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I removed our ceiling light today and the house wiring had no distinction between the two wires connecting to our light. The light fixture's wire had the same color insulation, but inside, one of the wires had red metal/copper and the other had silver metal. I assumed that the silver metal wire was therefore connected to the neutral house wire and so assumed the house wire on the right was neutral. Again, the house wires were identical, AFAIK.

Then, our new light had two similar wires as well, although the insulation on one of them had white writing, which I assumed should be connected to the neutral house wire.

Questions: 1) Am I correct in what I assumed and did? 2) I have a cheap multimeter with red and black leads. Can I use this on the live circuit to confirm which is which? I tried using my multimeter in an outlet, and both ways I tested the two-pronged outlet (red on left, black on right and vice-versa) gave me the same 120v reading - neither flipped the direction of the meter, so hopefully there is another way to do this. My meter looks like this: https://goo.gl/images/9eF4KP

old light attached to wires.  zooming in, you can see the silver wire attached to the right and the copper /red metal wire attached to the right.

house wires with no way for me to identify

new fixture I installed, assuming the black wire with white letters is neutral

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    I'll leave the real answer about how to correctly wire the light to the experts. But as far as the multimeter: There is NO DIFFERENCE when measuring AC between hot to neutral and neutral to hot. The meter simply can't tell the difference, because there is no difference. However, if you check "hot or neutral" to ground then if you picked neutral you should see 0V (or very low - neutral and ground are bonded together at one location (typically the main panel)) and if you picked hot then you should see 120V. (Except you might trip a GFCI along the way). – manassehkatz-Reinstate Monica Aug 2 '18 at 5:09
  • Can the electrical tape be removed to see the insulation underneath? – The Evil Greebo Aug 2 '18 at 13:08
  • Yes, although I sealed it back already so I will leave it alone and assume that the silver wire was correctly wired and I am OK. – Damian P Aug 4 '18 at 5:07
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The fixture is supposed to be wired so that the hot from the house goes to a particular point on the fixture. In the case of screw base the central contact is supposed to be hot and the thread contacts neutral.

The lamp cord has one side marked (ribbed in your case) to distinguish the two conductors. See Which side of a two-wire cable should be used for "hot"?

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Your assumptions on wire color is correct. On the cords with silver / copper the silver is the neutral and that goes to the shell of the lamp holder the copper goes to the center. How to tell which wire is hot in the box, use your meter connect 1 wire to the meter then touch the other lead to a sink or faucet, a metal cook top or oven, one of the 2 wires will show voltage that is the hot.

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