Article 250 Grounding and Bonding Sticky

[mbrooke]

This is a nice reference:

https://www.inw-training.com/site/images/Documents/Grounding & Bonding Mind Map.pdf


I'm thinking Mike Could make something like this and have it posted here as a reference sticky.

 

[infinity]

Nice to have everything on one page. I would say that the MBJ in the service disconnect would need to be a wire or bus bar in order for the GEC to land on the EGC bus. If the MBJ is a green screw then the graphic is incorrect.

 

[Leigh Simpson]

This is a nice reference:

https://www.inw-training.com/site/images/Documents/Grounding & Bonding Mind Map.pdf


I'm thinking Mike Could make something like this and have it posted here as a reference sticky.

Table 250.66 would tell us to run a 1/0 copper to the water pipe, but this makes no sense still there is no conductive material. Also, bonding the hot - cold at the water heater makes no sense. But would you run to the gas piping? I am confused?

 

[Leigh Simpson]

Nice to have everything on one page. I would say that the MBJ in the service disconnect would need to be a wire or bus bar in order for the GEC to land on the EGC bus. If the MBJ is a green screw then the graphic is incorrect.

Table 250.66 would tell us to run a 1/0 copper to the water pipe, but this makes no sense still there is no conductive material. Also, bonding the hot - cold at the water heater makes no sense. But would you run to the gas piping? I am confused?

 

[mbrooke]

Nice to have everything on one page. I would say that the MBJ in the service disconnect would need to be a wire or bus bar in order for the GEC to land on the EGC bus. If the MBJ is a green screw then the graphic is incorrect.

Why would a green screw be a violation?

 

[infinity]

Why would a green screw be a violation?

The GEC is required to be connected to the neutral or grounded service conductor. If the MBJ is a wire or busbar then the GEC can be connected to the equipment grounding bus. A MBJ consisting of a strap or screw would require that the GEC is connected to the neutral. The graphic shows it connected to the EG bus which means that the MBJ cannot be a screw or strap.

250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).
(4) Main Bonding Jumper as Wire or Busbar. Where the main bonding jumper specified in 250.28 is a wire or busbar and is
installed from the grounded conductor terminal bar or bus to the equipment grounding terminal bar or bus in the service
equipment, the grounding electrode conductor shall be permitted to be connected to the equipment grounding terminal, bar, or bus to which the main bonding jumper is connected.

 

[mbrooke]

Right, but I'm not seeing anything that says the screw can not be green. To be fair I'm thinking of just the screw itself. You're right about the graphic, its not to code, but at the same time literally 50% of the prints I've seen show all the GECs on the ground bar.

 

[infinity]

Right, but I'm not seeing anything that says the screw can not be green. To be fair I'm thinking of just the screw itself.

If the screw is used as the MBJ it is required to be green. If the GEC lands on the EGC bus the screw cannot be used as the MBJ.

250.28(B) Construction. Where a main bonding jumper or a system bonding jumper is a screw only, the screw shall be identified with a green finish that shall be visible with the screw installed.

 

[mbrooke]

Agree.

Anyone know why the GECs must land on the neutral bar and not the ground bar? Seems arbitrary.

 

[Joe.B]

Love this, I saved a copy for future reference. Doesn't specify what version of NEC this is compliant with, I'm assuming that they intend this to be compliant with current version? Or any version up to 2020? Regardless it's a great quick reference.

 

[mbrooke]

Love this, I saved a copy for future reference. Doesn't specify what version of NEC this is compliant with, I'm assuming that they intend this to be compliant with current version? Or any version up to 2020? Regardless it's a great quick reference.

Not sure to be honest.

I'm going to push Mike to start making these, he is losing out IMO.

 

[LarryFine]

Anyone know why the GECs must land on the neutral bar and not the ground bar? Seems arbitrary.

My theory: Everything connects to the source neutral, not to the grounding system. The premises grounding system begins where the electrode system terminates.

The premises grounding system is one of the systems that connects to the neutral, so other systems should also connect to the neutral, not one of the other systems.

I almost understand me.

 

[mbrooke]

My theory: Everything connects to the source neutral, not to the grounding system. The premises grounding system begins where the electrode system terminates.

The premises grounding system is one of the systems that connects to the neutral, so other systems should also connect to the neutral, not one of the other systems.

I almost understand me.

Right... until you lose the MBJ... one less risk I guess?