Rusty BX

[GerryB]

I looked at a job today, a two fam that needs a lot of rewiring, wondering about if I can keep any of the old bx. It is rusty in spots but not all the way through. The house was vacant quite a while. I was thinking maybe I could spray something on it and see it it perks up. Any ideas?

 

[GoldDigger]

....I was thinking maybe I could spray something on it and see it it perks up. Any ideas?

I can pretty much guarantee that it will never bloom again.

More seriously, are you wondering whether it is safe to leave it in place, with or without a coat of oil or rust inhibitor? For the first question I would ask whether you can identify why it rusted and whether it is likely to continue to rust.
Anything that you spray on it will be essentially cosmetic and might also damage the insulation of the wire inside if that is not oil and chemical resistant.

What is the EGC situation? I would not expect the jacket of the old BX to be usable as an EGC, so if there is no wire EGC and you need to have one I would say to remove the old BX and recycle it.

 

[ActionDave]

I've seen lots of BX that had a patina of rust on it that is fine to leave alone. If it's corroded that's another matter and I would remove it.

 

[GerryB]

Thanks for the replies. I had to go to my dictionary for "patina 1. A thin layer of corrosion, usually brown or green, that appears on copper or copper alloys, such as bronze, as a result of natural or artificial oxidation." This stuff has some brown rust and some whitish on it, which I've seen before. If I get the job I'll check them further for "patina or full corroda" Only about 10 of them if they need changing.

 

[gadfly56]

You could try Sprayon's WL740 cold galvanizing spray. It has very low VOC's and is very unlikely to damage conductor insulation.