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Old 03-04-2011, 10:34 PM   #16
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Replacing metal box caused issues


This particular timer does not require a neutral. Keep in mind that it was working just fine for about a week while I got around to replacing the box.

I will play with it some more tomorrow.

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Old 03-05-2011, 08:08 AM   #17
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Replacing metal box caused issues


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This particular timer does not require a neutral. Keep in mind that it was working just fine for about a week while I got around to replacing the box.

I will play with it some more tomorrow.
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it was working just fine for about a week
Are you saying you had the timer connected and working before you changed the metal box to plastic?
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Old 03-05-2011, 09:25 AM   #18
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Replacing metal box caused issues


Yes, it was working just fine for about a week. I got around to changing the box afterwards.
While I don't understand the logic, I'm going to replace the plastic with metal again. It is the only thing that changed.
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Old 03-05-2011, 10:29 AM   #19
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Replacing metal box caused issues


In your one reply you said you measured voltage on the conduit. This is not good
Do you have access to the wiring in the first light the switch feeds?
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Old 03-05-2011, 12:45 PM   #20
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Replacing metal box caused issues


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In your one reply you said you measured voltage on the conduit. This is not good
Do you have access to the wiring in the first light the switch feeds?
Wouldn't the metal conduit act as a ground? If he read from hot to the conduit, that does not mean the conduit is hot. Right? Just means it is grounded. Right?

Now if he got voltage from the conduit to the neutral, different story, right?
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Old 03-05-2011, 01:10 PM   #21
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Replacing metal box caused issues


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Thanks for all the input guys.
AllanJ - I tested voltage between conduit ends and found a reading of 70 to 75 with the switch off. When I turned on the switch, the reading went up to 110 to 115. I wasn't daring enough to bridge them by holding the wire. Can I get the same result by taping a wire to both ends with electrical tape?

Mark, I've tested that switch with another one in the house by swapping it. Wired it the same way and it worked in another location.

-Angel
That is not good. Sounds like the neutral is connected to the ground at the fixture. Right now your conduit is being used as the conductor.
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Old 03-05-2011, 03:18 PM   #22
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Replacing metal box caused issues


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Wouldn't the metal conduit act as a ground? If he read from hot to the conduit, that does not mean the conduit is hot. Right? Just means it is grounded. Right?

Now if he got voltage from the conduit to the neutral, different story, right?
The OP was measuring from conduit to conduit not hot to conduit.
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Old 03-05-2011, 07:30 PM   #23
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Replacing metal box caused issues




I guess I misread.

I think I thought he meant he measured voltage between the wires at the end of the conduit to the conduit.

Sorry 'bout that. Still not quite surewhere he was measuring.

Last edited by boman47k; 03-05-2011 at 07:34 PM.
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Old 03-06-2011, 07:18 AM   #24
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Replacing metal box caused issues


That's right, I measured from conduit to conduit.
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Old 03-06-2011, 07:52 AM   #25
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Replacing metal box caused issues


Normally conduit has to be used with metal boxes, but you can get away with this: bond around the plastic box. This is done by clamping a bare jumper wire of the same size to both of the conduit ends. (Breaker off when you do that)

But before you bond around the box or before you put back a metal box, you need to verify that there is no ground fault (or intentional use of the conduit as a neutral) on the far side (downstream; away from the panel). Use a 5000 ohm resistor instead of the bare jumper wire and after that turn the power back on and measure voltage across the conduit ends.

The purpose of the 5000 ohm resistor is to make sure you are not measuring phantom voltage. An experienced person can tell the difference between phantom voltage and an actual ground fault using other methods.

Imagine the following circuit. Panel breaker to hot wire. Hot wire to switch. Switch to light fixture. Light fixture to far conduit. Far conduit and near conduit not touching because the metal box was replaced by plastic. Near conduit back to panel. Panel and neutral bus bar (terminal strip) bonded. In this circuit, if the switch is flipped to "on" you will measure considerable voltage across the two conduit ends and the light will not go on. In this circuit, if you bonded the conduit ends, the light will go on. I am not saying that what you have is exactly this but you need to investigate. The only proper way to get the current back to the panel is via the neutral wire.

You do not have to investigate every time you replace a box or work with conduit but the fact you found a possible problem means you need to find and fix it before continuing work.

Definition: Bond -- An intentional essentially resistance free electrical connection not counting a switch or a heavy load itself (such as a heater). If A is bonded to B and B is bonded to C then A is bonded to C.

Definition: Fault -- An unwanted not necessarily resistance free electrical connection.
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Last edited by AllanJ; 03-06-2011 at 09:49 AM.
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Old 03-06-2011, 08:16 AM   #26
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Replacing metal box caused issues


The disconnected conduit should not keep his lights from working. I think there is something wrong between the lights and the switch box.
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Old 03-06-2011, 08:12 PM   #27
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Replacing metal box caused issues


I went ahead and replaced the box with a metal one this afternoon and it resolved my issue. I'm thinking of consulting an electrician to see if there is indeed a ground fault that needs to be taken care of.

I appreciate you all taking the time to help me through this.

-Angel
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Old 03-06-2011, 08:26 PM   #28
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Replacing metal box caused issues


Your conduit is providing the neutral path for the lights. The lights should have worked with the separated conduit since you have a neutral wire. I think you will find a neutral that has separated from a wire nut and is touching the conduit somewhere between the switch and the first light. Let us know what the electrician finds. Getting an electrician is a good move as you don't want to leave it the way it is.
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Old 03-07-2011, 12:21 AM   #29
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Replacing metal box caused issues


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I went ahead and replaced the box with a metal one this afternoon and it resolved my issue. I'm thinking of consulting an electrician to see if there is indeed a ground fault that needs to be taken care of.
No, this did NOT solve your issue! It made your light work, but it did not fix the serious problem. You have already verified thoroughly that you have an open neutral and a ground fault on the neutral side of the light fixture. The conduit is acting as the return path for the circuit.

This is DANGEROUS and must be fixed.

It's probably a very simple fix, too. Check the connections to the fixture. I'd bet the white fixture wire came out of the wire nut and is touching the box. If all the connections at the fixture look good then we'll progress to more diagnostics, but check that first.

Do NOT leave this as-is, it is a serious safety hazard.

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