Installing a new ceiling light fixture...help please.

[designer33]

Good Morning,

I just bought a new ceiling light and am trying to install it in existing mounting box.

There are five wires coming out of the ceiling, two greens that are twisted together, two whites that are twisted together and a single yellow. i have a voltage tester and it seems that the two greens seem to be the hot wires, since they make the tester glow the brightest while the two white only show a slight dim and the single yellow only a slight dim.

i connected the black in the light to the green (hot) wires that are twisted together and the white in the light to the white wires twisted together and grounded the light with the bare copper wire. the yellow wire was left unhooked.

when i swich the power back on the light fixture comes on but when i hit the wall switch to off (down) the fuse blows and trips the circuit.

i need to know why there are two hot wires and two white wires, and what the yellow could be. also should i untwist the pairs of wire and test these separately?

thanks for any help, i'll be monitoring this thread until about 3 cst. thanks.

[pcboss]

How was the old fixture wired before? The new one should be wired the same.

Green wires should never be the hot wires. Green wires are reserved for grounding.

Try switching the fixture black to the ceiling yellow. The bare or green from the fixture should attach to the ceiling greens.