Bus Drop ground

Status
Not open for further replies.

Dave58er

Senior Member
Location
Dearborn, MI
How do you guys normally terminate the ground in bus drop cable inside a disconnect or machine panel?

I normally do a kind of braiding that interlocks them and then land them under 1 lug. Is this even legal?

Maybe I should be putting them into a wire nut or split bolt and coming out with an appropriately sized single conductor, then landing it under the lug?
I just wouldn't like that in a disco.

What do you guys think?
 

Dave58er

Senior Member
Location
Dearborn, MI
I like that idea gregg. Seems like it could make for a "clean" installation.
If I find out the way I've been doing it (combining the three small grounds into one big conductor) isn't up to code I'll try your idea. :smile:
 

benaround

Senior Member
Location
Arizona
Dave,

I'm sure the lug is not rated for 3 conductors, that would be the code

violation. The grounding bus that Greg suggested would be the way to go.
 

mdshunk

Senior Member
Location
Right here.
Can someone post a link to a picture of the type of buss drop cable being discussed in this thread?

I've seen two types of buss drop cable. One had a grounding conductor and a steel aviation cable type strain member. The other had a grounding conductor and several nylon cord type strain members. I've never seen one with no grounding conductor and three combination strain members/grounding conductors.
 

benaround

Senior Member
Location
Arizona
Marc,

Do a quick 'google' search bus drop cable go to Southwire and there it will

be. It has 3 insulated cond. and 3 smaller grd. wires.
 

Dave58er

Senior Member
Location
Dearborn, MI
benaround said:
I'm sure the lug is not rated for 3 conductors, that would be the code violation.
That's my thought too. :smile:

I agree that 3 conductors under a lug listed for one is a violation. But is this really three conductors? I haven't checked the actual area's of the wires but the grounds are much smaller. I'm sure they wouldn't meet any sizing chart in 250 individually.

If they have to be combined to be the proper size EGC then are they one conductor?

I know I may be splitting hairs here but I've seen hairs split on this site with issues that are much more in the realm of something that may not actually even happen. This is something I sometimes encounter and I'd like to know if I'd be right if I forced someone to treat the grounds as 3 individual conductors. :smile:
 

mdshunk

Senior Member
Location
Right here.
Dave58er said:
This is something I sometimes encounter and I'd like to know if I'd be right if I forced someone to treat the grounds as 3 individual conductors. :smile:
I kinda doubt it. It's not really legal to parallel conductors that small, but it is a UL listed cable assembly, so that doesn't really apply. That would be a good question for the manufacturer's engineering rep. After all, we're permitted to gather the strands of type SE cable and concentric neutral URD to form one conductor.
 

Dave58er

Senior Member
Location
Dearborn, MI
mdshunk said:
After all, we're permitted to gather the strands of type SE cable and concentric neutral URD to form one conductor.
I wish I would have thought of that point!:)

That's what I'm getting at though. Say I tell some guy working for me he has to use a ground bar, am I wrong? Maybe my apprentice will ask this question. I'd like to give an informed opinion.
I'm not worried about passing an inspection because these installations don't normally get inspected. And I'm sure that either way will be a safe installation, but I still have that nagging problem of sometimes wanting to know what the heck I'm talking about.
 

benaround

Senior Member
Location
Arizona
Marc, Dave,

Back at 'southwire' it says 3 ground wires, one for each conductor. WOW I

seem to be getting dumber by the day!!!

The point, that would be 3 conductors IMO even if twisted into one like SE

Cable, if it said 3 ground wires to form the EGC or something to that affect

maybe that could be considered 1 conductor.

Other cable co. may be different ,so depending on what you get for cable

may be the only way to know how to ground it properly. DONE.
 

mdshunk

Senior Member
Location
Right here.
benaround said:
Back at 'southwire' it says 3 ground wires, one for each conductor. WOW ...
I concurr. WOW!

Southwire sure has a great, informative site. I should poke around there more often. It is a letter I downloaded off their site once upon a time that has saved my butt on a regular basis. It basically said that if the jacket of installed NM cable was "scuffed" as the cable was installed, and the internal conductor insulation was not damaged, then the jacket did its job and jacket repair is not required. I Tlove that satement. That's a little off topic. Sorry 'bout that.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Mark,
I kinda doubt it. It's not really legal to parallel conductors that small, but it is a UL listed cable assembly,
310.4 does not apply to equipment grounding conductors so there is no minumum size that can be used in parallel.
Don
 
Status
Not open for further replies.
Top