Multiwire branch circuits

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jap

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The reason I dont like handle ties in a panelboard is that you never know if someone tied the handles together to feed a 3 phase Delta load,,,,,,,or because its a MWBC with a shared neutral.


I think if handle ties are going to be required for a MWBC they ought to be of a significant color so that we know the handles are being tied together because it is a MWBC and sharing a neutral.

From that point we automatically know that the intention of the handle tie is because of the individual circuits sharing a neutral.

If you have any expirience at all, common sense will tell you to assume that a neutral "Always" has a load on it.

What's an amp meter going to tell you ??? Its not going to tell you anything if the lights happen to be off when your checking it but someone turns them on while your disconnecting the neutral.

Just my 2 cents worth.

Jap.
 

ActionDave

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The reason I dont like handle ties in a panelboard is that you never know if someone tied the handles together to feed a 3 phase Delta load,,,,,,,or because its a MWBC with a shared neutral..
I'm a little lost here. What three phase delta loads share a neutral?

FWIW, back in the day before the code started getting dumbed down, I would bounce MWBC circuits all over the panel, but would make sure the neutrals were grouped properly with the ungrounded conductors. Straight three phase loads are always landed on a three pole breaker.

Right now I am working on a store where the specs say "NO SHARED NEUTRALS". The pipe and box fill issues are a royal PIA. I hate to sound like a grumpy old man, and I'm not. I'll do the work the way it is speced and not sweat it. It's just sad that so much effort and resources, in my little corner of the world and the rest of the country, have to be wasted because of the hysteria that surround an easily understood wiring method.
 

don_resqcapt19

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... Straight three phase loads are always landed on a three pole breaker.
...
The code permits the use of single pole breakers with handle ties for some three phase loads. Additional restrictions on where you could do this were added to the 2011 code, but it is still a permitted installation. 240.15(B)(2)&(3).
 

jap

Senior Member
The code permits the use of single pole breakers with handle ties for some three phase loads. Additional restrictions on where you could do this were added to the 2011 code, but it is still a permitted installation. 240.15(B)(2)&(3).
That is exactly my point. In the past when you looked in a panel and saw 2 or 3 pole common trip breakers or 2 or 3 individual breaker handles tied together it meant that they were feeding a 240,208 or 480v load. Now when you look in a panel and see this you dont know if they're tied together for this reason or because they are a MWBC that share a neutral.If the Handle ties were a specific color for a (MWBC Installation Only)then you would know the reasoning was because they were sharing a neutral. and leave the Common Trip and regular handle ties for the 208,240 and 480v loads like it used to be.
 
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jap

Senior Member
I'm a little lost here. What three phase delta loads share a neutral?
They dont,,,, thats my point.

In the past when you looked in a panel and seen a 3p common trip breaker you knew it was feeding either a 3phase Delta or a 3phase Y load.

Now the 3 pole breakers may not be feeding a 3 phase load at all,,,, its probably feeding 3 single phase circuits and the 3 pole breaker is being used to satisfy the MWBC Clause.

I just dont like it.

leave the 2p and 3p common trip breakers and standard handle ties for their purpose and use something else (Marked differently) to identify that you tied the handles together because you were feeding a MWBC is all i'm saying.
 
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jap

Senior Member
I dont know about you all, but I have a hard enough time convincing people to let me unplug a single computer,much less shutting dowh 2 or 3 full circuits of lights and receptacles to do something. Usually if thats the case all the work has to be done after hours and then you pray everything comes back up afterwards.
 

Dennis Alwon

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Why would you need to know if the load was a 3 phase load or one sharing the neutral. Obviously with today's rules that is easy to tell when you open a panel.

If the panel is a high leg delta panel I doubt there would be a 3 phase tie utilizing a neutral. DP perhaps. But again why does that matter
 

hurk27

Senior Member
They dont,,,, thats my point.

In the past when you looked in a panel and seen a 3p common trip breaker you knew it was feeding either a 3phase Delta or a 3phase Y load.

Now the 3 pole breakers may not be feeding a 3 phase load at all,,,, its probably feeding 3 single phase circuits and the 3 pole breaker is being used to satisfy the MWBC Clause.

I just dont like it.

leave the 2p and 3p common trip breakers and standard handle ties for their purpose and use something else (Marked differently) to identify that you tied the handles together because you were feeding a MWBC is all i'm saying.

I don't see the problem either:? if the panel schedule has been properly marked for each load on a breaker as also required by code it would just be easy to look at the panel label wouldn't it? if they are not following code and labeling the panel schedule then why would they follow code on anything else?
 

