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

>> Home   >> Electrical-Photos   >> Classifieds   >> Subscribe to Newsletter   >> Store  
 

Photos of the Week:

Avalon Theatre
Avalon Theatre-1 2 3 4

Random Gallery Image:
Recent Gallery Topics:
What in Tarnation?
What in Tarnation?
by timmp, September 10
Plumber meets Electrician
Plumber meets Electrician
by timmp, September 10
Who's Online Now
0 members (), 247 guests, and 30 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Joined: Oct 2000
Posts: 2,749
Member
QUESTION FROM: John J. Deery ,

Joe my question is about 250.97. If you run a branch circuit to a safety switch and the conduit enters the enclosure through concentrics or eccentrics, are you required to use bonding bushings when the voltage excedes 250 volts to ground and you pull an equipment grounding conductor and bond it to the enclosure?

My concern: "Is the conduit being properly bonded?"

I spoke to Kevin Huss from Square D at 800-634-2003 TEC support, and was told to date Square D does not have an enclosure on the market with pre-stamped ko's listed by U.L. for the purpose of bonding.

We have new branch circuits being run at our plant 480 volts where the conduits are being landed in pre-stamped ko's of Square D enclosures with equipment grounding conductors, but are relying on the eccentrics and concentrics to bond the conduits.

Thanks


Joe Tedesco, NEC Consultant
Horizontal Ad
Joined: Mar 2001
Posts: 2,056
R
Member
The conduit needs to be effectively bonded to the installed EGC through a bonding bushing because if a fault developed in the raceway, the return path may not have a low enough impedance to assure opening of the OCPD.
Don,
are you wondering if the conduit is effectively bonded at the supply end, and therefore not required to be bonded through a bushing at the switch end?

Joined: Apr 2002
Posts: 2,527
B
Moderator
Some suggestions...Square-D makes NEMA-12 [NOT '12K' or ‘AWK’ suffix] XOP fusible disconnect switches without knockouts. Westinghouse/C-H makes NEMA-12 breaker enclosures of similar construction. Many 5½" depth panelboard cans are available with 'blank endwalls.' The 12’s are equal or somewhat less in price compared to 3R. ‘NOKO’ NEMA-1, -3 and -3R screw-cover gutters and pull cans are out there too.

KO reducing rings are {or should be} suicide.

Joined: Nov 2000
Posts: 2,148
R
Member
Redsy,
That is exactly what I was thiniking. Most code experts say that only one end of a service raceway requires bonding, so I would think that if the supply end was properly bonded, there would be no need to bond the load end, assuming that the EGC is used to bond the enclosure.
Don(resqcapt19)


Don(resqcapt19)

Link Copied to Clipboard
New Page 2
Powered by UBB.threads™ PHP Forum Software 7.7.5