Multi Wire OCPD

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AKsparky1

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Anchorage, Alaska
Is it permissible to land two wires on one screw (pole) of a 120/240 two pole breaker that has the manufacturer handle ties? I have an out-house. A portable one hole out house that sits on a trailer with a small generator. The generator supplies 240v to a two pole disconnect mounted on the back of the out house. the one hole outhouse has a 240v 2000kw heater (this is Alaska) and three lights and a fan. I have two 12/2c romex cables going into the disconnect. one cable is from the 240 heater and the other cable is for the lights and fan. I know that the 120/240 rated breaker is rated to supply line to neutral loads but am I in violation by supplying both line to line and line to neutral loads? Manufacturers get away with this all the time because a lot of appliances are listed as a single unit. This out house is a single unit....:D
 
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GoldDigger

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You say that the breaker comes from the manufacturer with handle tie. That does not tell us though whether it also has a common trip feature. That will affect whether it is suitable for line to line loads.
Handle ties alone are sufficient for MWBCs with only line to neutral loads.
 
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fmtjfw

Senior Member
Location
Fairmont, WV, USA
AKsparky1 said:
Is it permissible to land two wires on one screw (pole) of a 120/240 two pole breaker ....

I know that the 120/240 rated breaker is rated to supply line to neutral loads but am I in violation by supplying both line to line and line to neutral loads? Manufacturers get away with this all the time because a lot of appliances are listed as a single unit. ....:D
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It is only permissible to land two wires under a single screw if the device (or connector) is listed for that. The UL White book has a catchall classification called ELECTRICAL EQUIPMENT FOR USE IN ORDINARY LOCATIONS (AALZ) which is referenced by most other classifications (including breakers), For screw terminations it states the following:

Terminals ? Product terminals, including wire connectors and terminal screws, are acceptable for connection of only one conductor, unless there is marking or a wiring diagram indicating the number of conductors which may be connected.
Click to expand...

AALZ has lots of good stuff in it. You should download the White Book from UL.com.

As to the question about L-L and L-N loads:

100 Utilization Equipment. Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.

A unit outhouse may meet this definition. But most utilization equipments are things that are not designed to hold a person.

210.4 Multiwire Branch Circuits.
....
(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.

240.15 Ungrounded Conductors.
....
(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 handles tie, shall be permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-to-neutral loads.

So unless you want to apply exception no. 1, you need a breaker marked "common trip".

Using a common-trip breaker is the safest course.
 
Dennis Alwon

Dennis Alwon

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If you have a 2000 watt heater how will you meet art 210.19---going by memory. It states that you cannot have more than 50% load where you add lighting and receptacles. It might be 210.21
 
david luchini

david luchini

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Dennis Alwon said:
If you have a 2000 watt heater how will you meet art 210.19---going by memory. It states that you cannot have more than 50% load where you add lighting and receptacles. It might be 210.21
Click to expand...

It's 210.23...It seems to me he would meet that requirement if he's using a 20A c/b.
 
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AKsparky1

Member
Location
Anchorage, Alaska
fmtjfw said:
It is only permissible to land two wires under a single screw if the device (or connector) is listed for that. The UL White book has a catchall classification called ELECTRICAL EQUIPMENT FOR USE IN ORDINARY LOCATIONS (AALZ) which is referenced by most other classifications (including breakers), For screw terminations it states the following:



AALZ has lots of good stuff in it. You should download the White Book from UL.com.

As to the question about L-L and L-N loads:

100 Utilization Equipment. Equipment that utilizes electric energy for electronic, electromechanical, chemical, heating, lighting, or similar purposes.

A unit outhouse may meet this definition. But most utilization equipments are things that are not designed to hold a person.

210.4 Multiwire Branch Circuits.
....
(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.

240.15 Ungrounded Conductors.
....
(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 handles tie, shall be permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-to-neutral loads.

So unless you want to apply exception no. 1, you need a breaker marked "common trip".

Using a common-trip breaker is the safest course.
Click to expand...

Thank you for the response. I gues handle ties does not meet a common trip requirement.
 
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Sparky3141

Member
Location
N/A
AKsparky1 said:
Thank you for the response. I gues handle ties does not meet a common trip requirement.
Click to expand...

It sounded to me like you probably have a common trip 2 pole breaker. But to find out, do a quick internet search for the specification sheet for that make and model.

That'll also tell you if you can land 2 wires on it. But if you can't do that, you should be able to put a pigtail on it.
 
Dennis Alwon

Dennis Alwon

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I am confused also. If it is a dp breaker then it has common trip. You stated a 240/120 dp breaker with manufacturers ties. Does this mean it came from the manufacturer as one piece or did you take 2 sp breakers and make it a dp unit with factory ties that you installed?
 
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GoldDigger

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If it is a two pole breaker with one handle, it must be common trip.
But some people do not distinguish between two 1/2 size breakers in in one assembly and a two pole breaker. The former are available as independent breakers, two breakers with handle tie or common trip with handle tie.
 
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GoldDigger

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With common trip, overcurrent on just one hot (such as from a short to neutral or ground) will trip both poles.
With a a handle tie, one breaker tripping will not usually cause the other pole to open. The force and travel of the tripped handle will not activate the handle of the other section.
 
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fmtjfw

Senior Member
Location
Fairmont, WV, USA
crtemp said:
what is the difference between common trip breakers and breakers with handle ties?
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All the breakers you find in building are "trip-free", that is, if you hold the handle in the ON position, the breaker will still operate to clear a fault or overload. [Some breakers in submarines may not be trip-free so you can hold a circuit closed during being depth charged.]

A multi-pole breaker marked common trip will trip all poles if one trips.

Two or three single pole breakers with their handles connected by listed handle ties, let alone a nail or piece of #12 CU may well not trip the other poles if one pole trips. The tripped position of the handle is midway between OFF and ON, and may not even move if, for instance, the center pole of three poles trips, being held by the two outermost handles.
 
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