250.118 and EMT

[OrlandoCB]

Good evening folks

Just finished most of 250 and feel quite confused about some aspects of it, specially after reading 250.118

According to 250.118 EMT is consider a EGC, therefore for example in case of a supply side bonding jumper, if my raceway is EMT that ends in a Metal enclosure for the service disconnection device, Do I need to add the supply side bonding from my pipe/enclosure to the ground bus bar?

Also please correct me if wrong, in case of outlets from branch circuits, if again I use EMT as raceway all I need to do is connect the outlet (Lets say a receptacle) to the metallic enclosure and this will count as it being grounded?

And from the handbook (Example exhibit 250.35) there are examples of connections between EMT and the ground bus bar, and then from the metal enclosure to the same bus bar, if they are bot supposed to be EGC according to 250.118, why is this connection with bonding jumpers needed at all ?



Thanks for your support!!!

 

[david]

Good evening folks

According to 250.118 EMT is consider a EGC, therefore for example in case of a supply side bonding jumper, if my raceway is EMT that ends in a Metal enclosure for the service disconnection device, Do I need to add the supply side bonding from my pipe/enclosure to the ground bus bar?

Thanks for your support!!!

Yes EMT is an approved conductor for equipment grounding

Please see 250.92 for metal raceways and bonding at services, the bonding is because it is metal its not because it is or is not an equipment ground

 

[david]

Good evening folks

Also please correct me if wrong, in case of outlets from branch circuits, if again I use EMT as raceway all I need to do is connect the outlet (Lets say a receptacle) to the metallic enclosure and this will count as it being grounded?

Thanks for your support!!!

Self grounding Rec have to insure metal to metal contact
you may need to break the metal rabbit ears off the device to insure that contact

 

[david]

Good evening folks
And from the handbook (Example exhibit 250.35) there are examples of connections between EMT and the ground bus bar, and then from the metal enclosure to the same bus bar, if they are bot supposed to be EGC according to 250.118, why is this connection with bonding jumpers needed at all ?
Thanks for your support!!!

If you are referring to GEN that are Separate systems then you are referring to the bonding requirements that are needed for that system

 

[OrlandoCB]

Yes EMT is an approved conductor for equipment grounding

Please see 250.92 for metal raceways and bonding at services, the bonding is because it is metal its not because it is or is not an equipment ground

Thanks mate!! Really appreciate the help !

 

[OrlandoCB]

Also for 250.118 its seems that there are specifications for some tubing on which scenarios they may act as a EGC ( for example Flexible metal conduit specifies that it can only be used in circuits that end on a 20 amps CB or less) but or cases such as 250.118 (4) "Electrical metal tubing", is therr any specification on how to size it to act as a EGC?

Is there any table similar to 250.122 on how to size the EMT to be suitable as a EGC for x amount of circuit ampacity ?

Thanks for your time and support !!!

 

[480sparky]

Also for 250.118 its seems that there are specifications for some tubing on which scenarios they may act as a EGC ( for example Flexible metal conduit specifies that it can only be used in circuits that end on a 20 amps CB or less) but or cases such as 250.118 (4) "Electrical metal tubing", is therr any specification on how to size it to act as a EGC?

Is there any table similar to 250.122 on how to size the EMT to be suitable as a EGC for x amount of circuit ampacity ?

Thanks for your time and support !!!

It's already an over-sized conductor. It's size is determined by the conductors it encompasses. You can always use a larger conduit, which is basically the same as using a larger wire, if you want to. But you can't use EMT that's 'too small' because then you wouldn't be able to fit the wires in it.

 

[OrlandoCB]

It's already an over-sized conductor. It's size is determined by the conductors it encompasses. You can always use a larger conduit, which is basically the same as using a larger wire, if you want to. But you can't use EMT that's 'too small' because then you wouldn't be able to fit the wires in it.

Thanks sparky ! It makes sense now that you explain in that way !