Bushing

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Alwayslearningelec

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So does the M in MIGB stand for metallic or malleable. If using EMT which type of grounding bushing material would most likely be used?
 
So another related question. So if a grounding bushing is required would it HAVE to be at every box, enclosure etc. the conduit "terminates" at or possibly only at specific point along the run? So some locations along the same run could have a regular bushing and some could have a grounding?
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Alwayslearningelec said:
So another related question. So if a grounding bushing is required would it HAVE to be at every box, enclosure etc. the conduit "terminates" at or possibly only at specific point along the run? So some locations along the same run could have a regular bushing and some could have a grounding?
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Grounding bushings are rarely required. Do you have a specific type of installation that requires them?
 
Alwayslearningelec said:
So another related question. So if a grounding bushing is required would it HAVE to be at every box, enclosure etc. the conduit "terminates" at or possibly only at specific point along the run? So some locations along the same run could have a regular bushing and some could have a grounding?
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Not necessarily every box. Think of a MIGB as possibly being needed at a connector/ box/cabinet, like Larry said depending on the voltage, if it's a service, and if it's got concentrics. It may be needed at some terminations and not others - unless it's a service then you need one at every connector (well some additional bonding, could be a BL or wedge).
 
Alwayslearningelec said:
So another related question. So if a grounding bushing is required would it HAVE to be at every box, enclosure etc. the conduit "terminates" at or possibly only at specific point along the run? So some locations along the same run could have a regular bushing and some could have a grounding?
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The intent of such item is for when there is or possibly could be an impaired bond by a regular locknut for various reasons, it just gives an alternate path that is more assured will be a sufficient path.

A metal raceway entry into a non metallic enclosure or where there is no enclosure wall say bottomless gear or where transitioning from metal raceway to open conductors also would be a place where a bonding bushing very well might be used
 
Yes but what's the difference between a concentric KO and one you punch yourself because one you need the migb and one you don't correct?
 
infinity said:
Why does it not make sense? The locknut on the raceway or EMT connector makes the metal to metal connection to the box.
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Yes. Is it a concentric KO one that's partially imprinted to be knocked out? So whether you knock out your own holes or have the concentric you still need lock nuts
 
Alwayslearningelec said:
Yes. Is it a concentric KO one that's partially imprinted to be knocked out? So whether you knock out your own holes or have the concentric you still need lock nuts
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Yes you'll need locknuts. Also if the voltage is 208Y/120 or 120/240 even with concentric KO's bonding bushings would only be required on service raceways.
 
infinity said:
Yes you'll need locknuts. Also if the voltage is 208Y/120 or 120/240 even with concentric KO's bonding bushings would only be required on service raceways.
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Yes but I'm referring to the grounding bushing. Did you say that whether the ko's are concentric or punched out yourself makes a difference if a grounding bushing is required??
 
Alwayslearningelec said:
Would you need a seprate bushing( whichever type) for this hub?
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No. The insulated throat is all that's required.

Alwayslearningelec said:
Yes but I'm referring to the grounding bushing. Did you say that whether the ko's are concentric or punched out yourself makes a difference if a grounding bushing is required??
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What voltage are you referring to? For less than 250 volts to ground a bonding bushing is not required even with concentric or eccentric KO's.
 
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