Arc fault wiring dilemma

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Old 08-02-08, 02:28 PM
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Arc fault wiring dilemma

OK I have a slight problem
When I went to install a 15amp arc fault circuit breaker in place of a regular circuit breaker, I noticed that 2 circuits were fed off of same wire. in other words, 14/3 cable was run into the box with the black to one 15 amp breaker and the red to another 15amp breaker with a common white to the neutral. I understand that the arc fault should not have a shared neutral. It also says in the directions that the breaker should not be used on cable which has more than 3 connectors PLUS ground. Since this circuit is fed by 14/3, does this mean that I cannot use this breaker? I don't know how to get around this problem and I want to do this right (if possible with the arc fault) while NOT cutting any corners....any help will be duly appreciated!

Thanks
Ben
 
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Old 08-02-08, 03:03 PM
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Originally Posted by italian_guy View Post
OK I have a slight problem
When I went to install a 15amp arc fault circuit breaker in place of a regular circuit breaker, I noticed that 2 circuits were fed off of same wire. in other words, 14/3 cable was run into the box with the black to one 15 amp breaker and the red to another 15amp breaker with a common white to the neutral. I understand that the arc fault should not have a shared neutral. It also says in the directions that the breaker should not be used on cable which has more than 3 connectors PLUS ground. Since this circuit is fed by 14/3, does this mean that I cannot use this breaker? I don't know how to get around this problem and I want to do this right (if possible with the arc fault) while NOT cutting any corners....any help will be duly appreciated!

Thanks
Ben

You will have to hold out until 2 pole arc fault breakers are on the market.
 
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Old 08-03-08, 01:36 AM
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Arc faults will not work with a shared neutral for 2 circuits. It will trip one circuit or the other every time. Arc faults are a relatively new product and requirement. I know that I have alot of houses out there with that 3 wire home run and can guaruntee that you will find this same wiring method in a great percentage of houses. Arc faults are very sensitive and yes you will have to wait until they solve that problem to be able to install it in this kind of setup.
 
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Old 08-03-08, 12:53 PM
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Right now I know there is one two pole AFCI breaker on market but I just can't comment on that one yet because I have not got that one yet but for GFCI yeah I did see it pretty often.

In few years I am sure the two pole AFCI breaker will get common once they slove the issue with tripping level as scubakirk describing.

Of course it pretty common pretty good percentage of homes do have " home runs " which it called MWBC { multiwire branch circuit } they are pretty good without much issue but however there is one golden rules with MWBC is anytime you work on the jucntion box make sure you turn off both breakers when you do any change on the connection.

If you don't follow the warning on that one what will happend that if you work on netural anytime you disconnected the netural the other circuit still be alive you will get hit from it and the other thing that if both circuits are on and some reason the netural get " lifted " { disconnected due bad connetion or came apart for some reason } anything on 120 v will get a " magic smoke " the voltage will jump up much as 240 volts depending on what it on that MWBC.

Merci,Marc
 
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Old 08-04-08, 10:16 AM
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If you happen to have an Eaton/Cutler-Hammer breaker box it is your lucky day, because they are the only manufacturer with a 2-pole AFCI breaker.

For type CH boxes: CH215AF
For type BR boxes: BR215AF

I do not believe that any of the other brands have a 2-pole AFCI on the market yet.
 
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Old 08-04-08, 10:24 AM
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Marc
Thanks for that info. Didn't even cross my mind about killing both breakers on a homerun circuit. Usually, I just kill the circuit that Im working on and not the other half that the shared? neutral is on. I have to admit though, I am a little confused about a neutral wire being "lifted". Are you saying that if one neutral becomes disconnected, you get 240 volts on a 120 volt circuit?
Finally, nah my breaker box is a GE....although...get this....a GE box with Siemans breakers in it...This work was done by an electrician over 6 yrs ago......I just found it yesterday when I pulled out one breaker to put in an arc fault and I saw "siemans" written on the breaker. When I did my subpanel and my welder wiring, I ONLY put in GE breakers.....the arc fault is a GE model too. (although I know Siemans has arc faults too...are these things interchangeable???
 
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Old 08-04-08, 10:46 AM
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Originally Posted by italian_guy View Post
Are you saying that if one neutral becomes disconnected, you get 240 volts on a 120 volt circuit?
Sort of. The voltage will divide unevenly between the two legs of the multi-wire circuit if the neutral becomes disconnected. For example you could have 160V and 80V, or some other combination to make 240V.

In terms of safety, the neutral has the potential to be energize when either of the two breakers is on. Switching off only one breakers leaves the chance of shock on the neutral.

For this and other reasons, the 2008 code now requires all new multi-wire circuits to use double-pole breakers so there is no chance of missing the second breaker when switching the circuit off.

I ONLY put in GE breakers.....the arc fault is a GE model too. (although I know Siemans has arc faults too...are these things interchangeable???
Some of them are listed for use in other manufacturers' panels. The spec sheet printed by the breaker manufacturer has a table in fine print which will list all of the allowed makes and models of breaker panels in which that breaker may be used.

I don't want to be too generalized, but most of the modern breakers and panels are safely interchangeable; the manufacturers have standardized a lot of the panel designs. Of course keeping with the same brand is the most reliable way of maintaining compatibility.
 
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Old 08-04-08, 10:47 AM
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I had a couple type BR breakers in my Siemens panel...

I switched them out with QP... Obviously they work but it didn't sit right with me. If I recall, they grabbed the buss a little loosely and would come out in your hand when you manually tripped them (if the cover was off).
 
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