0 ohms phase to ground on buss duct.

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jmargolis79

Member
Location
minneapolis
We had to install to used buss duct switches this morning. Put the first one up and when we ohmed it out before re-energizing it, we had 0 or 1 ohm from all phases to ground. We then removed the newly installed switch and took reading again and had the same readings. What would cause this reading? After talking to a few of our people we energized it without any problems.

This duct has large machines, with heating elements in them, flourensent lighting, and some 120/208 panels. I am unsure as to what else may be one this.
 
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zbang

Senior Member
Location
Roughly 5346 miles from Earls Court
Ohmed out what? The bus? There isn't much point in taking readings like that of the bus duct unless all the loads are disconnected from the bus. (And, I assume that you didn't take any readings before mounting the switch, they would have shown very low resistance then.)
 
brian john

brian john

Senior Member
Location
Leesburg, VA
When installing busway;

Megger each piece upon receipt, prior to installing, after installing at 1000 VDC, do the same with each switch.

one bad switch, coupling or section can compromise the complete install.
 
electricalperson

electricalperson

Senior Member
Location
massachusetts
brian john said:
When installing busway;

Megger each piece upon receipt, prior to installing, after installing at 1000 VDC, do the same with each switch.

one bad switch, coupling or section can compromise the complete install.
Click to expand...

last time we installed busway we just threw it up and hoped it worked. they say it takes too long to megger. i know better now thanks to you and everyone here. the busway i was talking about was little thin stuff we fed with 100 amp 3 phase 120/208v and had a few busheads on it feeding pieces of small equipment. im sure the stuff you put in makes my install look like childs play :(
 
ohmhead

ohmhead

Senior Member
Location
ORLANDO FLA
Well we agree with all the post you megg each new section you megg as you install it meaning putting it together then you know your fine .

If you have a load connected to a buss yes you will get what ever reading is the resistance of that element of that load in most cases you will get low ohms reading my question is were you megging or just using a ohm meter ?


But if we have a exsiting buss duck and were just adding a switch its kinda not a bigg deal just plug it in tighten up and turn it on is kinda not going to short out if it was on the line before you started .
 
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