Let's assume you have a separately derived system consisting of a transformer in it's own enclosure and a disconnect(or overcurrent) device in a separate enclosure. You have two jumpers. One from the transformer neutral to it's own enclosure and the other from the transformer neutral through any connecting conduit to the disconnect/overcurrent enclosure and then connected to the equipment grounding terminal bar. Which of these is the system bonding jumper?
Eric Kench, P.E.
If it's not broken don't fix it
according to tjhis...it's an either or:
I'm so old when I go out to eat they ask me to pay in advance
System bonding jumper inside the disconnect enclosure is easy enough. It's just a jumper from the neutral terminal bar to the EGC bar.
Eric Kench, P.E.
If it's not broken don't fix it
The system bonding jumper is located in the enclosure that contains the GEC.
Advise is a dangerous gift, even from the wise to the wise.
Actually the GEC is located at the enclosure containing the system bonding jumper.Originally Posted by SG-1
The problem here is that I came across an old diagram from the 1990s that shows an SBJ running from the transformer neutral to the EGC terminal bar located at the disconnect. If it's in separate enclosures then which enclosure do you connect the grounding electrode conductor?
Last edited by erickench; 05-09-10 at 06:03 PM.
Eric Kench, P.E.
If it's not broken don't fix it
A grounding conductor between two different enclosures on the line side of the system disconnecting means is an equipment bonding jumper (EBJ)... no matter what the diagram calls it.
Whomever says or otherwise portrays "I am there" is a liar.
Yes, I would agree with that. I would size it in accordance with NEC Table 250.66 and refer to it as a "Supply Side Bonding Jumper" as defined in NEC 250.102(C).
Eric Kench, P.E.
If it's not broken don't fix it
The GEC is connected in the enclosure where the grounded and grounding conductors are connected to each other. The grounding and grounded conductors, in the case of a transformer, can be connected to each other at either the transformer or the OCPD, but not both. No mater where the GEC is connected, a bonding jumper will be required between the transformer and the OCPD.
Don, Illinois
"It is the first responsibility of every citizen to question authority." B Franklin
So regardless of where the SBJ is located in either the transformer or OCPD enclosures there will always be an equipment bonding jumper between the enclosures and this jumper is sized according to NEC Table 250.66.
Eric Kench, P.E.
If it's not broken don't fix it
That is correct.
Don, Illinois
"It is the first responsibility of every citizen to question authority." B Franklin
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