Buildup on DC breaker

Hill_Country

I have three MidNite Solar MNEPV DC breakers (two 12 amp and one 10 amp) that have some corrosion/buildup on the breaker where the 10 AWG copper stranded wire (THHN/THWN) connects to the breaker itself on the top (these breakers have wire connection points on both the top and bottom). It is a white-ish/grey-ish powdery buildup. The three DC breakers are housed in a small MidNite Solar Big Baby Box. The box is located in a covered carport that is protected from the rain, but is not in a conditioned space. See (http://www.midnitesolar.com/productPhoto.php?product_ID=183&productCatName=Breakers&productCat_ID=16&sortOrder=18&act=p) for the DC breaker I'm using.

It was recommended to me to use Noalox (anti-oxidation compound) or a similar compound to prevent this from happening. Has anyone ever experienced this before or been in this situation? If so, what is the best practice for applying Noalox (or any anti-oxidation compound) to this setup...do you apply it only to the bare end of the copper wire and then insert into the breaker? Or do you dab a bit of Noalox on the clamp of the breaker itself and then insert the wire after that? I don't want to ruin/compromise the breaker by using the anti-oxidation compound...

Dave Angelini

If the wire was new or shiny clean when you installed the new breaker, this should not of happened unless you live on a boat or at the sea shore. If this was not the case, you should clean the wire and the inside contact area of the breaker with a fine metal brush and rinse lightly with good vodka. I would not use NOALOX.

BB.

I have seen (and had) water follow wire/conduit to the breaker panel and corrode the wiring+connections.

Besides salt air/humidity issues (cold panel next to a sink/shower/washer/unvented drier/other source of humidity)--Is there some other source of chemical/gasses?

-Bill

Hill_Country

The 10 AWG stranded copper wire and DC breaker were brand new when I installed them in February of 2015. Our AGM battery bank (battery bank = 8 6v sealed AGM Concorde SunXtender batteries) is located within 5 feet of the breakers, but they should not be causing this corrosion. The breakers are located inside a MidNite Solar Big Baby box in a carport near a breeze-way, so I doubt there is any buildup of gas; plus the fact that AGMs of this type should not be significantly off-gassing, if at all. Perhaps the fact that the wind can blow through by the carport may be to blame in this case. Like I mentioned, the box doesn't get directly/indirectly rained on per se, but I could see moisture being the issue here during humid days or during heavy storms that may have blowing moisture.

What is the reason you should NOT use Noalox in a situation like this? I had contacted MidNite Solar and they are the ones that recommended I use some sort of anti-oxidizing compound to address the corrosion.

What sort of solution would you recommend to keep this corrosion from occurring?

I'm just not sure how to proceed here...

BB.

Using some sort of NOALOX is fine... But remember that if you have problems with moisture/etc. getting into the box, it can cause corrosion elsewhere--Such as inside the breakers themselves.

For boxes installed outside/where weather can get to them, having all of the conduit/wiring enter from the bottom of the box (not from top/sides) can help reduce the chances of water getting into the box.

I had a service drop that brought a little water from the roof flashing down to the top of my breaker box. 20+ years later, I had to replace the service because water slowly worked its way in and corroded wire connections/breaker bus connections/etc.

-Bill

Dave Angelini

I do not use noalox because of what Bill said and I did not have time to go into. Find the cause of the moisture problem and correct it. You may need a better enclosure rated for moisture or ?
You never said if the contact between the wire and the breaker clamp showed corrosion? If there was corrosion in the contact area that is really pretty bad !

Hill_Country

Thanks for the responses! I will have to take some photos, but the corrosion is only on the breaker's top 'clamp' area near the top of the breaker. The buildup seems to accumulate on the tiny horizontal flat surface where the compression clamp squeezes against the wire. To be clear, the buildup is not in the vertical contact area (i.e. contact area = where the bare copper wire is physically touching the breaker's connection and held in place through compression).

Vic

Hi Hill..,

The one important thing about the BigBaby box, and the other MidNite boxes that have similar construction, it the it IS NOT rated for outdoor use. It is an Indoor box ... " Environmental Rating - Type 1 (Indoor) ":

http://www.midnitesolar.com/productP...tCatName=Small Breaker Boxes&productCat_ID=10&sortOrder=2&act=p

You really would want a 3R type enclosure, IMO, and anything that you do to try to alleviate even condensation making the components inside the box - wet -, will not cure the fact that water is, and will continue to find its way inside, which can damage the breakers or render them ineffective at the job that they are there to do.

Combiners are rated for outdoor use.

FWIW, Vic

Vic

Hi again Hill..,

MidNite has a clearance deal on a small MNPV3, three DIN Rail breaker Combiner, which might do the trick for your application:
http://midnitesolar.com/Forum/index.php?topic=2335.0

Hope that this is OK, Good Luck, Vic

engy-rest

And what about it - I think it should also done the job.

http://www.solar-electric.com/mnpv3.html