Transformer GEC

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Dexie123

Senior Member
Hello all

When installing a transformer and you bring in your GEC that has been piped out in conduit continuously is it required to take the GEC (#4) and bring it to a bonding bushing and then to your "xo"? Or ground lug?

Thanks
 
Yep.... Emt....

Goes from EMT to about 2' of flex (greenfield) that has an external bond (#6) on the outside. The ko is not cocentric so that's not an issue.

I think no but it came up today so when I ever get confronted I put my tail between my legs (no confidence) and come ask you guys!

Thanks
 
Dex,

When installing an xfmr I bolt 2- 3 hole lugs to xo for the following connections:

1. EGC from supply feed
2. GEC to nearest GE
3. N to isolated neutral bar in load side disco(s)
4. BJ to xfmr case
5. System bonding jumper to ground bar in load side disco(s)
6. Internal BJ to load side disco(s) when using flex or liquidtight

An external BJ is limited to 6'.
 
Dexie123 said:
Goes from EMT to about 2' of flex (greenfield) that has an external bond (#6) on the outside. The ko is not cocentric so that's not an issue.
Click to expand...

What's the reason for the #6 on the outside of the flex? How is it attached?
 
HotConductor said:
Dex,

When installing an xfmr I bolt 2- 3 hole lugs to xo for the following connections:

1. EGC from supply feed
2. GEC to nearest GE
3. N to isolated neutral bar in load side disco(s)
4. BJ to xfmr case
5. System bonding jumper to ground bar in load side disco(s)
6. Internal BJ to load side disco(s) when using flex or liquidtight

An external BJ is limited to 6'.
Click to expand...

Ya good way to do it for sure HotConductor.

RUWired said:
It's not required to do it that way but it is required to be bonded. See 250.64(E)
Click to expand...

Well the transformer is required to be bonded yes. The internal bond came that way with a strap internally. Just wasn't sure what the deal was with the bonding bushing is all.

Infinity that's a good question. I know if the flex is less than 6' and it's rated as an acceptable ground it's not needed. We're just doing it as an extra. It's a number 6 that is connected in with lugs to the screws.
 
I may be missing something, but I would think if you have not bonded bothe ends of the metallic conduit containing the GEC you would be in violation of 250.64(E)
 
RUWired said:
Beaware the aluminum strap you see is most likely the transformer core bonding jumper and not the ox jumper.
Click to expand...

I agree and I hear this all of the time that the transformer came factory bonded. I've yet to see one that was factory bonded. Those straps typically bond the transformer core to the casing.

If you closely at the bottom left you'll see the factory metal bonding strip. The XO is bonded to the equipment grounding buss by the jumper to the right.


20080209_59.JPG
 
Thanks guys!

Well I have the GEC bonded directly to the XO. Are you saying I need to take another bond wire from the XO to the transformer chassis? Even if I have the GEC attached to the bonding bushing and then to the XO?
 
Dexie123 said:
Thanks guys!

Well I have the GEC bonded directly to the XO. Are you saying I need to take another bond wire from the XO to the transformer chassis? Even if I have the GEC attached to the bonding bushing and then to the XO?
Click to expand...


IMO, yes a bonding jumper is still required.
 
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