER DUDE!!!!

to the guy that started this thread...hopefully you got your question answered.

as i said, you can run a 14-3, at the panel, stack two breakers as to ensure they are on different phases...black wire to the top breaker and red wire to the bottom breaker.

IT IS NOT IN VIOLATION OF SQUAT.

talking with people about this that do not have a license (or have NOT had formal training and to people that have not taken years of CEU's) and have not done this for a living is futile at best.

Part of being a good electrician is having some common sense... though the NEC (now, if not always) clearly requires a handle tie if single pole breakers are used, no question. It's been clearly pasted, I am not sure what there is to argue.

It also makes perfect sense - it is safer if you have two hots running in the same cable, to the same device boxes of course, to shut BOTH off at once and not just one when servicing. Even if it was not code, given this BASIC principle of servicing electrical devices, why would you NOT put the $4 handle tie in? If I am sticking my hand in a box, I want to make sure the power is off.

 

[buzz4041]

If I remember right back in 1983 when I got my license it required the handle tie then as it does now. Like ishiboo said it is a safety device to protect you when you share neutrals. To the OP don't install 14-3 unless you tie the breakers together or use a common 240 breaker simple as that. I would use 2 circuits with 14-2 so you all way's have light when needed.

 

[kyle242gt]

Yep, 14/2 x2 it is, going to use a tandem breaker... might see if I can exchange one of the extra 20 tandems the electrician had my buy a couple years ago.

 

[slacker garage shop]

Dang it how did I miss this one. Hmmm ill stay out lol

 

[Falcon67]

LOL - The 240 well pump circuit that was on our house used two 30A breakers with an identified bread tie. Take that, NEC. The utility guy upgraded that to a piece of copper. I upgraded the circuit to gone for now.

 

[kyle242gt]

The more the merrier, let's hear what you have to say! Worst case scenario it's another conflicting opinion.

I'm not overly concerned with what the inspectors have to say, I hear from my general that we have a pussycat, he's more interested in inspecting the car collection.

Though I plan on having the walls easily removable for wiring mods, I'd like to do it right, and I swear, everything so far I do, I get raised eyebrows and a "Oh wow, you can't do that!" from my electrician.

 

[slacker garage shop]

The more the merrier, let's hear what you have to say! Worst case scenario it's another conflicting opinion.

I'm not overly concerned with what the inspectors have to say, I hear from my general that we have a pussycat, he's more interested in inspecting the car collection.

Though I plan on having the walls easily removable for wiring mods, I'd like to do it right, and I swear, everything so far I do, I get raised eyebrows and a "Oh wow, you can't do that!" from my electrician.

We'll since you asked. Like the other guy said its really up to the AHJ. Around here they just started enforcing that code a couple years ago. If your sharing a neutral a common trip breaker is required. A handle tie is not excepted because it is removable . The real ***** is its supposed to be the NEC meaning NATIONAL electrical code but it's not. Every area and every inspector has there interpretation.
As a rule for the company I work for we don't share neutrals but if we have to due to conduit fill then we use a ul listed common trip breaker, nothing the inspector can hit you with regardless of how they interpret the wording.

 

[pattenp]

Here some good info on Handle Ties vs. Common trip breaker by George Gregory, Schneider Electric/Square D Co.:


Misunderstanding No. 4: Handle ties provide the same operation as internal common trip.

Handle ties provide an acceptable method of linking operating handles of several single-pole circuit breakers together so they'll switch the tied circuit breakers together. Although good reasons exist for using handle ties, such as in multiwire branch circuits, the method in which a handle tie functions is often not well understood. And in some cases, application of handle ties may lead to unnecessary hazards.

It's important to understand the difference between the handle tie feature and the common trip feature. Handle ties fasten the handles of two or more single-pole circuit breakers together. With handle ties installed, all of the poles are switched on and off together. However, if one pole trips because of an overload or short circuit, the handle tie doesn't cause the connected poles to trip. The condition can leave one pole tripped and the other tied poles energized.

Multipole circuit breakers with common trip will switch all poles on and off together. They'll also trip all poles simultaneously when an overload or short circuit occurs on any of the poles. In this case, all poles operate together regardless of whether the circuit breaker is switched manually or opens automatically because of overcurrent.

