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Old 11-15-2008, 03:48 PM   #31
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Conduit Fill and Derating


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I have seen double pole arc fault and gfci breakers, so yes, they are.

Depends on the circuit. If the conduit goes to a bedroom for instance, yes you need afci protection.

MWBC will not work with single pole afcis, but your not allowed to use single poles with MWBC, only common trip dble poles.

Its good you don't have a square d panel there...their breakers are SO expensive...
HI;

Can you joint together together 2 AFCI or GFCI breakers in a CH panel to create a double pole or doesn't it work that way at all?

The 15 and 20A breakers are around $6 for both the QO and CH panels. However I just looked it up and your right many of the larger CH breakers are cheaper. All of the breakers are MUCH more expensive than the breakers for the panels like the home line. But I really wanted a nice panel with a full copper bus bar. I just looked it up and the CH double pole shared neutral AFCI breakers are about $135 (from the prices I saw online), a bit on the pricey side.

Jamie
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Old 11-15-2008, 03:50 PM   #32
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Conduit Fill and Derating


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HI;

Can you joint together together 2 AFCI or GFCI breakers in a CH panel to create a double pole or doesn't it work that way at all?

The 15 and 20A breakers are around $6 for both the QO and CH panels. However I just looked it up and your right many of the larger CH breakers are cheaper. All of the breakers are MUCH more expensive than the breakers for the panels like the home line. But I really wanted a nice panel with a full copper bus bar. I just looked it up and the CH double pole shared neutral AFCI breakers are about $135 (from the prices I saw online), a bit on the pricey side.

Jamie
If your not installing new circuits, I wouldn't even install afci breakers.
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Old 11-15-2008, 04:59 PM   #33
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If your not installing new circuits, I wouldn't even install afci breakers.
These are old circuits I am hooking up right now, I can't afford to do the AFCI's now. But was planing on try to replace the breakers with AFCI in the future as I could afford to.

Do you think the AFCI's are not worth it? If you have nice solid high quality wiring and outlets and switches in place, do the AFCI's really provide any benefit?
Thank You.
Jamie
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Old 11-15-2008, 06:20 PM   #34
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These are old circuits I am hooking up right now, I can't afford to do the AFCI's now. But was planing on try to replace the breakers with AFCI in the future as I could afford to.

Do you think the AFCI's are not worth it? If you have nice solid high quality wiring and outlets and switches in place, do the AFCI's really provide any benefit?
Thank You.
Jamie

I'm an electrician with a house built in the 70's and I still dont see a need for them, I have my reasons, for one, not enough testing was done before they were entered into the almighty code book, so I just dont see enough proof that they do anything. except that they will locate shoddy wiring practices. ( shared circuit neutrals, ground to neutral connections.)
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Old 11-15-2008, 06:30 PM   #35
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I'm an electrician with a house built in the 70's and I still dont see a need for them, I have my reasons, for one, not enough testing was done before they were entered into the almighty code book, so I just dont see enough proof that they do anything. except that they will locate shoddy wiring practices. ( shared circuit neutrals, ground to neutral connections.)
I am rewiring several parts of my house and replacing every outlet. So I will discover and bad wiring. ( I have found some weird combinations put onto a circuit, all origional wiring put in place in 63 when the house was build. For example: Kitchen lights, Microwave, foyer, closet, outside outlet, out side house lights, lamp post, all on one 15A ). In short, I will catch any wiring problems myself, if thats all the AFCI's are really good for, then I don't need to spend $1,000 to populate my box with expensive devices that tell me my wiring is good.

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Old 11-15-2008, 06:33 PM   #36
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Originally Posted by jamiedolan View Post
I am rewiring several parts of my house and replacing every outlet. So I will discover and bad wiring. ( I have found some weird combinations put onto a circuit, all origional wiring put in place in 63 when the house was build. For example: Kitchen lights, Microwave, foyer, closet, outside outlet, out side house lights, lamp post, all on one 15A ). In short, I will catch any wiring problems myself, if thats all the AFCI's are really good for, then I don't need to spend $1,000 to populate my box with expensive devices that tell me my wiring is good.

Thanks
Jamie

The problem is, once you re-wire, you need to bring everything up to current code. So for instance, if you add a receptacle in your bedroom, then it has to be AFCI protected, even if the rest of the room is not.
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Old 11-15-2008, 06:35 PM   #37
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( I have found some weird combinations put onto a circuit, all origional wiring put in place in 63 when the house was build. For example: Kitchen lights, Microwave, foyer, closet, outside outlet, out side house lights, lamp post, all on one 15A ). Jamie

That was the norm back then, they just didnt have large loads like they do today.
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Old 11-15-2008, 06:41 PM   #38
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The problem is, once you re-wire, you need to bring everything up to current code. So for instance, if you add a receptacle in your bedroom, then it has to be AFCI protected, even if the rest of the room is not.
I am on the 2005 code cycle here in wisconsin. So my understanding is that yes, an addition to a bed room would require an AFCI, but no where else would. I belive that this changes in 2008 to require virtually everything to be AFCI that isn't required to be GFCI.

Are they making AFCI outlet style units or only AFCI breakers?

Jamie
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Old 11-15-2008, 06:44 PM   #39
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I am on the 2005 code cycle here in wisconsin. So my understanding is that yes, an addition to a bed room would require an AFCI, but no where else would. I belive that this changes in 2008 to require virtually everything to be AFCI that isn't required to be GFCI.

