One light with a switch loop

Hi Joed. I found this thread wile doing a search for this same issue.

I have one light with a switch loop. I have it wired just as you mentioned.
Power black connected via wire nut (in the light box) to switch white (white is marked with black tape on both ends)
Switch black to the neg at the light fixture.
Power white to the light fixture.
Light switch is off, I can see the word off on the switch. Flipped the breaker back on and immediately popped.
I was using a old ceramic fixture and replaced it with a new one.. it was cheap so what the heck. I have ohmed the switch and it functions correctly.

 

Welcome to the forums.

That thread was 20 years old. Always best to start your own.

A switch loop is a very basic. Hard to tell what you've done wrong.

 

I have things wired just like the diagram you posted. Breaker was off for safety when I installed it. Switch off verified buy Ohm meter and visual word off.
Flipped the breaker on a POP. Never got the turn the switch on.
Fixture is new. Power is fed from an outlet, in which white to white and black to black connections were made. Metered and got the correct voltage at the fixture before wiring the loop.

 

Then you need to open the splices and check with a meter to see where the short is.
Do you have old MC (BX) type wiring where the insulation is crumbling off ?

 

No.. all new 14/2.

at the outlet: (14/2) power in from the panel, 14/2 from the outlet box to the light and 14/2 carrying on to another outlet. All three whites wired nut and all three blacks wire but with pig tails to the outlet I tapped into. At the light fixture wired with switch loop just like the diagram.

 

You need to disconnect the feed to the new light circuit to verify the short is not there.
The circuit is basically a loop. Even wired wrong it won't create a short.

 

Yup. did that. Removed the light fixture, metered the power in and got correct voltage. Flipped the breaker and it did not pop. Verified the wiring was Power BLK to switch WHT and power WHT to fixture and switch BLK to fixture. I had an older ceramic fixture.. replaced with new. Connected and breaker popped.

Maybe it was tripped before I wired all that in. could be an outlet somewhere else that went bad.

 

If you had the switch off and it was wired correctly.... the light could not cause the short.

 

That is not correct. You are connecting the hot and neutral together causing a short.

Reidentify the white going down to the switch with black tape. Then connect that wire to your hot coming into the box. The black from the switch goes to the light. The whites in the ceiling box only get connected to the fixture.

 

His description is correct if you read it slowly.

 

I am still pretty sure something is wired incorrectly since the breaker trips immediately.

 

Are you sure it is a switch loop? How many wires/cables in the switch box?

 

In the outlet box I sourced power from all the whites and all the blacks are connected to get power. Three each and then the pigtail to the outlet. This outlet is the beginning of a run. Metered fine at 120 no breaker trip. The new power feed goes to the light box... just 14/2 ground, black, white. Then a run of 14/2 to the light switch. In the light box 4 wires, 2 black and two white then 2 grounds. Metered the power feed to the light box before any connections were made.. 120v no breaker trip.

The wiring in the box is power white to the fixture, power black connected to switch white, switch black to light fixture. The switch is a single pole switch only two wires that box, can't really mess that up. The breaker trips after these connections are made.

I'm beginning to think the breaker is bad. It's a tandem single pole.

 

As a sanity check I would wire the black (hot) and white (neutral) coming into the light box, directly to the fixture, leaving the switch and wiring to the switch totally out of the configuration. Sounds like a faulty fixture.

 

Sounds like a short to ground in the cable to the switch. Perhaps a cable clamp in the box or staple is too tight pinching the cable.