Bonding Aluminum Cable Tray

Status
Not open for further replies.
J

Jerry Albertelli

Member
Location
Vidor
I've have two B-Line aluminum Cable Trays carrying two 4/c #12 copper wires. I'm feeding two 6.9 FLA pump motors protected by a 30 amp fuse disconnect. What size Bonding Jumper do I need to bond the two cable trays together. According to 250.122, #10 shows suffice. However, the Note below the 250.122 table specifically states "Where necessary to comply with 250.4(A)(5) or (B)(4), the equipment grounding conductor shall be sized larger that given in this table. *See installation restrictions in 250.120."
Am I getting the terminology "grounding conductor" confused with Bonding-Jumper needed for my two trays? Because If I'm correct, 250.120(C) states that I need a #6, unless my #10 wire is protected.:? Please Advise??
 
regardless of what the tables say as far as EGC sizes go, you are still required to provide an effective ground fault path. In rare cases that may result in you needing to have a larger than expected EGC.

you might also have to upsize the EGC to account for a conductor that was used that exceeds the minimum size required.

personally, I would use the plates that come with the cable tray that mechanically holds the trays to each other. they are listed as being a bonding means.

The only thing that needs bonding then is to bond the source end of the cable tray system.
 
Jerry Albertelli said:
I've have two B-Line aluminum Cable Trays carrying two 4/c #12 copper wires. I'm feeding two 6.9 FLA pump motors protected by a 30 amp fuse disconnect. What size Bonding Jumper do I need to bond the two cable trays together. According to 250.122, #10 shows suffice. However, the Note below the 250.122 table specifically states "Where necessary to comply with 250.4(A)(5) or (B)(4), the equipment grounding conductor shall be sized larger that given in this table. *See installation restrictions in 250.120."
Am I getting the terminology "grounding conductor" confused with Bonding-Jumper needed for my two trays? Because If I'm correct, 250.120(C) states that I need a #6, unless my #10 wire is protected.:? Please Advise??
Click to expand...
There is a move afoot to get rid of the term "equipment ground" and substitute "bonding". It's supposed to make things easier but I think it just makes Art. 250 more confusing.

#10 is the right size equipment grounding conductor for a 30A circuit but if your equipment grounding conductor is out where you can touch it then it needs to be #6.
 
ActionDave said:
There is a move afoot to get rid of the term "equipment ground" and substitute "bonding". It's supposed to make things easier but I think it just makes Art. 250 more confusing.

#10 is the right size equipment grounding conductor for a 30A circuit but if your equipment grounding conductor is out where you can touch it then it needs to be #6.
Click to expand...

petersonra said:
where does it say that in the code?
Click to expand...

iwire said:
250.120(C)
Click to expand...
That's all fine, but let's not forget, confuse, or obscure that details determine what is required...

If there is no EGC in the cables, aluminum cable tray can be used as the EGC. 390.60 covers grounding and bonding, and among other criteria, 390.60(B)(4) states bonding jumpers shall be sized per 250.102... which leads us specifically to 250.102(D), and therein sized per 250.122. Note this jumper is referred to as an Equipment Bonding Jumper in 250.102(D) and therefore not subject to the requirement of 250.120(C) regarding Equipment Grounding Conductors. However, 250.102(E) does apply regarding the installation of said bonding jumper...
 
Last edited:
So to clear the obscurity up a little......I guess I deciphered the foot-note below 250.122 properly stating that if it's unprotected, then it needs to be no less than a #6 which most everyone is using #4 and being done with it....Thanks!
 
if it ever comes up, I will just use min #6 or larger. easier than arguing with people about it and the cost is not normally all that much different.
 
ActionDave said:
There is a move afoot to get rid of the term "equipment ground" and substitute "bonding".
Click to expand...
Thats been tried for many code cycles, Don G started it some time ago. We'll see what happens
What we need is a two articles. At least now its grounding and bonding.
 
tom baker said:
Thats been tried for many code cycles, Don G started it some time ago. We'll see what happens
What we need is a two articles. At least now its grounding and bonding.
Click to expand...
Yes. We've quibbled a bit about it here. Apparently changing to "bonding" had positive results in Canada. To me it sounds like a conversation with an electrician who sips tea from a cup with his pinky finger extended....."Oh my dear chap that's not equipment grounding, that's bonding," chuckle, chuckle, light pat on the back.

Whatever. It's not a hill I'm willing to die on. What we are stuck with now is an absolute wreck though.
 
When used outdoors where there is ground movement you also need to provide a flexible bond connection. The picture below shows a cable tray run over the top of a capped landfill. The bonding jumper is to the right of where the cables that are looped up in the air.

IMG_20140807_131212777.jpg
 
Status
Not open for further replies.
Top