Bonding Reverse Channel Letter Faces

[batch]

I have talked to several people who have had violations from inspectors regarding the bonding of metal reverse channel letter faces.

A reverse channel letter is a letter that sits off of the wall on standoffs. It has a clear back and a metal cover and sides. Either neon or LEDs is then mounted to the clear back and light is bounced back onto the wall.

Various methods are used to bond the metal parts on the clear backing. Usually a ring or bushing attached to a LTFM connector. The bond is made to at least on of the metal tabs that the metal face will be attached to. The face is then installed using screws.

The inspectors are saying that a bonding wire must be attached to the face. Because when we remove the screws from the face and take it off it is no longer bonded.

My argument is that we would still have to remove the bonding wire from the face to continue servicing the letter. I also compare this to the cover on circuit panel. The enclosure is grounded and the cover is attached with screws. We remove the screws to remove the panel cover and there is no bonding jumper needed.

Am I wrong or right that the cover does not need a bonding jumper if it is attached to bonded metal when installed?

Also, we use sheet metal screws to attach the face. Though the sign industry uses sheet metal screw or rivets to join many things and UL and municipal inspectors have never made a comment regarding this practice. Unless, of course, some one used a sheet metal screw to attach the EGC to the sign.

 

[zbang]

If the sign assembly has a UL sticker on it, how much authority does the inspector have over the insides?

The inspectors are saying that a bonding wire must be attached to the face. Because when we remove the screws from the face and take it off it is no longer bonded.

Why would it need to be bonded if it's 20' down sitting on a bush? Or, do they want you to have to remove the jumper when you remove the cover? The same logic says that a j box cover needs to be bonded. Doesn't make sense. I also don't see anything like this in 600 or 250.112, which refers to 600.

 

[shepelec]

Sounds like a total lack of common sense to me.:roll:

 

[HotConductor]

Does a 1900 box cover have a bonding strap? How about a trough cover? It's not required.

Take a look at this illustration:

http://207.61.100.221/intro.html

Assuming you use 3/16" or 1/4" clear lexan for your reverse channel letter backs you only need a bonding wire from your grounding ring to one face clip. A machine thread screw is required to attach the channel to the back, you cannot bond with a sheet metal screw.