Bonding 250mcm on 1-1/2" bushing

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Flex

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A lot of the solar installs we do require a large SBJ for the inverter, most often a 250 mcm. Some of the foreman will install the wire in conduit and have to bond it at both ends. They will typically remove the lug from the bond bushing,say an 1-1/2". Then tap the bushing for 1/4" and install a much larger lug then run the 250mcm through the lug which always seems to put a ton of stress on the bushing. Is this a proper install? I didn't think you could alter the bushing like that. If you could use a smaller bond wire with the original lug how would you size it?
 
I'm having a little problem understanding just how you end up with an SBJ in a conduit. SBJ's are required to remain inside the enclosure where it originates. It's likely a GEC.
 
Isn't that conductor suppose to be a continuous run wrapped around each grounding bushing? How are you going to wrap a 250 MCM around a grounding bushing?
 
edward said:
Isn't that conductor suppose to be a continuous run wrapped around each grounding bushing? How are you going to wrap a 250 MCM around a grounding bushing?
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Assuming we're talking about a GEC, the GEC itself is required to be continuous, but the conduit's bonding conductor is not required to be continuous with the GEC.
 
There's always this method:

IMG_0664.JPG


Personally I prefer to use these:

20130816_133109.jpg
 
Smart $ said:
Assuming we're talking about a GEC, the GEC itself is required to be continuous, but the conduit's bonding conductor is not required to be continuous with the GEC.
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Thought there was only one gec and anything else bonding to that is called a system bonding jumper
 
Flex said:
Thought there was only one gec and anything else bonding to that is called a system bonding jumper
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Here's the pertinent definitions...
Bonding Jumper, System. The connection between the
grounded circuit conductor and the supply-side bonding
jumper, or the equipment grounding conductor, or both, at a
separately derived system.
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Bonding Conductor or Jumper. A reliable conductor to
ensure the required electrical conductivity between metal
parts required to be electrically connected.
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And, FWIW, there can be more than one GEC. Each GEC is required to be continuous (i.e. irreversibly spliced or joined), in general, but bonding jumpers connected to a GEC are not.
 
Flex said:
Just took a course with the IAEI. One is gec rest are just bonds to it. Anyone else know what I am talking about
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There is a Mike Holt illustration on that subject which does show a configuration with two rod electrodes and several others including CEE. In the drawing the wire from one rod to the panel is labelled as the GEC while the wire joining the two rods is a bonding jumper. The wire to the cold water pipe is also shown as a bonding jumper, and I believe that the CEE connection is marked as a bonding jumper too. That is consistent with what you describe.

But if there are multiple electrode connections, all of which come back to the main bonding point at the panel, how can you tell which one of them is the GEC?
Examine all of them to see which ones are in fact continuous and then arbitrarily pick one? :roll:
 
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