Using EGC for dimmer neutral

Status
Not open for further replies.

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
A few years ago it was the norm to use the EGC for the neutral for dimmers, occupancy sensors, and the like. And that prompted 404.2.C - include a neutral to switch locations.

As I recall, plenty of equipment was sold that used the EGC. I also recall calling Lutron (about 7 years ago) asking why they were selling two different kit - one that used the ECG and one that needed a neutral. The response was, "When the NEC and UL get their acts together and are on the same page, we will make equipment that matches that."

So, I am thinking the instructions that came with the electronic lighting control devices (those from yesteryear) said to connect the hot, neutral, egc and used their EGC connection for the few ma required.

I'm also thinking there was never any NEC code provision to do this. I looked through a 2005 - didn't see anything. Maybe I missed it. I don't recall any AHJ having a fit over no neutral for the elcd.

Remind me - what was the justification to do this?

ice
 
In my opinion the NEC has never permitted the use of the EGC as a circuit conductor, but the NFPA caved in the fight with UL.
 
IMHO the NEC never explicitly permitted the EGC to be _intentionally_ used as a circuit conductor. But the NEC permitted the use of devices that were approved by UL.

The UL standard for the devices included a maximum allowable leakage current.

As technology and insulation improved, the actual leakage became less and less, and at the same time the current required to run things such as dimmers became less and less.

Some 'smart dude' realized that they could run the dimmer using less current than the maximum allowable leakage. Thus the use of the EGC for these control currents.

IMHO the allowable leakage current standard should have followed the commonly available technology. Think about fridges tripping GFCIs. If a modern fridge trips a GFCI, then the fridge is _broken_.

At the same time, for circuits that really only require milliwatts of power, it seems reasonable to me to permit a _small_ amount of current intentionally on the EGC.

-Jon
 
At the same time, for circuits that really only require milliwatts of power, it seems reasonable to me to permit a _small_ amount of current intentionally on the EGC.
Except, of course, that as the requirement for fine grain control of occupancy sensors and dimmers gets progressively tightened, the number of those devices on a given feeder continually increases, leading to a large cumulative current on the EGC at that level.
 
The UL standard permitted 0.5mA of current per device. Even a shock from that low level can cause a reaction that could result in an injury...such as falling off a ladder.

I don't thing there was ever anything in the NEC that could be read as permitting the use of devices that use the EGC as a current carrying conductor. Sure they were often accepted by the inspectors, but there is nothing in the NEC that ever actually permitted the use of these devices.

It is too bad that the IAEI did not just issue a statement that the use of these devices is a code violation and urge the inspectors to red tag them. If that would have happened, UL would have changed the standard and the NEC would not have needed to require the neutral conductor at switch locations.
 
IMHO the NEC never explicitly permitted the EGC to be _intentionally_ used as a circuit conductor.

Just nit picking your words a bit: We all know the NEC generally doesn't have to permit us to do something, if they done want us to do something they have to say so. So what code section says I cant connect a neutral to a EGC? I couldnt find it, its one of those basic things that can be hard to find in the book.
 
Just nit picking your words a bit: We all know the NEC generally doesn't have to permit us to do something, if they done want us to do something they have to say so. So what code section says I cant connect a neutral to a EGC? I couldnt find it, its one of those basic things that can be hard to find in the book.

Maybe this:
250.24(A)(5)

(5) Load-Side Grounding Connections. A grounded conductor
shall not be connected to normally non?current carrying
metal parts of equipment, to equipment grounding
conductor(s)
, or be reconnected to ground on the load side
of the service disconnecting means except as otherwise permitted
in this article.
 
A few years ago it was the norm to use the EGC for the neutral for dimmers, occupancy sensors, and the like. And that prompted 404.2.C - include a neutral to switch locations.

I'm also thinking there was never any NEC code provision to do this. I looked through a 2005 - didn't see anything. Maybe I missed it. I don't recall any AHJ having a fit over no neutral for the elcd.

Remind me - what was the justification to do this?

ice

I don't recall anyone ever allowing this or what you call commonplace. It has and is outright against code to do so now and before.
 
I don't recall anyone ever allowing this or what you call commonplace. It has and is outright against code to do so now and before.
Do not forget that the dimmers we are talking about do not have a neutral (white wire) lead. They just have a green wire that happens go both ground the device yoke and carry a small operating current.
An inspector cannot tell the difference between a two wire dimmer with EGC and a three wire dimmer that uses the EGC as a return conductor.
If the dimmer in question had a white wire, I agree 100% that instructions telling you to connect that to the EGC would violate the NEC.
 
I don't recall anyone ever allowing this or what you call commonplace. It has and is outright against code to do so now and before.

There are / were many listed and approved devices that use the green lead from them as a current carrying conductor to compleate the circuit. It's very likely you have even installed some.
 
Do not forget that the dimmers we are talking about do not have a neutral (white wire) lead. They just have a green wire that happens go both ground the device yoke and carry a small operating current.
An inspector cannot tell the difference between a two wire dimmer with EGC and a three wire dimmer that uses the EGC as a return conductor.
If the dimmer in question had a white wire, I agree 100% that instructions telling you to connect that to the EGC would violate the NEC.
Yes

There are / were many listed and approved devices that use the green lead from them as a current carrying conductor to compleate the circuit. It's very likely you have even installed some.
Yes

These are the issues.

ice
 
Maybe this:
250.24(A)(5)
The green wire used as the grounded conductor by the device isn't really a grounded conductor. I am not sure that this section can be cited to show a violation...maybe the identification rules in Article 200 could be used to show a violation.

I know that in earlier posts, I said that we can't use the EGC as a grounded conductor, but after some more review, I am not sure that there is a direct rule in the NEC that actually says we can't.
 
The green wire used as the grounded conductor by the device isn't really a grounded conductor. I am not sure that this section can be cited to show a violation...maybe the identification rules in Article 200 could be used to show a violation.

I know that in earlier posts, I said that we can't use the EGC as a grounded conductor, but after some more review, I am not sure that there is a direct rule in the NEC that actually says we can't.

Hince the word "Maybe";)

Maybe this:
250.24(A)(5)
 
Status
Not open for further replies.
Top