Leviton Timer Switch DT130 - Neutral Connected To Ground

[George7941]

The instructions call for connecting the neutral wire from the switch to ground if neutral is not available in the box. It seems like the neutral wire carries current since they want the switch neutral connected to incoming cable neutral if a neutral wire is present in the box. I don't understand this.

The complete instructions are available here https://leviton.com/content/dam/lev...n/leviton-timer-switches-dtxxx-spec-sheet.pdf

 

[jhellwig]

It is for the power to the internal electronics of the switch. You can’t power the electronics through the load like you could back in the incandescent days.

 

[George7941]

Yes, which is why I mentioned it carries current and is normally prohibited from being connected to ground. How can they justify grounding a current carrying conductor? All I can think of is - it is exempt because the current is very very low.

Some of the dimmer switches cannot be installed if neutral is not present.

 

[jhellwig]

Yes the low current. I don’t have a code book in front of me but there must be some form of rule allowing it otherwise it would not be able to be pass UL or CSA listed.

 

[George7941]

Yes the low current. I don’t have a code book in front of me but there must be some form of rule allowing it otherwise it would not be able to be pass UL or CSA listed.

As an aside, in the US, I understand a device can be grounded through the neutral if ground is not present. Maybe the rules have changed and it cannot be done any longer. A stove could be grounded through the neutral and if there is a break in the neutral cable ? Yikes! Seems very dangerous to Canadian sensibilities where it is absolutely not permitted.

 

[jhellwig]

That was allowable in the pre 1996 codes but there are still plenty of houses where it exists. The biggest problem it was never done properly in most unenforced areas so it can’t be converted to the proper way without replacing wiring.

 

[eljefino]

As an aside, in the US, I understand a device can be grounded through the neutral if ground is not present. Maybe the rules have changed and it cannot be done any longer. A stove could be grounded through the neutral and if there is a break in the neutral cable ? Yikes! Seems very dangerous to Canadian sensibilities where it is absolutely not permitted.

Stoves are good examples because the clock, 15 watt bulb, and electronics ran on 110. You can still buy a new stove and then pick your own pigtail and how it's wired, to match the outlet already in your kitchen.

New construction requires a neutral in every switch box. In the old days you might find power run to a ceiling light fixture, then a "detour" wire dips down to the switch and back. That switch wire wouldn't have a neutral, but should have a ground.

I suspect if there's a GFCI upstream of this circuit, it wouldn't be happy, and would keep tripping. Lighting and outlets are "supposed" to be separate, but you know how that goes.

 

[George7941]

Stoves are good examples because the clock, 15 watt bulb, and electronics ran on 110. You can still buy a new stove and then pick your own pigtail and how it's wired, to match the outlet already in your kitchen.

New construction requires a neutral in every switch box. In the old days you might find power run to a ceiling light fixture, then a "detour" wire dips down to the switch and back. That switch wire wouldn't have a neutral, but should have a ground.

I suspect if there's a GFCI upstream of this circuit, it wouldn't be happy, and would keep tripping. Lighting and outlets are "supposed" to be separate, but you know how that goes.

Re Stove receptacles, are there any different kinds other than the 240V/3wire with or without (old, not allowed now) ground?

I have a different understanding re neutral in every box. The lighting switch circuit you brought up is perfectly acceptable.

I am going to disagree wtih you on all your points. An upstream GFI is not going to trip because of a missing neutral in the switch box.

 

[Gyro Gearloose]

All I can think of is - it is exempt because the current is very very low.

That is the answer.

But I think eljafino is correct that if the automatic light switch circuit was powerd through a GFCI and had it's neutral connected to ground it would most likely trip. The current powering the electronics would be "missing" from the neutral wire - i.e. faulted to ground. Some GFCI's are so sensitive that the inrush current from plugging an applicance in will trip them.

 

[George7941]

That is the answer.

But I think eljafino is correct that if the automatic light switch circuit was powerd through a GFCI and had it's neutral connected to ground it would most likely trip. The current powering the electronics would be "missing" from the neutral wire - i.e. faulted to ground. Some GFCI's are so sensitive that the inrush current from plugging an applicance in will trip them.

That is not what eljefino posted. The light switch circuit does not have the neutral connected to ground. The neutral is missing in the switch box.

 

[eljefino]

If you have current going to something and it's being used and not returning on the neutral being monitored by said outlet, it'll trip a GFCI if it's over 4-6 milliamps.

A neutral became required in 2011 NEC, 404.2(C) but of course if you aren't doing major remodeling or renting the place out you're probably grandfathered in.

 

[George7941]

If you have current going to something and it's being used and not returning on the neutral being monitored by said outlet, it'll trip a GFCI if it's over 4-6 milliamps.

No one is disputing that