Earthing tray

[brizospark]

Does cable tray have to be earthed / bonded in ALL cases?

 

[johnboy6083]

no, as long as it is not extraneous. i think thats its good practice to bond it at one end though, and i always do. if fresh air bends are used, then i bond between the bits too.
I dont fit links betwwen each lenth of tray however, as the joiners are more than adequate for this purpose.

 

[brizospark]

so when is tray classed as extraneous?

 

[Deleted member 26818]

I think he might have meant exposed.
Basically, if it can be touched and can carry an earth fault current, then it should be earthed.
If it was extraneous, then it would require bonding.

 

[High Tower]

I always bont tray, it takes 5 seconds to do and its peace of mind, although as John says i only bond in one place

Brizo it becomes extraneous when not conected to any exposed condutive part and does not for part of a electrical install such as comms etc

 

[High Tower]

I think he might have meant exposed.
Basically, if it can be touched and can carry an earth fault current, then it should be earthed.
If it was extraneous, then it would require bonding.

Yeah that was Johns point if it is Extraneous then it WILL need to be bonded.

 

[brizospark]

can anyone else elaborate on when and when not tray is 'extraneous'

 

[Deleted member 26818]

My understanding is:
Extraneous is something being not part of a wiring system which can introduce an earth potential difference.
Exposed is something which is part of a wiring system, that could become live under fault conditions.

 

[johnboy6083]

basically mate, if it imports a potential from outside the building, ie another building, or outside brackets that are bolted to the ground ect

 

[telectrix]

My understanding is:
Extraneous is something being not part of a wiring system which can introduce an earth potential difference.
Exposed is something which is part of a wiring system, that could become live under fault conditions.

IMO containment is part of the wiring system and so is an exposed conductive part, not extraneous. correct me if i'm wrong.

 

[Deleted member 26818]

IMO containment is part of the wiring system and so is an exposed conductive part, not extraneous. correct me if i'm wrong.

I don't belive you are.

 

[johnboy6083]

I don't belive you are.

you may have a point. i may well have to concede on this one.

 

[topquark]

so when is tray classed as extraneous?

Extraneous coming either through the ground like water/gas main or as in the case of cable tray, it would be extraneous if it came from outside the building (IE from another building).

 

[brizospark]

ok so what is the summary of this? should tray be earthed / bonded?

 

[Des 56]

Originally Posted by brizospark
so when is tray classed as extraneous?

I agree with topquark,if it exits and returns into a building or it spanned between 2 buildings or simillar