Grounding to building steel

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powersystems

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We are working in a hi rise building. There seem to be some grounding issues. While doing some demo work when you cut across a BX (with the circuits turned off) we get a small spark from the neutral to the casing but no readings from neutral to ground in the panel. There is a 480 volt riser busway and on each floor there are transformers to step down the voltage to 120/208. Normally when we install a transformer we bond xo,the case the line & load egc to building steel. None of the building transformers are bonded to building steel but apparently the original building manual from 1985 states to bond the transformer to the source egc but specifically states not to bond it to building steel. Do you think these transformers should be bonded to building steel or is there a reason not to do this.

TIA

Kevin
 
The neutral is isolated after the transformer but the grounds are not isolated.
What article states that we need to bond to building steel and has this changed since 1986??

Thanks
Kevin
 
I found the article
I also found that it states in the 84 code that the steel needs to be bonded
so I am not sure why the building documents said not to, either way i have to believe it would be better to bond these transformers to building steel than not.


Thanks for the input

Kevin
 
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