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Old 04-06-2014, 01:46 PM   #1
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Cu-Al Circuit breakers

Hi to everyone. I am in the midst of replacing my circuit breaker panel as it is original and rusty and corroded. As I was taking some pictures of it so I would rewire it correctly, I noticed that the breakers have Cu-Al written on them.
Can I replace them with "regular" circuit breakers or do I need to stick with the Cu-Al type? They are GE and are thin in their width, THQP type I beleive. I went to a box store yesterday and the electrician there said to stick with the Cu-Al type.
In doing a little research it appears that the Cu-Al is a "rating", and meant to be used with aluminum wiring. Are the 1969 Airstreams wired with aluminum wiring or copper clad, aluminum wiring? I am a little confused and want to keep the trailer safe.
Everyones help is greatly appreciated.


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Old 04-06-2014, 02:21 PM   #2
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Cu-Al refers to copper-aluminum so the breakers are rated for either type of wire. However, because of galvanic action, never put copper and aluminum wire together under the same screws as one will dissolve the other.

One usually has to increase aluminum wire size by one size to carry the same current as copper. For a 20 amp circuit, one would use #12 copper wire or would use #10 aluminum wire.

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Old 04-07-2014, 09:36 PM   #3
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Originally Posted by 69SlvrBelle View Post
Hi to everyone. I am in the midst of replacing my circuit breaker panel as it is original and rusty and corroded. As I was taking some pictures of it so I would rewire it correctly, I noticed that the breakers have Cu-Al written on them.
Can I replace them with "regular" circuit breakers or do I need to stick with the Cu-Al type?
It depends on whether you have aluminum wire. I believe that some trailers, but not all, made in 1969 used aluminum wire.

The advice on dealing with aluminum wire is controversial with the most conservative approach being to pull it all out and replace it with copper.

Other approaches are complicated to assess for safety. Part of the problem is that several alloys were in use, with some being more prone to causing fires from high-resistance terminations than others. Part of the problem is that CO-ALR rated devices haven't been manufactured for years and there is concern that old stock ones may have had the antioxidant coating deteriorate due to age.

One recommendation is to use one of two approved copper-to-aluminum connector blocks to retrofit a copper pigtail. They are expensive and difficult to get with one system only being available to licensed electricians who have gone through special training from the manufacturer of the connectors.
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Old 04-10-2014, 05:07 PM   #4
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I have been given to understand that the problem with aluminum is that it doesn't spring back after being stressed like copper does.

So, an aluminum wire under a screw gets hot and expands, and it squishes out as it does so. But it doesn't come back to the original shape, so now it's a little bit loose under the screw. So, the same thing happens next time, only more so.

I believe (note all the weasel words here) that a Cu/Al rated device will maintain a constant pressure on the conductor even it it changes size a little bit.

The best answer, however, is to use only copper wire.
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Old 04-10-2014, 08:50 PM   #5
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The Cu-Al designation means the breaker can be used with either copper or aluminum wire.

The issue with aluminum wiring is the potential for heat build up in connections due to increased resistance caused by oxidation. This causes the aluminum wire to expand then contract, thereby loosening the connection which can lead to meltdown, or worse. The key to successful service with aluminum wire falls into three categories.

1) Use connectors, switches, receptacles, breakers, etc. rated for aluminum service.

2) When joining copper to aluminum wire use a Cu-Al split bolt or equivalent.

3) Always use an oxide inhibitor on all aluminum connections. Oxygen is your enemy.

BTW many homes with copper wiring still have aluminum feeds to the kitchen range and HVAC systems.

I do not know when Airstream used aluminum wire, but if my rig had it I would not rip out interior skins to replace it. If I was doing a full blown restoration and had access to accommodate a change then yes I would make swap. Otherwise I'd inspect and replace compromised connectors, No-Ox them and keep on enjoying my rig.



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