AFCI with a Subpanel

15885 Views 10 Replies 6 Participants Last post by rjniles, Jun 23, 2011

Underdog

Discussion Starter · Jun 23, 2011 (Edited)

I am upgrading my subpanel (I've got a few older posts with the details) and I was quite shocked with the price of AFCI breakers. I am trying to figure out ways to cut costs but still keep everything to code and, more importantly, safe.

I saw a 60-amp two pole AFCI breaker on Amazon for $100. Could I put that breaker in the slot on my main panel that will feed the subpanel? Will that AFCI breaker then ensure AFCI compliance on the entire subpanel?

If so, are there any downsides to this?

EDIT -

I looked at Amazon again and it was a GFCI breaker, bah! Do they make 60 amp two pole AFCI breakers? Every time I search for them online, it brings up GFCI breakers.

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DangerMouse

· #2 · Jun 23, 2011

I agree, it's a nightmare for DIYers trying to comply with code since they introduced these. The prices about killed us!
I couldn't believe how expensive the REQUIRED breakers were....

If they make one, (AFCI 60a double) I should THINK the way you propose would cover the requirement. Of course, I could be wrong too.

DM

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gregzoll

· #3 · Jun 23, 2011

How are you going to figure which breaker in the sub caused the fault on the AFCI that is in the main?

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DangerMouse

· #4 · Jun 23, 2011

gregzoll said:
How are you going to figure which breaker in the sub caused the fault on the AFCI that is in the main?

And there's the downside! :laughing:

Thanks gregzoll

DM

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Underdog

Discussion Starter · #5 · Jun 23, 2011 (Edited)

gregzoll said:
How are you going to figure which breaker in the sub caused the fault on the AFCI that is in the main?

Yes, that is a downside.

BUT, how likely is it that I will actually have an arc that triggers the AFCI? Let's say (and please don't think I am arguing or being a smarta$$, I'm just trying to work out the economic decision out loud) that the 60-amp two pole AFCI trips. Would it be more likely that it tripped because the breaker was bad or I actually had an arc in the wiring?

So, the real question is: do I want to invest a lot of money up-front on multiple AFCI's so that I can determine which circuit had a fault at some unknown time in the future (maybe never). And in turn have a higher risk of one of the multiple AFCI breakers going bad (simply because there are more of them). Or, do I go the cheaper route (but just as safe) on the chance that I may never need to trace an arc fault?

Of course, this is all predicated on the idea that I can even find a 60-amp two pole AFCI breaker.

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brric

· #6 · Jun 23, 2011

Why is it that you think you need AFCI's in the first place?

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Underdog

Discussion Starter · #7 · Jun 23, 2011

brric said:
Why is it that you think you need AFCI's in the first place?

That's a good question. I assumed that I needed them because I am upgrading my old subpanel to a new subpanel. And I thought AFCI was now a requirement.

The inspector didn't tell me that I needed them (we haven't gotten that far on inspections yet) but I just assumed I did. Is the code clear on what triggers the need for installing AFCI breakers?

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rjniles

· #8 · Jun 23, 2011

brric said:
Why is it that you think you need AFCI's in the first place?

That was my thought when I first read this post. If the installation was code compliant when it was installed it does not have to be changed because the code changed unless you are making changes in a specific circuit that requires AFCI under the current code. And then you only have to bring that circuit into compliance.

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Underdog

Discussion Starter · #9 · Jun 23, 2011 (Edited)

Awesome! I'd love it if I only had to use an AFCI on the circuit that I am adding. Here is what I'm doing, let me know if you think it would trigger an AFCI for all of the subpanel circuits, or not.

I am moving the location of an existing subpanel to a new wall (I am installing brand new hardware as opposed to just moving the old hardware though). To move the subpanel location, I need to run new homerun wires to the first junction boxes on each circuit. Besides that, I am not changing any existing circuit.

I will be adding one new circuit for a new bedroom but I do plan on using an AFCI breaker for that new room.

Here is a link to my other post on this topic. It has a picture of my old subpanel.

http://www.diychatroom.com/f18/moving-subpanel-86926/

So, am I code compliant by only using an AFCI breaker for the new room and then having all of the old circuits on regular breakers?

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jbfan

· #10 · Jun 23, 2011

That is something only your local inspector can tell you.
Where I'm at, only new circuits would be required to have an arc fault, however, you are moving a panel and that my trigger more changes.

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rjniles

· #11 · Jun 23, 2011

You are doing a lot more than I imagined when I made my previous post. New sub-panel, new feeders from main (#), new home runs to all existing circuits (##).

# I doubt that the feeder for that fused sub panel is 4 wire and it will need to be when you install the replacement sub.

## I assume that the existing circuits you will be re-feeding are grounded based on age of fused sub panel. You may have to rewire them completely or add GFCI in the first receptacle and feed the down stream off the load side.

I am sure one of the Sparkys on here will give a better answer.

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