Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

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Please PING one of our electrically smarter guys!

Posted by bartc (A) on June 3, 2007 at 06:35:58

In Reply to: Two questions, then posted by remi on June 2, 2007 at 19:35:53:

I can try to answer from my limited knowledge, but it's really limited!

BX has only 2 wires. Common in housing after WWII. But that does NOT mean it isn't grounded, it is! It's grounded by using a metal box in the wall that is connected by flexible metal conduit in the wall all the way to the grounding system in the main electrical box to your house. The backstrap of the outlet duplex is connected to that circuit by the metal screws that hold it to the wall box in your room, so the entire system IS grounded in that kind of configuration. That's what I have in my house. You don't see 3 wires for a reason, but it's still grounded.

Of course, I have no way of knowing if your house is wired that way, but I'm guessing it might be. You can verify that with your local building permit office, since they will know from the original permit in the 1950s. Or you can have an electrically sophisticated guy tell you more or actually look into your wall box and determine it. It's a good idea to do one or the other.

Meantime, I'm told (and here's where my electrical theory and knowledge falters) that 2 prong appliances are "internally grounded" in some way. I have no idea what that actually means or whether it's as safe as earth grounding that 3 prong stuff uses. Consult one of our experts here.

I have no idea what your LED is telling you and won't even hazard a guess. Do you see the emphasis on HAZARD?

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Kimber Kable

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