It's often impossible to determine the difference between the common trip 2-pole circuit breaker and two single-pole circuit breakers with handle ties unless you're familiar with the product design. The potential hazard arises when one pole trips and another pole remains energized. It's especially hazardous if someone assumes that all poles are tripped and open when only one pole is open.

Consider a multiwire branch circuit as described in 210.4. Handle ties are frequently used in multiwire circuits. These circuits supply only line-to-neutral loads unless they supply only one piece of equipment or unless the overcurrent device opens all conductors simultaneously (common trip). By the definition in Art. 100, multiwire branch circuits have a grounded conductor with equal voltage between it and each ungrounded conductor. When one pole trips due to overcurrent, the remaining pole(s) is connected in a closed circuit with the grounded circuit conductor.

Alternatively, consider a straight 240V circuit with no grounded circuit conductor. When one pole trips, the remaining pole(s) is energized with no return path through a circuit conductor. The pole will continue to serve the fault unless tripped or opened manually.

The fundamental requirement of 240.20(B) is that the circuit breaker shall open all ungrounded conductors of the circuit. In other words, it calls for common trip. The section provides the following exceptions to allow the use of single-pole circuit breakers with handle ties:

In multiwire branch circuits

On circuits with line-to-line connected loads of grounded single-phase systems and on 3-wire DC circuits

With line-to-line loads in 3-phase, 4-wire systems and 2-phase, 5-wire systems

In light of the fact that handle ties don't provide for common trip and the fact that the fundamental requirement is for common trip, it seems most reasonable to apply only circuit breakers with common trip in the second and third items above, where line-to-line loads are served. That means eliminating those two items as exceptions.

The National Electrical Manufacturers Association (NEMA) has proposed eliminating these two items from the NEC, and the Code Making Panel is considering it. Acceptance of that proposal will require the installation of common trip circuit breakers in circuits serving line-to-line loads and require that all poles clear the circuit simultaneously.

The requirements of 240.20(B) relate only to circuit breakers. They don't affect fuse applications. The separate disconnect for fuses is quite different from the integrated functions of a circuit breaker. Many users believe all poles of a circuit breaker open when one pole opens, without fully understanding the function of handle ties. Common-trip circuit breakers are readily available and are the standard for 2- and 3-pole circuit breakers.

Handle ties have an appropriate place in providing a means for protecting multiwire branch circuits. However, they aren't a replacement for common trip and shouldn't be perceived that way.

Specifying a safe design isn't easy when you're confronted by several of the misconceptions that serve to further muddle the situation. However, taking the time to separate the truth from the myth will help you provide an environment that's not only safe for workers but reliable and low-maintenance.

Gregory is manager, industry standards, overcurrent protection for Schneider Electric/Square D, Cedar Rapids, Iowa.

 

[slacker garage shop]

Great article. Thanks for finding that and it pretty much sums things up.

 

[Charles (in GA)]

Square D is saying that because their double pole common trip breakers have only one handle. They spend extra money to make two breakers in one housing and use one handle that is internally tied to both breakers.

Saying that two handles tied together with an approved handle tie will leave one breaker tripped and one not tripped is, in my opinion, just plain wrong. He is hyping this to sell square D breakers. If you have two side by side breakers (not Square D) and the handles are joined by a pin thru the holes in the handles, or by a metal or plastic sleeve that fits over the handles, you have effectively replicated the double pole breaker of every manufacturer (except Square D QO series), with the exception that the bodies of the breakers are not riveted together.

I'd like to see how one will trip and not take the other one with it. Properly tied together it will trip both like its supposed to.

Common trip is mechanical, whether the connection is external to the breaker (handle ties) or internal (Square D QO) the trip is still mechanical. One breaker trips, and forces the other one off. I'll have to tear a Square D QO double pole apart some time and take pics.

Again, just hype. This is the same company that got all upset when Siemens came out with a 3/4 wide breaker "classified" to fit in Square D panels.

Charles

 

[ishiboo]

Great article. Thanks for finding that and it pretty much sums things up.

Agreed. Circuit breakers can no longer be "held open" in a trip condition by forcing the handle to stay where it is, which is why one trips and the other can stay closed.

