multiwire branch circuits

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iwire said:
Larry, you have enough knowledge to be able to work on one part of a MWBC without smoking other parts. Only qualified people should be digging that far into an electrical system. I think the new rule stinks.
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Bobert, I wasn't expressing my opinion; I agree with you. I'm a confirmed MWBC believer, and yes, I do know enough. :)
 
Why Bob?...... Why?

Why Bob?...... Why?

iwire said:
I think the new rule stinks.
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Do you have the same opinion of 210.4 (D) ?

Two changes here that reflect a saftey stance or concern being incorporated into the code. Safety being one of the root cause of most changes me thinks.

What saftey concerns with this rule bothers you? :-?
 
Please don't flame me but I think this code changes actually decreases safety by putting the electrical worker in the position of working on the circuitry energizied. i just can't see very many customers wanting 30 receptacles(or whatever is on the 3 circuits) to be turned off to do some work. I'm not saying that I agree with working on circuits energized,,, but. Use your amp clamp and proceed as needed. One of the first things I learned many years ago was not to open a neutral without checking it for load.
 
jerm said:
I think, from past posts, that most people here think the new rule stinks, however, there are a very vocal minority that think it's a good rule.

Let's start a poll and find out if I'm right or wrong.

A vocal minority post should follow this
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That neutral being shared by those other two circuits can really light you up. Esspecially with a 277 load on it.
 
Well since often you wont just find 2-3 circuits in a box - what then - shut off the whole panel - or the building?

'Shut down grid 348 - I gotta change a ballast!':D - Sorry I cant remember the line from "Towering Inferno"
 
frizbeedog said:
Do you have the same opinion of 210.4 (D) ?

Two changes here that reflect a saftey stance or concern being incorporated into the code. Safety being one of the root cause of most changes me thinks.

What saftey concerns with this rule bothers you? :-?
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This new rule will result in more live work being done. I have no doubt of that at all.

pjg said:
I think this code changes actually decreases safety by putting the electrical worker in the position of working on the circuitry energized. i just can't see very many customers wanting 30 receptacles(or whatever is on the 3 circuits) to be turned off to do some work.
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That is exactly right and will result in electricians deciding to work it hot where before they could easily shut off one leg.
 
maybe they are trying to force people to get away from sharing neutrals by making it a P.I.T.A. to do it legally.... if you want to be able to turn circuits of individually, sounds like you need to pull more grounded conductors.
 
ultramegabob said:
maybe they are trying to force people to get away from sharing neutrals by making it a P.I.T.A. to do it legally....
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If that is the plan it is shortsighted, the cost of supplies and power has only increased, sharing neutrals can reduce costs.

if you want to be able to turn circuits of individually, sounds like you need to pull more grounded conductors.
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That is the result, but more likely the MWBC will be run anyway and it will be the service electrician that gets stuck with turning off all 3 circuits.
 
It will undoubtedly lead to more hot work.

Roger
 
iwire said:
Only qualified people should be digging that far into an electrical system.
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And therein lies the crux of the problem. Seems like the CMP's are designing code sections not only to insure the safety of the general public but are now insuring the safety of all of us out there working (or having to work) circuits live for testing purposes.
I think the new rule stinks.
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I can't believe these words were actually typed at your desk top !!!:D
 
If the idea was to make it safer for some equipment somewhere then I'm sure that the POCO are now going to start pulling in seperate neutals on the poles and service drops and laterals. I'm sure that I have seen more open neutrals on services than a mwbc. I"ll think I'll suggest that to Duke Energy this morning:cool:

Another aspect of this that is going to be interesting is in the design,installation aspect,how long before the design pros can convert to the new way. We have completed one job using the 2008 NEC and I can say that trying to get all the circuits all stacked together was certainly a challenge. after that job I can now understand why the CMPs now allow more than a 42 space panel, juggling ABC, BCA,CBA takes some thinking along with the single phase loads intermixed.
 
iwire said:
This new rule will result in more live work being done. I have no doubt of that at all.



That is exactly right and will result in electricians deciding to work it hot where before they could easily shut off one leg.
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That's a point I had not considered. Interesting.

...and an electrician employed by a company which has a hot work policy in place, and who follows a hot work matrix is either faced with a choice of following the policy or working hot in order not to inconvience the customer at the risk of his own safety.

Bob, from a design standpoint will you continue to install multiwire branch circuits?

The disconnection of all poles is one thing, but the identification of those circuits as described in 210.4 (D) a.k.a. grouping, was a practice that I was taught how to do from the beginning. That practice, if followed, allows the electrician to identify multiwires, and then determine if all the legs need to be shut off. That works if only qualified individuals are the only ones ever to work on these circuits. But we know that's not going to be the case.

The simultaneus rule seems to be to protect the unqualified.
 
I think three things will happen:

a) three-pole breakers will not be installed because of cost of internal trips
b) approved handle-ties will be used to pass inspections
c) those handle ties will be popped off the first time someone comes back to do maintenience, weather it be electrician or handyman.
 
jerm said:
I think three things will happen:

a) three-pole breakers will not be installed because of cost of internal trips
b) approved handle-ties will be used to pass inspections
c) those handle ties will be popped off the first time someone comes back to do maintenience, weather it be electrician or handyman.
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And I agree with you on all points.

Roger
 
jerm said:
I think three things will happen:

a) three-pole breakers will not be installed because of cost of internal trips
b) approved handle-ties will be used to pass inspections
c) those handle ties will be popped off the first time someone comes back to do maintenience, weather it be electrician or handyman.
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Yep, end of story.
Good or bad, either way it's a "pass the inspection" rule only, which is stupid.
If they really want it done, they need to require multipole breakers only. . And even then some will get switched to singles after inspection.
 
iwire said:
Larry, you have enough knowledge to be able to work on one part of a MWBC without smoking other parts. Only qualified people should be digging that far into an electrical system. I think the new rule stinks.
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Hear Hear!

It should make for some interesting service calls though. "Why are ALL the lights out? If all you are changing is the one switch?"
 
brother said:
What i have also seen is some electricians will just take the wire off of that 'pole' of the breaker they are working on so now that circuit is not hot. That way the other 2 circuits stay on. This is if its a 3 pole breaker.
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That is another way around it that trade people will use and I say more power to them.

Roger
 
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