ActionDave

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That is exactly my point. In the past when you looked in a panel and saw 2 or 3 pole common trip breakers or 2 or 3 individual breaker handles tied together it meant that they were feeding a 240,208 or 480v load. Now when you look in a panel and see this you dont know if they're tied together for this reason or because they are a MWBC that share a neutral.If the Handle ties were a specific color for a (MWBC Installation Only)then you would know the reasoning was because they were sharing a neutral. and leave the Common Trip and regular handle ties for the 208,240 and 480v loads like it used to be.
I see where you are coming from now, and I think we are in the same camp.
 

jap

Senior Member
Why would you need to know if the load was a 3 phase load or one sharing the neutral. Obviously with today's rules that is easy to tell when you open a panel.

ok, if its so obvious , tell me how you know by opening a panel and seeing a 3p common trip breaker that its feeding a 3 phase load?
You dont.

for example, lets say you had a 126 ciircuit 3 section panelboard and only had (1) true 3 phase circuit coming out of it.
all the rest were single phase loads.all 20 amp.

Used to if I was working on the 3 phase load it was easy to find in the panel since it was the only 3p common trip breaker or 3 individual breakers with the handles tied together.

now with multiwire branch circuits requiring handle ties, there's the possibility that the installer used all 3p 20a common trip breakers for all 42 3p breakers in the panel, Now finding the 3p breaker that feeds the load your working on has become more time consuming.

If the Handle Ties used for the MWBC were a specific color, and , the common trip 3p was left for the true 3ph load it would still be very easy to locate.

Not saying that this will ever become reality but thats why it makes a difference to me.
 

roger

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ok, if its so obvious , tell me how you know by opening a panel and seeing a 3p common trip breaker that its feeding a 3 phase load?
You dont.

for example, lets say you had a 126 ciircuit 3 section panelboard and only had (1) true 3 phase circuit coming out of it.
all the rest were single phase loads.all 20 amp.

Used to if I was working on the 3 phase load it was easy to find in the panel since it was the only 3p common trip breaker or 3 individual breakers with the handles tied together.

now with multiwire branch circuits requiring handle ties, there's the possibility that the installer used all 3p 20a common trip breakers for all 42 3p breakers in the panel, Now finding the 3p breaker that feeds the load your working on has become more time consuming.

If the Handle Ties used for the MWBC were a specific color, and , the common trip 3p was left for the true 3ph load it would still be very easy to locate.

Not saying that this will ever become reality but thats why it makes a difference to me.

Hmmmm, circuit tracer?

Roger
 

Strathead

Senior Member
Why would you need to know if the load was a 3 phase load or one sharing the neutral. Obviously with today's rules that is easy to tell when you open a panel.

ok, if its so obvious , tell me how you know by opening a panel and seeing a 3p common trip breaker that its feeding a 3 phase load?
You dont.

for example, lets say you had a 126 ciircuit 3 section panelboard and only had (1) true 3 phase circuit coming out of it.
all the rest were single phase loads.all 20 amp.

Used to if I was working on the 3 phase load it was easy to find in the panel since it was the only 3p common trip breaker or 3 individual breakers with the handles tied together.

now with multiwire branch circuits requiring handle ties, there's the possibility that the installer used all 3p 20a common trip breakers for all 42 3p breakers in the panel, Now finding the 3p breaker that feeds the load your working on has become more time consuming.

If the Handle Ties used for the MWBC were a specific color, and , the common trip 3p was left for the true 3ph load it would still be very easy to locate.

Not saying that this will ever become reality but thats why it makes a difference to me.


My turn to be snarky, since we are referring to today's rules. Since you are required to have an accurate panel schedule all you ahve to do is look at the panel schedule. Elementary my dear Watson!
 

jap

Senior Member
My turn to be snarky, since we are referring to today's rules. Since you are required to have an accurate panel schedule all you ahve to do is look at the panel schedule. Elementary my dear Watson!

A Panel Schedule will never tell you exactly what all your shutting down. unless it reads like a small novel.

Most Panel Schedules I've seen read give a general explanations of where they are located but doesnt show exactly what your shutting down.

For this reason in my own home I drew a circuitry diagram of all the receptacles and Lights and how they were tied together, shrunk it down and attached it to the inside of the Panel door.
That's the only type of Panel schedule I know of that's completely accurate.


unless your the only one who works in a specific panel you never know who tied what onto what after the panel schedule was made and I doubt anyone calls the inspector to verify they accurately updated the Panel Shedule after adding an addition to a circuit.
 

jap

Senior Member
Hmmmm, circuit tracer?

Roger

my point again, if the Handle ties for a MWBC were a specific color and not a common handle tie or common trip ciircuit breaker, a circuit tracer would not be needed, it would be obvious which 3p breaker was for the 3ph load and wouldnt have to waste our time with a circuit tracer.
 
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