Open Neutral on Low Voltage Line with Swith Turned Off

[Randy]

Weird situation. I just expanded a two-gang switch box to a triple gang. The new switch is a Lutron Diva DVLV-600P. Downstream from it are a couple of outlets that I am going to plug in some rope lighting as well as two low-voltage cannister lights.

After I wired the new switch, I turned it on and tested the outlet. The outlet tested fine. However, the cannister lights did not light up. Further, when I turned the switch off, the tester was still in the outlet. Rather than just turning off, it showed a low-dim open neutral (right light was barely lit up). Crazy.

Any ideas as to what could be causing this? All of the neutrals in the switch box are clearly connected and the outlet neutral is also connected.

Thanks, Randy

[RBM]

Your weird readings on the meter may be through an led in the dimmer. The DVLV is for magnetic transformers. Is it possible that your canister lights have electronic transformers?

[Randy]

Thanks for the reply. No. They cannisters are magnetic.

[Randy]

Anybody have any thoughts?

[RBM]

Did the rope light work? Do either the rope light or the canisters work when plugged into other outlets? Did you try removing the dimmer and connect the wires together? Is it possible that you inadvertently put this outlet circuit in series with other wiring in the box?

[Randy]

Yes, the rope light works, but I am concerned about the dim open neutral light on the tester. As for the cannisters, I tried substituting a different switch, but still no light. I didn't try connecting the wires directly as these are magnetic low-voltage cannisters and I don't know the effect of bypassing the low voltage switch. Directly connecting wires results in line-voltage - wouldn't this potentially damage the cannisters?

As for other wiring in the box, no. There is one live line into the box and three lines out. Each of the lines out are running through low voltage switches (two mag, one electronic). The other two switches work fine.

Interesting side note: After I plugged in the rope light into the first outlet to test in order to answer your question, the dim open-neutral on the tester (still plugged into outlet #2) no longer was visible. I don't know what this means, if anything, but I thought it was interesting.

I think that I am going to have to pull out one of the cannisters to see if any power is getting there.

Any other suggestions are welcome. Thanks very much for your feedback so far.

Randy

[Randy]

Follow-up information. I pulled the first cannister and tested it using a simple two-wire tester. When I test it using the ground, it lights up. When I test it using the neutral, it does not. This would seem to confirm the presence of an open neutral wire, yes??

[RBM]

These are not low voltage switches, they are low voltage dimmers. If you just used a standard toggle switch or just touched the two switch wires together you are giving full voltage (120) to the transformer, which in turn is going to give 12 or 24 volts(depending on the fixture) to the lamps in the fixtures. Some Diva dimmers have an LED in them. When the switch is in the OFF position, you will get strange readings at the outlet, which is this trickle of electricity passing through to operate the LED

[RBM]

If by testing you mean, you opened the splice box on the fixture and touched the two fixture wires to the power supply wires and found it works only when you connect it to the hot and ground, yes, you've got and open neutral

[RBM]

In your original post you say that the outlet tested "fine", what are you using to determine this?

[Randy]

I used a simple two-wire tester. When I touched one wire to black and one to white, nothing. When I touched one to black and one to ground, it lit up. So clearly there is an open neutral.

[Randy]

This is based on using one of those $2 Home Depot outlet testers where it has three indicator lights (one red and two yellow). If the two yellow lights light up, the outlet tests OK. In my case, this was the result when the switch was turned on. When the dimmer was turned off, the right (yellow) light was dimly light. Typically, this would indicate an open ground. However, since this was on a low-voltage dimmer line, it might indicate something else or even nothing. The dimmer does not have an LED, per se, but it is back lit when turned off. This is likely the cause of the weird test result.

[Randy]

Correction. I meant to say an open neutral on the right (yellow) light being lit on the tester. Not an open ground.

[Randy]

Victory. I had to pull apart the cannisters. When I re-wired the power feed into the first cannister, both cans worked immediately. I still have the weird dimly lit open neutral when I test the outlets, but since everything works just fine, I can only assume that this is due to the back lighting on the dimmer. There clearly was an open neutral where the first can was wired, but this seems to be a separate issue as it is now corrected.

Thanks for your help, RBM. I really appreciate it.

Randy