Bob Clukey
Member
I would like to know the minimum height of busbars in Low Voltage Switchgear. Please help!
Switchgear
- Thread starter Bob Clukey
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
Are you asking about the physical size of the bus bars themselves or where they are located within the switch gear?
I would also point out that there are different standards for switch boards, panel boards, and switch gear, but we often tend to think of them as the same thing since they have very similar functions and are often more or less functionally the same thing.
I would also point out that there are different standards for switch boards, panel boards, and switch gear, but we often tend to think of them as the same thing since they have very similar functions and are often more or less functionally the same thing.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
There is no national code standard. Testing agencies, such as UL, have guide lines but, as was pointed out, it depends on what the equipment really is and the voltages you are dealing with. For the most part the clearance for 480V is only 1" Line to ground.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
And to the point that Jim raised, I have always liked the way Baldwin Bridger put in in one of his "Powell Technical Briefs" (link below):
I once had an inspector (not a municipal guy but an employee of the consulting firm hired as a project inspector) red tag some MV equipment claiming that the bus separation was inadequate. We had had a few run-ins with him for other reasons so he was already hostile to me. I pointed out that it was UL listed, he took it upon himself to call UL and demand a field inspection (at my cost of course) with the intent of proving that the mfr we had chosen was in violation of UL standards and therefore unacceptable. The UL inspector showed up, pointed out to him that the bus separation was exactly what it was supposed to be on the UL report from when it passed. He then went one step further and told the inspector that he was flat out wrong to have questioned it, because was there no standard for what it should have been, just a test that it had to pass (what I had been saying all along). That was when I had found this Powell Technical Brief.
http://www.powellind.com/main/Uploadpdf/ptb 59 bus spacings in metal-enclosed switchgear.pdf
By the way, Powell publishes a lot of these, they are all very good reading for the industry (and no, I don't work for them).
http://www.powellind.com/pub_page2.asp?MenuCategory=4&MenuPosition=2
I once had an inspector (not a municipal guy but an employee of the consulting firm hired as a project inspector) red tag some MV equipment claiming that the bus separation was inadequate. We had had a few run-ins with him for other reasons so he was already hostile to me. I pointed out that it was UL listed, he took it upon himself to call UL and demand a field inspection (at my cost of course) with the intent of proving that the mfr we had chosen was in violation of UL standards and therefore unacceptable. The UL inspector showed up, pointed out to him that the bus separation was exactly what it was supposed to be on the UL report from when it passed. He then went one step further and told the inspector that he was flat out wrong to have questioned it, because was there no standard for what it should have been, just a test that it had to pass (what I had been saying all along). That was when I had found this Powell Technical Brief.
http://www.powellind.com/main/Uploadpdf/ptb 59 bus spacings in metal-enclosed switchgear.pdf
By the way, Powell publishes a lot of these, they are all very good reading for the industry (and no, I don't work for them).
http://www.powellind.com/pub_page2.asp?MenuCategory=4&MenuPosition=2
Just a brief about Powell...........I have been to their premises many times over the last 40 some odd years and watched them grow from a relatively small shop to the giant it is today.If you are ever in the South Houston area,a visit to their facilities would be interesting to any and all I'm sure.
dick
dick
Why are you asking the question? What is your concern or application?
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