Feeder EMT with EGC - bonding required?

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LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
What determines whether a feeder EGC in EMT requires bonding bushings?

My situation:

Existing:
240/120v 4-wire high-leg service
Outside fused-switch disconnect

Plan new:
Four x 250 MCM, one x #4 EGC
Inside panel, no concentric KOs
Plans call for the EGC conductor

I'm recommending eliminating the EGC, but customer is hoping to avoid plan changes. So, I need to know whether I should include labor and materials for installing bonding bushings in my comparison for my response.
 
Take a look at 250.92. But if you are carrying an EGC through the EMT, I would say add the bonding bushings at each end, and tap it upon entry and exit.
 
LarryFine said:
What determines whether a feeder EGC in EMT requires bonding bushings?

My situation:

Existing:
240/120v 4-wire high-leg service
Outside fused-switch disconnect

Plan new:
Four x 250 MCM, one x #4 EGC
Inside panel, no concentric KOs
Plans call for the EGC conductor

I'm recommending eliminating the EGC, but customer is hoping to avoid plan changes. So, I need to know whether I should include labor and materials for installing bonding bushings in my comparison for my response.
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I don't see any reason that bonding bushings (or equivalent) would be required at less than 250 volts for a feeder.
 
ptonsparky said:
That is some close bidding if you need to worry about labor and materials for two 3” grounding bushings.
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No, more at how much difference there will be in cost to help the customer (who got his own permit) decide whether to call the city to ask how involved it will be to make two plan changes. The city requires sticking to the plans regardless of compliant alternatives.

Those changes, at my suggestion, are:
1. Eliminate the redundant EGC completely (much bigger difference than just two bonding bushings).
2. Reduce specified 4" EMT to 3" (4" mistakenly chosen by customer for possible 400a upgrade later).
 
Rock86 said:
Take a look at 250.92. But if you are carrying an EGC through the EMT, I would say add the bonding bushings at each end, and tap it upon entry and exit.
Click to expand...
It sounds like you're effectively saying, "Yes, every time."
 
LarryFine said:
It sounds like you're effectively saying, "Yes, every time."
Click to expand...
Nope... I'm saying review the code. If you want to use the conduit an EGC, you would still need the bushings. if you're running the conductor, you should still be bonding the conduit. I was simply answering your question " What determines whether a feeder EGC in EMT requires bonding bushings? "
 
Rock86 said:
Nope... I'm saying review the code. If you want to use the conduit an EGC, you would still need the bushings. if you're running the conductor, you should still be bonding the conduit. I was simply answering your question " What determines whether a feeder EGC in EMT requires bonding bushings? "
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Please allow me to rephrase:

Can you tell me by saying, "You need bonding bushings if . . . " or "You do not need bonding bushings if . . . "

My presumption is that the bonding bushings are required any time there is an EGC in a metallic conduit.

Of course, the EGC would land at both the disconnect neutral and the panel EGC bus, affixed to the panel.
 
ON a 240v system feeder the only time I see a bond bushing required would be to ond loose jopint raceways (250.98) or in Classified Locations (250.100)
 
LarryFine said:
...
My presumption is that the bonding bushings are required any time there is an EGC in a metallic conduit.
...
Click to expand...
I know of no general rule that requires a bonding bushing where an EGC of the wire type is installed in a conduit that contains feeder conductors.
 
Excellent conclusions. Thanx!

I never run EGCs in metallic conduit when I design. That's why the confusion.
 
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