The normal method of breaker trip is over current, not a short fault, so for most of the common MWBC uses two tied breakers works fine. There is a slim margin gained by disconnecting BOTH. The more likely issue is that a breaker trips, and you think its off and go to replace an outlet in a MWBC box and the other half is still live.

No matter what you do, anything is more appropriate than two unconnected single pole breakers - handle tie or double-pole breaker

 

[slacker garage shop]

Agreed. Circuit breakers can no longer be "held open" in a trip condition by forcing the handle to stay where it is, which is why one trips and the other can stay closed.

The normal method of breaker trip is over current, not a short fault, so for most of the common MWBC uses two tied breakers works fine. There is a slim margin gained by disconnecting BOTH. The more likely issue is that a breaker trips, and you think its off and go to replace an outlet in a MWBC box and the other half is still live.

No matter what you do, anything is more appropriate than two unconnected single pole breakers - handle tie or double-pole breaker

That's not really the issue (having other hot wires in the box) . The issue is if your working on the circuit that is off you still have a load on the neutral because its being shared by the circuit that is on. You open up that neutral thinking the circuit is off or not even knowing its being shared and you for issues.

 

[pattenp]

Sheez... I thought I was posting some helpful info and it's caused more controversy.

 

[kyle242gt]

Then to revisit the original question, and bearing in mind that I'm a chicken-sh!t when it comes to electricity (ie tend to power the subpanel down at the main panel before doing anything), what would the collective suggest?

Tandem on same phase? With/without tie?
Dual or double on opposite phases? With/without tie?

 

[ishiboo]

Then to revisit the original question, and bearing in mind that I'm a chicken-sh!t when it comes to electricity (ie tend to power the subpanel down at the main panel before doing anything), what would the collective suggest?

Tandem on same phase? With/without tie?
Dual or double on opposite phases? With/without tie?

MWBC must be on opposite phases, or you could easily overload the neutral.

The best is a dual-pole breaker, which will be on two phases and not need a tie.

Second best optionwould be two singles with a handle tie.

 

[kyle242gt]

I take it MWBC is a 14/3.
What if I use two 14/2s, and have separate neutrals?

 

[pattenp]

If you use two NM 14/2s and two single pole breakers you will have two run of the mill circuits. Nothing special needs to be done. This is what I've suggested from the start.

A mini/tandem single pole breaker is two single pole breakers that will fit in the space of one normal sized single pole. Don't use a tandem on a MWBC, that puts both legs on the same phase.

You use a 3wire w/g cable such as 14/3 to make up a MWBC, 2 hots and 1 shared neutral.

 

[pattenp]

If you will pay for the airfare I'll come and help you install what you need.

 

[Charles (in GA)]

I take it MWBC is a 14/3.
What if I use two 14/2s, and have separate neutrals?

Even if you use 12/2 or 14/2 and ONE single pole breaker, its not a problem, unless you are drawing more than 80% thru the breaker. You can split the circuit all you want, go all kinds of different directions with it, and its still only one circuit.

You can even "split" it at the panel, right at the breaker, on the few breakers that are approved for "double tap", such as the Square D Homeline series, or the Square D QO series (not the minatures, just the regular 3/4 inch wide single pole breakers). If you have some other kind of breaker, you can easily come off the breaker with one wire, and within a couple of inches if you want, wirenut it to two 14/2 wires going off in different directions. Its still one circuit, capable of only 15 amps and restricted to 12 amps max for lighting.

Charles

 

[scutty83]

Ha, I think you need to refine the title of your thread "Another long complicated wiring question" Good info, anyways.

 

[kyle242gt]

Haha Pat, I can't be bothered to pay my buddy $50/hr... Sorta blew the budget building the shop, repainting, repaving, remodeling upstairs bath! Been an expensive year.

Charles - that's what's got me going to two breakers. 15 fixtures at .74a doesn't leave much (any) room to add on. If I go through with the spray booth idea, I'll need another five or so. In the offchance that I leave all 20 fixtures on at once, I'll probably pop the breaker.

If I was facing having to buy more wire and so forth, I might reconsider, but what the hell, I have this roll just staring at me, daring me to find a use for it.