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I am looking for some advice on troubleshooting an electrical circuit in my 1920s home. I apologize for the length of this post, but wanted to give as much detail as possible. The circuit feeding most of the house is all BX through the walls with exposed conduit in the basement. When we moved in, all of the electrical outlets were changed from two-prong to three-prong plugs, but none were tested afterwards. We bought a TV recently that shorted through the CATV cable ground when we plugged in the TV. Thinking this was pretty odd (since the old TV had been just find connected in the same way), I tested the AC receptacle - reverse polarity. I then tested the other receptacles on the circuit and nearly all were reversed but all are connected "correctly" with the white on neutral and black on hot.
Then I started looking inside the boxes of each device and tracing the circuit. What I found was that the first device (a receptacle) is definitely wired correctly and checks out fine when tested. The B/W then run up the wall to (I believe) a light fixture. From there it gets a little confusing. The light appears to be switched on the neutral (white), with the incoming whited tied to a white leg which is connected to the switch. A separate red takes the hot (black) from the light to the switch. This pattern continues in many places - in each box whites are tied directly to whites, blacks are tied to the device and a red wire, with the return leg from each switch coming on black as well. In all a bit more than a dozen devices are tied into this circuit. Most of the electrical will be replaced and remapped (ie, separate circuits for the bathroom, office, bedrooms, etc.) in the coming years as we renovate, so for certain areas I would be okay with a second-rate fix, but normally I like to find the root and fix it there.
Even though the neutrals are switched, I don't see why the receptacles are reading as reversed, since the circuits seem to be connected correctly. What am I missing? Here is what I *think* is a portion of this circuit in the diagram (View image: circuit.jpg). So, my questions are:
1) what is the most reliable way to isolate the cause of the reversed polarity, and
2) what is the most efficient way to fix it in the short term? If needed, would I likely be able to disconnect the BX at the fixture and pull through the wall, also using it to help fish the replacement romex?
I am comfortable doing the work myself and have the skills to troubleshoot (I'm an EE), but would love some practical advice on troubleshooting this problem. As usual with our house: something simple like a new TV leads to something major like electrical replacement. Thanks in advance for any help!
Then I started looking inside the boxes of each device and tracing the circuit. What I found was that the first device (a receptacle) is definitely wired correctly and checks out fine when tested. The B/W then run up the wall to (I believe) a light fixture. From there it gets a little confusing. The light appears to be switched on the neutral (white), with the incoming whited tied to a white leg which is connected to the switch. A separate red takes the hot (black) from the light to the switch. This pattern continues in many places - in each box whites are tied directly to whites, blacks are tied to the device and a red wire, with the return leg from each switch coming on black as well. In all a bit more than a dozen devices are tied into this circuit. Most of the electrical will be replaced and remapped (ie, separate circuits for the bathroom, office, bedrooms, etc.) in the coming years as we renovate, so for certain areas I would be okay with a second-rate fix, but normally I like to find the root and fix it there.
Even though the neutrals are switched, I don't see why the receptacles are reading as reversed, since the circuits seem to be connected correctly. What am I missing? Here is what I *think* is a portion of this circuit in the diagram (View image: circuit.jpg). So, my questions are:
1) what is the most reliable way to isolate the cause of the reversed polarity, and
2) what is the most efficient way to fix it in the short term? If needed, would I likely be able to disconnect the BX at the fixture and pull through the wall, also using it to help fish the replacement romex?
I am comfortable doing the work myself and have the skills to troubleshoot (I'm an EE), but would love some practical advice on troubleshooting this problem. As usual with our house: something simple like a new TV leads to something major like electrical replacement. Thanks in advance for any help!
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