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I'm trying install a lamp to my apartment but it didn't light up as I expected. I recently moved in and this is the first time I'm trying to install a lamp here. The spot where I'm trying to install the lamp is just a hole in the ceiling with three wires hanging out: Two brown (live?) and one blue (neutral?). Some Googling revealed to me that the separate live wires can be used to control specific bulbs in a multi-bulb lamp. Nearby there is a switch on the wall with two buttons which I assume is for these wires. So apparently the idea is that current flows from each live wire through the bulbs to the common neutral wire when to buttons are toggled on. One live wire and the neutral were connected in parallel to a connection strip, while the other live wire was connected alone to its own connection strip.

My lamp has a spring-powered connection strip with L and N labeled holes so I simply took one of the brown wires to L and the blue wire to N.

I removed the connection strips and tried to measure the voltage to see if the problem was somewhere else in the circuit, and I noticed that each of the live wires measures around 50-54 volts with respect to the neutral, even though the AC line voltage in my country is 240 volts. Even stranger, I measured this voltage regardless of the positions of the switch buttons! Only when I removed the fuse I got 0 volts.

So I assume the reason why the lamp didn't light up was that the voltage was way too low. Could somebody point what is it that I'm doing wrong, or is there something wrong with the wiring on my apartment?

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marked as duplicate by RedGrittyBrick, ThreePhaseEel, Ed Beal, mmathis, Daniel Griscom Mar 4 '18 at 13:01

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migrated from electronics.stackexchange.com Feb 26 '18 at 20:40

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    the 50V reading is because you are measuring a length of unconnected wire with a voltmeter that has a high input impedance ... the wire acts as an antenna and picks up the voltage from nearby cabling. .... even though there is a voltage, there is almost no available current. ... connect the wire to a light bulb and measure again. ... you will most likely read 0V – jsotola Feb 26 '18 at 20:53
  • "One live wire and the neutral were connected in parallel" - one of those isn't what you say they are if it doesn't immediately pop the fuse, or I'm misunderstanding what you mean by connected. You mean punched down into the same block that has multiple separate contacts? (I'm from the US; we don't have those in our boxes...) – Mazura Feb 26 '18 at 23:32
  • @Mazura I mean parallel in the sense that they are connected next to each other, separately into a connection strip, not as in shorted together. – S. Rotos Feb 27 '18 at 20:16
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I do agree with jsotola , inductive coupling created a voltage on this wire. When next to a live line for a distance. Lines of force from the hot AC line induce a voltage if the lines ran further together the voltage would be higher (this is how transformers work) , it is commonly called phantom voltage as there is really no potential. Did you try and measure the voltage with the switch on? Also verify the breaker since this is all new to you someone may have turned this breaker off.

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  • "Only when I removed the fuse I got 0 volts." - so, the fuse is good then I'd guess. Then why no power? – Mazura Feb 26 '18 at 23:31
  • I did measure the voltage with the switch on too, I got the same result. – S. Rotos Feb 27 '18 at 20:13

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