Nec 240.15 overcurrent devices

Jpflex

Jpflex

Electrician big leagues
Location
Victorville
Occupation
Electrician commercial and residential
240.15 B says circuit breakers must open all ungrounded conductors both manually and automatically, unless permitted in B1, B2, b3, b4

B2 says single pole breakers can serve multi wire branch circuits for line to neutral loads if the breakers have identified handle ties.

However if the ring or tie is available but not installed they still serve as single pole breakers.

Nec does not say the handle ties must be mechanically connected so why require special breakers at all?

if the intent is to disconnect all ungrounded conductors then why not just us 2 pole breakers?

2 same for single phase circuits line to line loads

3 same for 3 and 2 phase systems with ground
 
You can use 2 or 3 pole breakers instead of handle ties for MWBCs but the code doesn't require it.

A handle tie is a mechanical connection between the handles of more than one breaker. But it may or may not turn off the other handles if one breaker trips. Many of the manufacturer supplied handle ties I've seen allow one breaker to be in the tripped position while another is on or off, but not one to be on while another is off. So, using handle ties often means that if one pole is turned off manually, all poles get turned off, but if one pole trips the others stay on. Using a 2-pole breaker means that if one trips the customer loses power to all of them.
 
The intent is to open all ungrounded poles when manually operated.

You certainly may use 2- and 3-pole breakers when handle ties are required.
 
Jpflex said:
240.15 B says circuit breakers must open all ungrounded conductors both manually and automatically, unless permitted in B1, B2, b3, b4

B2 says single pole breakers can serve multi wire branch circuits for line to neutral loads if the breakers have identified handle ties.

However if the ring or tie is available but not installed they still serve as single pole breakers.

Nec does not say the handle ties must be mechanically connected so why require special breakers at all?

if the intent is to disconnect all ungrounded conductors then why not just us 2 pole breakers?

2 same for single phase circuits line to line loads

3 same for 3 and 2 phase systems with ground
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In general a multipole breaker will be more expensive than single pole breakers with handle ties.
 
jaggedben said:
Until you count the extra trip to come back with handle ties because those are never on the truck. 😄
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With breakers that have holes in the handles, I have been known to use 6-32 screws and nuts :)
With one major brand of identified handle ties, the screws work much better than that brands handle tie.
 
jaggedben said:
You can use 2 or 3 pole breakers instead of handle ties for MWBCs but the code doesn't require it.

A handle tie is a mechanical connection between the handles of more than one breaker. But it may or may not turn off the other handles if one breaker trips. Many of the manufacturer supplied handle ties I've seen allow one breaker to be in the tripped position while another is on or off, but not one to be on while another is off. So, using handle ties often means that if one pole is turned off manually, all poles get turned off, but if one pole trips the others stay on. Using a 2-pole breaker means that if one trips the customer loses power to all of them.
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Yup . 210.4(b)says all fbe ungrounded conductors must have the ability to be simultaneously disconnected , doesn’t say anything about a common trip
 
For the purpose of the journeyman test, it seems tedious to memorize which circuits can use single pole breakers and i dint see the purpose entirely of this code
 
So beyond Multiwire branch circuits with shared neutrals, is it okay to use three single pole breakers with handle ties for a 3-ph 208V circuit? I have a situation where there are tons of spare single pole breakers in a SqD NQ panelboard, and a 3-pole 20A breaker is $265 at my local supplier, where the handle tie kit is like $20.

240.15(B)(3) seems to say this is fine for 208Y120 3ph circuits.
 
Jpflex said:
However if the ring or tie is available but not installed they still serve as single pole breakers.

Nec does not say the handle ties must be mechanically connected so why require special breakers at all?
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I think you have something screwed up there. If a handle tie is used on two single pole breakers, they ARE mechanically connected by the HANDLES. But they are not "common trip", which is a DIFFERENT issue unrelated to, and unnecessary for, MWBCs.

In an MWBC, each HOT circuit is only REQUIRED to be an individual single pole breaker. They can trip individually. The handle ties are simply there so that if someone needs to WORK ON either part of an MWBC, they are forced to turn the breakers off for BOTH parts. If not, the shared neutral is still energized in the one you are working on and is therefore dangerous.

The same effect will happen if you were to use a 2 pole breaker of course, it's just not required. A 2 pole breaker, has BOTH internal trip AND has the handles tied, but for an MWBC, you only needed the handle tie part. Where this comes into play more is when you get to using QUAD breakers. In a Quad (two tandems side-x-side), only the two inner poles can have a common trip. But the two outer poles can still be used with handle ties. So the outer poles can still be used for an MWBC (they can only be used for some 240V circuits, but this gets into a more complex issue).
 
don_resqcapt19 said:
In general a multipole breaker will be more expensive than single pole breakers with handle ties.
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Not always when you add in the costs of the properly listed for the breaker of the handle tie. Some MFG are not even available. Last several I've gotten have been about $10, SP breaker $6, 2P breaker 18$, so to handle tie a breaker costs $4 dollars more than a 2P breaker.

Added: As other noted maybe the 3PH breakers are significantly different but on the typical installs I've dealt with cost of a 2P breaker less than making with handle ties.
 
Fred B said:
Not always when you add in the costs of the properly listed for the breaker of the handle tie. Some MFG are not even available. Last several I've gotten have been about $10, SP breaker $6, 2P breaker 18$, so to handle tie a breaker costs $4 dollars more than a 2P breaker.

Added: As other noted maybe the 3PH breakers are significantly different but on the typical installs I've dealt with cost of a 2P breaker less than making with handle ties.
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Right, 3 pole is where there is big cost savings. a 20-60A 3 pole is around $60
 
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