Self grounding receptacles and wiremold

Status
Not open for further replies.
mark32

mark32

Senior Member
Location
Currently in NJ
I'm replacing all the receptacles in an office and about 25% are in wiremold. The original installer did pull an egc but did not bond the box but did ground the receptacle. The first few I came across I went through the trouble of tapping and threading the existing hole in the backplate. (For some reason none of them are threaded?) I would then bond the box (Back plate) and jump to the receptacle. I eventually ran out of time and ground screws but I have to return anyway to finish. My question, due to the fact I'm using self grounding recptacles, could I just bond the back plate or would I have to, as I've already done, jump off to the receptacle as well. I wasn't planning on spending the extra time to disassemble the box and drill and tap these back plates so saving me at least one step would help.
 
Most decent green ground screws are self tapping screws. I'm sure the ones that came with the boxes were just that. You will save time if you get ones with a ready made pigtail.

Rick
 
From the UL white book:
Metallic wireway installed in accordance with the product markings and manufacturer?s instructions is suitable for use as equipment grounding conductors,
and is Listed for grounding.

If the wireway is complete all the way to the source and the connectors and couplings are tight then it is allowed as an EGC. Hence, the box that is mounted to the back plate is bonded using the (2) mounted screws and IMO the self grounding receptacle does not require a bonding jumper.
 
I made a mistake on post #4:

Here is the correct info for the metallic surface raceway.


Surface metal raceway is considered suitable for grounding for use in circuits
over and under 250 V and where installed in accordance with the
NEC.

Surface metal raceway fittings are considered suitable for grounding for
use in circuits over and under 250 V and where installed in accordance with
ANSI/NFPA 70, ??National Electrical Code.??
 
Edward,

You are correct but the code is generic as emt, etc. can also be run as surface raceway, etc. The real issue is that by NEC rule, a raceway must be listed as an equipment ground in order to be used as such. I'm pretty sure that Wiremold is not listed as a ground because the individual parts are not solidly connected as there is no set screws. This statement is about the common 500 - 700 series steel Wiremold. I realize it's possible that there may be a similar product that is listed as grounding.

RW
 
Self grounding receptacles are only required for flush mounted box's, surface mouted box's are not required to have a jumper or self grounding receptacle if the box is a listed gounding method or bonded. see 250.146 (A) and (B)
 
You could just connect the EGC to the back plate and use a regular receptacle with one of the washers removed. A self-grounding device is not required.
 
wolfman56 said:
Edward,

You are correct but the code is generic as emt, etc. can also be run as surface raceway, etc. The real issue is that by NEC rule, a raceway must be listed as an equipment ground in order to be used as such. I'm pretty sure that Wiremold is not listed as a ground because the individual parts are not solidly connected as there is no set screws. This statement is about the common 500 - 700 series steel Wiremold. I realize it's possible that there may be a similar product that is listed as grounding.

RW
Click to expand...

Even though other conduits can be installed on the surface but a Metallic Surface Raceway is not the same as other conduits. Wiremold (trade name of Legrand) is a metallic surface raceway it is not a conduit like EMT.

This is from Legrand:
3.1.1 Mechanical Security
All raceway systems shall be mechanically continuous and connected to all electrical outlets, boxes, and cabinets, in accordance with manufacturer?s installation sheets.
3.1.2 Electrical Security
All metal raceway shall be electrically continuous and bonded in accordance with the National Electric Code for proper grounding.

This is from 2011 NEC:
Surface Metal Raceway. A metallic raceway that is intended to be mounted to the surface of a structure, with associated couplings, connectors, boxes, and fittings for the installation of electrical conductors.
 
Hi Edward, I'm really not trying to be a thorn in your side, I'm learning from all this also. So let me run this past you.
NEC is clear that everything must be listed for its application, this would mean that to be used as an EGC it must be listed as so.

This is from Legrand:
3.1.1 Mechanical Security
All raceway systems shall be mechanically continuous and connected to all electrical outlets, boxes, and cabinets, in accordance with manufacturer?s installation sheets.

Ok this is clear but I looked all over (including their installation sheets) and cannot find any specification stating that their steel Wiremold product is listed as an EGC. Because the raceway does not solidly bond at each joint I really do not think it is an EGC. I've had inspectors indicate the same viewpoint. Can you tell me of any electrical connection that connects in a comparable manner, no crimping, set screws, etc. that is listed as an EGC? (Other than some Arlington MC type push on connectors)

3.1.2 Electrical Security
All metal raceway shall be electrically continuous and bonded in accordance with the National Electric Code for proper grounding.

I just don't think the joints in that stuff would qualify as bonded.

Rick
 
wolfman56 said:
Can you tell me of any electrical connection that connects in a comparable manner, no crimping, set screws, etc. that is listed as an EGC? (Other than some Arlington MC type push on connectors)
Click to expand...

Wago's, and other similar connection devices merely rely on contact pressure to maintain conductivity
 
wolfman56 said:
Hi Edward, I'm really not trying to be a thorn in your side, You Are not, I'm learning from all this also So am I . So let me run this past you.
NEC is clear that everything must be listed for its application, this would mean that to be used as an EGC it must be listed as so. It is listed by UL

I just don't think the joints in that stuff would qualify as bonded.

Rick
Click to expand...

Well it doesn't matter what both of think, because I know you install a separate EGC in the surface raceway, just like I do. But if the surface raceway is listed as an EGC then you can use it as an EGC.
 
wolfman56 said:
Can you tell me of any electrical connection that connects in a comparable manner, no crimping, set screws, etc. that is listed as an EGC? (Other than some Arlington MC type push on connectors)


Rick
Click to expand...
those green clips that sometimes come with bath exhaust fans and such

rows of strip flourescents that use end plate as connector
 
We're overthinking this.

If anyone thinks UL tests by assembling a series of components and then passing a gazillion amps through them, their innocence is charming. Nope, you're lucky if any two components are ever assembled and have a hi-pot test performed.

That's right; it's simply amazing just how little of a connection is required to 'pass' the UL test.

I'd treat Wiremold exactly the same as I would a receptacle on an 'industrial' cover. Pigtail to the base, don't worry about the device. Since the Wiremold boxes are listed as they are, I would not apply the 'two screw' rule unless the box is made that way.
 
renosteinke said:
We're overthinking this.

If anyone thinks UL tests by assembling a series of components and then passing a gazillion amps through them, their innocence is charming. Nope, you're lucky if any two components are ever assembled and have a hi-pot test performed.

That's right; it's simply amazing just how little of a connection is required to 'pass' the UL test.

I'd treat Wiremold exactly the same as I would a receptacle on an 'industrial' cover. Pigtail to the base, don't worry about the device. Since the Wiremold boxes are listed as they are, I would not apply the 'two screw' rule unless the box is made that way.
Click to expand...

Someone has likely at some point passed a high level of current through when testing something. As you mentioned UL may not necessarily do so for basic listing evaluations, but this is because they are only looking for certain requirements and not looking for extreme limitations.
 
Thanks for all the replies. I'm glad this thread discussed something I had pondered not long ago. I had to feed a stick of Wiremold and at first I was going to use AC but I instead used MC so I could bond the back plate with the EGC but I now see, thanks to Edward's last post, that Wiremold is listed for use as an EGC. As far as the original post, I'm going to treat these receptacles just as you would a surface mounted 1900 box, like Infinity and renosteinke stated, and just bond the box (back plate). Thanks all.
 
Status
Not open for further replies.
Top