SDS Grounding/Bonding.. Ground Loop?

[electrofelon]

Interesting point of contention. I suppose there are two GEC's, but are they both not supply side connections? I believe there is an explicit section of code that prevents load side neutral to ground connections precisely because there already exists a supply side connection (or connections).

First we have to be careful with terminology here and what we mean by "ground". There is a neutral/grounded conductor to earth/dirt connection, such as a GEC which must be somewhere between the service point and the service disconnect. Then there is connecting a grounded conductor to equipment somewhere on the load side. See 250.24(A)(5) and 250.142

 

[Jerramundi]

First we have to be careful with terminology here and what we mean by "ground". There is a neutral/grounded conductor to earth/dirt connection, such as a GEC which must be somewhere between the service point and the service disconnect. Then there is connecting a grounded conductor to equipment somewhere on the load side. See 250.24(A)(5) and 250.142

Interesting subsequent question... Where do you consider the beginning of the "load side" neutral to be at the panel since there is no disconnect clearly identifying a separation between the "supply side" and the "load side" like there is with the ungrounded conductors.. ?? That is unless you consider the neutral lug to be the point of disconnect... but that would make the bus bar "load side" and challenge the idea of connecting a GEC there.

I've always considered that main neutral lug + bus bar to be "the supply side" and the white wires themselves "coming back" from the respective loads to be the "load side."

Ahh relativity, fun isn't it?

 

[don_resqcapt19]

Interesting subsequent question... Where do you consider the beginning of the "load side" neutral to be at the panel since there is no disconnect clearly identifying a separation between the "supply side" and the "load side" like there is with the ungrounded conductors.. ?? That is unless you consider the neutral lug to be the point of disconnect... but that would make the bus bar "load side" and challenge the idea of connecting a GEC there.

I've always considered that main neutral lug + bus bar to be "the supply side" and the white wires themselves "coming back" from the respective loads to be the "load side."

Ahh relativity, fun isn't it?

The beginning of the load side is the location of the main or system bonding jumper which ever applies. No additional neutral to earth connections are permitted down stream of the enclosure where the main or system bonding jumper it located.

 

[Jerramundi]

The beginning of the load side is the location of the main or system bonding jumper which ever applies. No additional neutral to earth connections are permitted down stream of the enclosure where the main or system bonding jumper it located.

Already clear on the "no neutral to Earth connections downstream of the enclosure" part... I'm just toying with the terminology of "supply side/load side" as it pertains to this rule and the components of a panel.

Because if we consider the neutral bus itself "load side," then we would be in violation of the "no load side neutral to earth connections" rule when we land our GEC to the water main there... which is why I've suggested that the neutral bus in the panel be considered "supply side," but the individual branch circuit neutrals coming to the bus bar be considered "load side."

Perhaps this is how it's already done. I'm just saying this is how I've always thought about it in order to make sense of things.

I'm kind of working backwards logically speaking, but it's the only way to make sense of (1) the standard practice of landing our water main GEC on the neutral bus bar... in conjunction with (2) the restriction against "load side" neutral to Earth connections.

 

[electrofelon]

Already clear on the "no neutral to Earth connections downstream of the enclosure" part... I'm just toying with the terminology of "supply side/load side" as it pertains to this rule and the components of a panel.

Because if we consider the neutral bus itself "load side," then we would be in violation of the "no load side neutral to earth connections" rule when we land our GEC to the water main there... which is why I've suggested that the neutral bus in the panel be considered "supply side," but the individual branch circuit neutrals coming to the bus bar be considered "load side."

Perhaps this is how it's already done. I'm just saying this is how I've always thought about it in order to make sense of things.

I'm kind of working backwards logically speaking, but it's the only way to make sense of (1) the standard practice of landing our water main GEC on the neutral bus bar... in conjunction with (2) the restriction against "load side" neutral to Earth connections.

Take a look at 250.24(A)(1) "....to, including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means..."

 

[Jerramundi]

Take a look at 250.24(A)(1) "....to, including the terminal or bus to which the grounded service conductor is connected at the service disconnecting means..."

Oh yea, there's not a doubt in my mind that this, that is, connecting the GEC to the neutral bus, is allowable. I'm just curious about the "supply side" and "load side" designations as it pertains to this rule.

This particular code reference clearly states that this connection is allowable, but doesn't really clarify whether the neutral bus itself is considered "supply side" or "load side."

It's the latter 250.24(A)(5) Load Side Grounding Connections that makes this debate interesting to me, although not really in the best interesting of efficiency. The code says you can land the GEC on the neutral bus, so what does it matter if the neutral bus is "supply side" or "load side." "Just do it and be done" would be the conventional response. I'm just a curious cat and enjoy these kinds of intellectual debates.

It can get tricky because the "load side" of the overhead service conductors is still the "supply the side" of the overall system, which is why I made that joke about relativity being so much fun.

 

[LarryFine]

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Oh yea, there's not a doubt in my mind that this, that is, connecting the GEC to the neutral bus, is allowable. I'm just curious about the "supply side" and "load side" designations as it pertains to this rule.

I believe it's in reference to the main disconnecting means and/or its enclosure.

 

[Jerramundi]

It seems to me, that the need to explicitly allow this connection to the neutral bus in 250.24(A)(1) and the latter 250.24(A)(5) that states "a grounded conductor shall not be connected... on the load side of the service disconnecting means... except as otherwise permitted in this article" would mean the neutral bus itself is in fact "load side," but there are exceptions in the code which allow this connection.

I've always considered the neutral bus itself "supply side" to make sense of the fact that we land a GEC there, but I may be wrong. I'm not debating whether or not it is allowable to land a GEC here, just the "supply side" and "load side" designations.