Are they making AFCI outlet style units or only AFCI breakers?

Jamie

You are correct with the above statement, were on the 2005 as well, and thankfully skipping right over the 2008, and I've yet to hear about an afci receptacle style unit, but the NEC seems to believe they exist.
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Old 11-15-2008, 08:01 PM   #40
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Just regular double pole breakers that take up 2 slot positions - because you have to make sure each circuit draws power from each phase?
That's some of it. The code makers wanted to ensure that the neutral would not be overloaded, for one. The other reason is they wanted to ensure that if you are working on an MWBC that you can't open a neutral and be electrocuted by voltage from the other half.

Quote:
So they trip in common as well, correct? So a lighting circuit, and your outlet circuit on a branch with a shared neutral will both trip at once if the outlets cause a fault/overdraw, correct?

Jamie
Yes that would happen as well. I don't usually recommend that DIYr's mess around with multiwire circuits, because they can confound even seasoned professionals. But if the circuit terminates in a junction box near the panel, and you are careful, this can reduce your pipe and box fill. Since you are not on the 2008 Code, you don't have to necessarily put them on double poles. But you must be mindful that each leg lands on a different phase in the panel.

BTW, as far as AFCIs go, I believe they are a waste of money. In my little pocket of Alabama, where we have no enforcement of codes, I don't use them. I only use them in jurisdictions where they are required. In one instance, I followed behind a handyman that wired some rooms before he was fired. I placed his crap work on AFCIs, but other than that, they exist because of the manufacturers' reps on the code making panels, IMO.
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Old 11-15-2008, 09:17 PM   #41
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Wisconsin is on 2005.

Jamie

Yes it is still on 2005 code cycle until next spring { 2009 } we will take in 2008 Code cycle however there are few changes along the way myself and few Wisconsin sparkys and Inspectors just got the info not too long ago.

AFCI requirement still optional the mantory usesage is pushed back to 2011

TamperResenst receptales yes .,, go ahead with it

Removed GFCI extempts but sump pump receptale still have extempt unless local code stated else.

There are few other changes as well almost parallel with full 2008 code unchanged expect few words change along the way.

Merci, Marc
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Old 11-15-2008, 10:02 PM   #42
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That's some of it. The code makers wanted to ensure that the neutral would not be overloaded, for one. The other reason is they wanted to ensure that if you are working on an MWBC that you can't open a neutral and be electrocuted by voltage from the other half.
I went and got some double pole breakers, I'll need more breakers by the time I am done anyway.

Is there anything you need to do to make sure the neutral isn't over loaded? Are factors that apply? Or is it as simple as 2 circuits that land on different legs of the panel both share one neutral wire that is the same gage as the circuits? i.e. 2 -20A 12 gage hot circuits from 1 double pole breaker run from panel to destination. Both use the same #12 white ground wire. Is it that simple?

Thanks
Jamie
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Old 11-15-2008, 10:24 PM   #43
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I went and got some double pole breakers, I'll need more breakers by the time I am done anyway.

Is there anything you need to do to make sure the neutral isn't over loaded? Are factors that apply? Or is it as simple as 2 circuits that land on different legs of the panel both share one neutral wire that is the same gage as the circuits? i.e. 2 -20A 12 gage hot circuits from 1 double pole breaker run from panel to destination. Both use the same #12 white ground wire. Is it that simple?

Thanks
Jamie
On a properly installed MWBC, the neutral can carry no more current than any one leg. If you use a double pole breaker, you can't overload the neutral. If you use two different breakers, you must be sure to place the breakers on different phases.
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Old 11-15-2008, 11:10 PM   #44
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On a properly installed MWBC, the neutral can carry no more current than any one leg. If you use a double pole breaker, you can't overload the neutral. If you use two different breakers, you must be sure to place the breakers on different phases.
As long as they are on different phases in the panel, that ensures that the neutral can not be overloaded? I know that the neutral is a return path for electricity, but I don't know how much or what amount of power it exactly carries.

So if both of thoses 20A circuits ran with say a 18A load, the one 12 gage neutral would still be adequate protection?

Does that shared neutral pose any potential problems with GFCI devices? I read some things a while back that gave me the impression that a shared neutral could cause a problem with GFCI because the outlet senses load on the neutral from the other circuit and trips. Or did I understand this incorrectly?

Thanks again. I have to get my hook up finished tommorw. I had to take a break today, That was a ton of work yesterday to get that old panel cleared out and everything) but currently only have 4 circuits hard wired, and a couple of things jumped into a open box (yea not safe).

If the MWBC's will work for a couple of these, it will save me a lot of time, Ill be able to do all of the old circuits in 2 4x4" boxes up there in the joists and the rest of them can be done elsewhere like in the crawl space.

Thanks again
Jamie
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Old 11-15-2008, 11:12 PM   #45
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On a properly installed MWBC, the neutral can carry no more current than any one leg. If you use a double pole breaker, you can't overload the neutral. If you use two different breakers, you must be sure to place the breakers on different phases.
So does this in effect mean that 2 -20A circuits only really have the capicity for 20A total and not 20A each for a total of 40A? I am confused about how the double pole breaker ensures that the neutral is not overloaded.

I must be missing something.

Jamie
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