Electrical Wiring in the Home/Ghost or Phantom Voltage?

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Question
I live in a 3 unit 100yr house and needed to change a light fixture in a bedroom.  I turned off all circuits in my panel and still found the non contact voltage tester lighted and sounded at the fixture's box and wires (both neutrals and hots -- there are 5 pairs, one pair is cloth).  An electrical outlet in the same room had the tester light up and sound as well, so I plugged in my multimeter (fluke 113) in the neutral and hot -- but get no reading, my fluke says OL and when I go through the ranges manually, it's all 0 readings.  I thought I should be getting some kind of voltage reading.  What else can I try to get a reading?  Also, what other tests can I be performing to understand what is going on?

Answer
Thomas,

The voltage sensor type testers can and do give false readings from time to time. If your multi tester is telling you there is no voltage present then there most likely isn't. These wires may be having a voltage induced in them some where and its enough that the voltage sensor is picking it up giving it the appearence there is power. If its a Fluke voltage sensor like the one I have it will light up when it gets to with in about 2 inches of a live wire. In your case you probably  have to get the tip of the tester right next to the wire in order for it to light. This is how I can tell the difference between a wire that actually has power on it VS one that has a voltage induced in it from another wire. Just where this is taking place in the wiring of the house is a good question. It could be a conduit or a junction box.

Being this is a multi family and an older home that was probably turned into a multi family over the years where they had to separate the wiring from one apt to another you could very well have wires from one apt passing anothers in a common junction box or raceway where this phenomena can occur.

Bob
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Electrical Wiring in the Home

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PASCACK VALLEY ELECTRIC Bob Mossman

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Licensed Master Electrician (32 years) 6165B Contractor in Closter New Jersey with 40 years total experience in Residential - Commercial - Industrial work. Emergency Service - General trouble shooting and repair work - ONAN & GENERAC generator installation - Paddle fans - Kitchen & Bath exhaust fans - AC lines - Smoke detectors - Telephone lines - Cable TV lines - Computer network cabling - Exterior lighting - Recessed lighting - Security lighting - (200 - 150 - 100 amp service up grades) - Electric Heat - New circuits - New appliance hook ups - and more ! FREE ESTIMATES 201-358-1552 Fully Insured

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Licensed contractor in Closter New Jersey.

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"The Frank Williams School of Electrical Construction". My dear old boss is 100 ! and still going God Bless him. I started working for "Tenafly Electric" right out of high school at 19. He was tough but I learned more working for him in 8 and half years than most guys. We did mostly industrial work while doing some commercial and residential so I was fortunate to be exposed to all 3 areas of electrical construction. The guys I worked with were all good guys and I stay in touch with some of them still. Most of us went into our own buisness's which says something about the caliber of the guys I worked with. We had some interesting clients : Wella Corp. of shampoo fame, Farah Fawcett etc, I didn't buy shampoo for 10 years. It was a great place to work. Pan Am the former airline just before they went under, another great place to work, nice clean environment. C&C Metals, the largest button manufacturer in the US at that time, a not so clean environment but a very interesting place to work, lots of machine's cranking out buttons of all kinds but you had to be on your toes, it was a potentially dangerous place to be . All kinds of action going on around you.

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