The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Sprinklered equipment 26-008
by bigpapa
Yesterday at 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
Earthquake in New Zeeland
by RODALCO
11/27/16 11:25 PM
Calling all Non-US members!! (Non-US only)
by Tjia1981
11/27/16 06:33 AM
New in the Gallery:
12.5A through 0.75mm flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 15
HotLine1 10
Trumpy 8
Texas_Ranger 8
sparkyinak 7
Who's Online
0 registered (), 106 Guests and 5 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#81641 - 09/04/02 03:59 AM 1.5, 3, and 5kva transformer grounding.
jlhmaint Offline
Member

Registered: 05/25/02
Posts: 208
Loc: Fredericktown, OH, U.S.A
which section in the code will cover this and explain. please there are some different views at work and would like to clear this up. some are just hooking a ground to the metal case, others are tying X1 to ground and grounding the case. I have seen it done both ways or not at all. note these are typical 480V to 120 V

[This message has been edited by jlhmaint (edited 09-04-2002).]

Top
2014 / 2011 NEC & Related Books and Study Guides
#81642 - 09/04/02 10:03 AM Re: 1.5, 3, and 5kva transformer grounding.
electric-ed Offline
Member

Registered: 07/08/02
Posts: 184
Loc: Canada
I can't quote code rules, as I do not know the NEC well enough, but the basic principles of grounding and bonding are similar everywhere.

The sketch below shows grounding and bonding for a typical single phase stepdown transformer.



Ed

Top
#81643 - 09/04/02 11:57 AM Re: 1.5, 3, and 5kva transformer grounding.
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
These are Separately Derived Alternating-Current Systems as covered in 250.30. Eds drawing is right on the mark.
Don
_________________________
Don(resqcapt19)

Top
#81644 - 09/04/02 07:05 PM Re: 1.5, 3, and 5kva transformer grounding.
jlhmaint Offline
Member

Registered: 05/25/02
Posts: 208
Loc: Fredericktown, OH, U.S.A
ok that pic shows exactly how we do it in our building but we have seen some from our other building that were not like that or no ground or bond at all. Thanks

Top
#81645 - 09/04/02 07:48 PM Re: 1.5, 3, and 5kva transformer grounding.
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
I may be missing something, but don't {99NEC} 250-30 and 250-26 fairly well cover the matter? The sizes listed are all above 1000VA. Probably one aspect of the ‘building steel’ versus “case” ground, it would seem more critical if the wiring runs extended out of a local area. [In the case of an open secondary bonding jumper, it’s maddening to have to do much troubleshooting on ungrounded 120V controls.]

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals