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
Industrail Control Panel bonding per 409.108
by sparkyinak
Yesterday at 06:29 PM
Calling all Non-US members!! (Non-US only)
by aussie240
12/07/16 02:39 AM
Photo Upload Tutorial
by DanK
12/06/16 11:35 PM
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 10
Texas_Ranger 8
sparkyinak 8
Potseal 6
Who's Online
2 registered (crselectric, mbhydro), 232 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#129424 - 03/08/05 02:28 PM how do I ground a 25V circuit?
unsaint32 Offline
Member

Registered: 08/24/04
Posts: 16
Loc: eden prairie, MN, USA
I have 277/480 Y at work and I need to hook up an exit sign that uses 25V. So, I am planning to use a transformer, I assume 277/25V transformer.
I looked up the code book which said, I need to ground a system if it is less than 50V, and if it is fed by a supply system of more than 150V.
But, how do I system ground the secondary side, which is the exit sign? Run a grounding wire to concrete? Even if I did that, what do I connect it to? All the electrodes, the building metal structure, and water pipes are being used as electrodes for the building.

Am I wrong about the code?

Jon


What is the "objectionable current" at the code

Top
#129425 - 03/12/05 01:32 PM Re: how do I ground a 25V circuit?
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
I'm not up on the finer code requiements on this sort of situation, but you could ground the 25V side by just linking one side of the secondary to the equipment grounding conductor (which would also be grounding the transformer frame).

Top
#129426 - 03/14/05 10:37 AM Re: how do I ground a 25V circuit?
unsaint32 Offline
Member

Registered: 08/24/04
Posts: 16
Loc: eden prairie, MN, USA
what about the neutral of the secondary side? Do I need to bond that to the same side's equipment grounding bus and after that, make connection to the primary side eqiupment grounding conductor?

thanks

Top
#129427 - 03/17/05 11:09 AM Re: how do I ground a 25V circuit?
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Yes, you would need to bond the neutral on the secondary to ground. Some of our code experts might throw in details of any specific code-requirements here.

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