Main Disconnect Switching the EGC?

I am finishing schematics for my senior engineer. The schematic he sent over has a 3 pole disconnect switch the equipment grounding conductor (Ground) is this a good idea?


See screen shot attached

No !

I have never seen that, you might ask the engineer why, maybe he knows something we don't??

Hi, this looks like it could be from a machine that needs all power and grounding disconnected at the same time--some gasoline dispensers are wired this way. It appears to be a 120 VAC circuit from the plug shown. It is disconnecting the neutral, and it's using a 2-pole breaker, which seems not right because the current carrying conductor is what would make the breaker trip, not the neutral.

In the 2014 NEC, the only reference I can find for switching equipment grounds is in Section 250.124 (B). And that mentions a premises, not industrial equipment.

For the record this is just a little table top machine with an electric slide and some phenumatic cylinders. It is not for a hazardous location, it will just go in a nice clean factory assembly room, where they snap and screw together plastic parts.



Technically the 2 pole breaker is actually a 1 pole breaker with a linked disconnect for the neutral. He just has it depicted as a 2 pole breaker. It's a S201-C16NA.

damica1 said:

I have never seen that, you might ask the engineer why, maybe he knows something we don't??

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He never gives me straight answers on things. Some times I think he just does things because he feels like it. Which is fine on some things, not on others.

He just told me it was safer to put a 208VAC 3P 15A Disconnect on a din rail in the panel instead of mounted through the panel door, but he is the one that uses the exact same 3P disconnect to switch 15A 120VAC line, Neutral and ground, on the panel door.... I asked him how is 208V and more dangerous on the panel door than 120V is? his respond was "well that is just the way we have always done it here"


This is why I come and ask you guys things...

Having the disconnect open the ground would never pass code anywhere in the US.
The system ground must not be interrupted .
But in this case the panel is connected through a portable cable with a plug this would be considered the disconnect. So on this panel the 3 pole disconnect would not be necessary and it would pass code because of the plug. I have seen system where the disconnect braked the neutral conductor as well as the hot side more on marine systems then land based that is fine and up to code.
this panel would most likely *** because of the plug disconnect

Tread lightly Colonel, but keep your eyes and ears open

Two conflicting pieces of information in your posts:
1. "Senior Engineer"
2. "That's the way we've done it for years"

Just because the person is older than you does not make them a senior engineer. It merely makes them older than you. What are their true credentials?

Item 2 Is the biggest red flag that engineering to current Codes and Standards assuredly are not in place. A legitimate engineer will be rotating through continued education regarding updated codes and standards.


Don't challenge them, but alternatively, use Google and this site to learn NFPA70 and NFPA 79 yourself. Both of these have changed quite a bit since I began 30 years ago. I am required to re-educate, and PROVE up-to-date to renew my license.


Again, don't challenge, learn as much as you can on your own.


I don't think interrupting the neutral (Grounded conductor) is problematic, as it is linked and simultaneously with the phase conductor..... But I would need a sound, purposeful, and cited engineering reason to switch the equipment grounding conductor.

I hope you/he realizes that the circuit breaker referenced in that link is not allowed to be used as branch circuit protection, meaning that there must be a BCP device ahead of it.

You can switch the neutral so long as it is done along with the hot via mechanical linkage. Switching the ground is pointless in this situation, the plug and receptacle are basically doing the same thing if you think about it. So I don’t see why that would be verboten here. Hard wired though, I agree with the others.

Plastic said:

Two conflicting pieces of information in your posts:
1. "Senior Engineer"
2. "That's the way we've done it for years"

Just because the person is older than you does not make them a senior engineer. It merely makes them older than you. What are their true credentials?

Item 2 Is the biggest red flag that engineering to current Codes and Standards assuredly are not in place. A legitimate engineer will be rotating through continued education regarding updated codes and standards.


Don't challenge them, but alternatively, use Google and this site to learn NFPA70 and NFPA 79 yourself. Both of these have changed quite a bit since I began 30 years ago. I am required to re-educate, and PROVE up-to-date to renew my license.

Click to expand...

He is the "Senior" because our owner says he is. He technically has 10 years experience on me, thought I find that hard to believe given his knowledge level. The owner thinks he walks on water. My opinion differs a little from that... (and if you care he is only 6 years older than me).



Neither of us are Degree-ed engineers. He has no formal training at all, just on the job learn as you go. I have an AAS in Electrical Technology and an AAS in Electro-Mechanical Maintenance, (and if you care a AS in Computer Science which is helpful on the programming side). So I have at least been familiarized with most of these concepts from the maintenance side. He's really good and fast at making things work, but has no inkling of how they should be done, or why. Abstract concepts are nonsense in his eyes. (As far as I can tell)


I on the other hand am always trying to learn new concepts and theories and apply them to my daily job. So I already plan on taking your advice.


As for NFPA70 I was quite familiar with it when I was in school, it was a major part of a lot of my classes. NFPA79 not so much thought I took a machine controls class and 3 PLCs Classes it was just briefly touched on.

Plastic said:

Again, don't challenge, learn as much as you can on your own.


I don't think interrupting the neutral (Grounded conductor) is problematic, as it is linked and simultaneously with the phase conductor..... But I would need a sound, purposeful, and cited engineering reason to switch the equipment grounding conductor.

Click to expand...

Yes interrupting the neutral is not really concerning to me.

jraef said:

I hope you/he realizes that the circuit breaker referenced in that link is not allowed to be used as branch circuit protection, meaning that there must be a BCP device ahead of it.

You can switch the neutral so long as it is done along with the hot via mechanical linkage. Switching the ground is pointless in this situation, the plug and receptacle are basically doing the same thing if you think about it. So I don’t see why that would be verboten here. Hard wired though, I agree with the others.

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I had not, that model is required by our customer so as part of their standard machine spec. It is not the actual main branch circuit protection. There is a 15A or a 20A feeding the plug that this plugs in to.


This Eaton breaker would be correct? FAZ-C15-1-NA-SP