EMT Ground Bushings Necessary?

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davet

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If running conduits with parallel conductors in each conduit, (2-2.5" emt"s /
3-350kcm in each pipe / no nuet.) are grounding bushings necessay at both ends?
Dave T

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iwire
 
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Assuming these are feeders than most likely no.

If it is over 250 to ground and the EMTs terminate in concentric KOs than maybe.
 
davet said:
If running conduits with parallel conductors in each conduit, (2-2.5" emt"s /
3-350kcm in each pipe / no nuet.) are grounding bushings necessay at both ends?
Dave T

Email address removed.

Use PMs to exchange emails.

iwire
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Bond bushings 250.92.... at both ends would be to reduce a Choke Coil effect? Also, just bond the Metal pipe at the supply or line side.
 
For feeders, bonding bushings are almost never required. In fact with the exception of service raceways or conduits stubbed into an open bottomed switchboard, you almost never need them.
 
Trevor all I would add is that Don has pointed out that the larger concentric KOs found in disconnects etc. are not listed for grounding.

So above 250 volts to ground you may need to use a bonding bushing.

But I agree in general I will not need them in feeders. :)
 
dcspector said:
Bond bushings 250.92.... at both ends would be to reduce a Choke Coil effect?
Click to expand...

The Choke effect is not an issue with feeders or service conductors.

The Choke effect comes in when you run a single conductor in a metal raceway as with a GEC.
 
iwire said:
Trevor all I would add is that Don has pointed out that the larger concentric KOs found in disconnects etc. are not listed for grounding.

So above 250 volts to ground you may need to use a bonding bushing.

But I agree in general I will not need them in feeders. :)
Click to expand...


I would agree. Since you mentioned it in an earlier post I left it out of mine. Many of the disconnects that I see now, particularly Square D, have tangential KO's which do not require a bonding bushing.
 
flanative78 said:
Could you please elaborate on why you would not need bonding bushings on a feeder......
Click to expand...

Lets look at another way.

EMT is listed in 250.118 as an equipment grounding conductor.

EMTs fittings are listed as suitable for grounding.

So why would we need bonding bushings on a feeder?
 
Greg,

Why do you say to bond on the supply or line side of the feeder? Not that

it's a problem, I always figured the line side has a good bond, so I like to

bond the load end, I'm looking for your reasonning.
 
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