Bonding subpanel to electrode

Status
Not open for further replies.
S

smallfish

Senior Member
Location
Detroit
A bonding jumper from the cold water pipe is run to a subpanel where this bonding jumper is connected to the terminal bar for the grounding conductors. The feeder equipment grounding conductor from the service panel is terminated to this bar as well.
The feeder neutral is isolated from this terminal in the subpanel.
Does the use of this bonding jumper dissipate fault current back to the system neutral thereby interfering with the opening of the OCPD on a fault?
If this is a violation to code, is there a section in the code that applies?
Thanks
 
smallfish said:
A bonding jumper from the cold water pipe is run to a subpanel where this bonding jumper is connected to the terminal bar for the grounding conductors. The feeder equipment grounding conductor from the service panel is terminated to this bar as well.
The feeder neutral is isolated from this terminal in the subpanel.
Does the use of this bonding jumper dissipate fault current back to the system neutral thereby interfering with the opening of the OCPD on a fault?
If this is a violation to code, is there a section in the code that applies?
Thanks
Click to expand...

First question: Is this subpanel in the same building as the main service?
 
Last edited:
smallfish said:
Yes, this subpanel is in the same building as the service main. The building is a single family dwelling.
Click to expand...

That bonding connection is not required at the sub panel.

Second question.

Is the Service bonded to the same pipe?
 
smallfish said:
A bonding jumper from the cold water pipe is run to a subpanel where this bonding jumper is connected to the terminal bar for the grounding conductors. The feeder equipment grounding conductor from the service panel is terminated to this bar as well.
The feeder neutral is isolated from this terminal in the subpanel.
Does the use of this bonding jumper dissipate fault current back to the system neutral thereby interfering with the opening of the OCPD on a fault?
If this is a violation to code, is there a section in the code that applies?
Thanks
Click to expand...


This is a code violation since this is the same building, the GEC is not to be used (or should not be used) to open the OCPD. 2005 NEC 250.36 (F) tells you where to connect the GEC. Only the EGC is used to open the ocpd, 250.4(5). Only time you can connect the egc and gec in this fashion is the main service or when you are in a SEPERATE building 250.32(B)(1)
 
This bonding jumper is connecting the water pipe to the EG bar in the subpanel. Same building or not how is this a violation?
 
brother said:
This is a code violation since this is the same building, the GEC is not to be used (or should not be used) to open the OCPD. 2005 NEC 250.36 (F) tells you where to connect the GEC. Only the EGC is used to open the ocpd, 250.4(5). Only time you can connect the egc and gec in this fashion is the main service or when you are in a SEPERATE building 250.32(B)(1)
Click to expand...

I am not sure you are correct. I understand that one does not need a gec at a sub panel but there is an egc present and I don't see where the code specifies that an gec can only be installed at a service or separate building.

Yes 250.32 requires it on a separate building but it does not prohibit it elsewhere.
 
Duplicate threads are annoying,.. But,..now that I read this post again I'm not sure what is being asked ... but 250.54 would allow for a sub panel to connect to a grounding electrode.

assuming 250.24 has been complied with
 
Last edited:
Dennis Alwon said:
I am not sure you are correct. I understand that one does not need a gec at a sub panel but there is an egc present and I don't see where the code specifies that an gec can only be installed at a service or separate building.

Yes 250.32 requires it on a separate building but it does not prohibit it elsewhere.
Click to expand...


Im not sure i understand what you are saying is not correct. I think you misread what i said. I was not saying that he 'needed' a gec just because its a 'sub panel', nor was I saying that the "gec can only be installed at separate building or service".I do not know where else one would want to install one, unless they had to.

I said the only time you can connect the egc and gec in this fashion (directly to each other was what i was referring to) is the main service or when you are in a SEPERATE building 250.32(B)(1). The gec is normally connected to the 'grounded'(neutral) conductor buss, and then the jumper is from the neutral buss to the egc terminal (the bonding) at the main service panel, Assuming this is not the 'seperate' building on this premise as the op had stated.
 
I see no violation with the OP, all the bonding jumper is doing is supplying the grounding/bonding connection that is required for the enclosure. The grounding and grounded conductors should be separate at this point as we all know.
 
I find that I have mixed emotions on this. The bonding jumper to the cold water pipe is obviously not needed since we have the eq. grounding condutor.
If the additional jumper was connected within 5 ft of water pipe entering the bulding, then I think we would be fine under 250.54.
Beyond the 5 ft, the pipe is no longer an electrode, so we are not adding an auxiliary grounding electrode, we are simply installing a ground to a water line. On the surface I see no problem, but someone more knowledgable might discuss possible current flow in the line.
 
smallfish said:
A bonding jumper from the cold water pipe is run to a subpanel where this bonding jumper is connected to the terminal bar for the grounding conductors. The feeder equipment grounding conductor from the service panel is terminated to this bar as well.
The feeder neutral is isolated from this terminal in the subpanel.
Click to expand...

What do the neutral conductors for the branch circuits connect to in the sub-panel? What is the feeder neutral connected to? Is there an isolated neutral terminal bar in this panel?

Branch circuit neutrals (grounded conductors) must be isolated from ground in this panel.

There is nothing wrong with bonding the EGC terminal bar to the cold water pipe.
 
I can't find a section that calls an underground water pipe a "supplemental" electrode. This fact suggests that other types of electrodes are intended to supplement this metal waterpipe. Metal water piping is supposed to be bonded as per 250.104(A). See (A)(1) where it allows that the metal waterpipe is bonded to the 1) service equipment enclosure, 2) the grounded conductor at the service, 3) the grounding electrode conductor where of sufficient size, or to one or more of the grounding electrodes used.

Supplementary grounding electrodes (other than water pipes which are not defined as "supplemental") may be connected to egc's as per 250.54.

Anybody agree.....or disagree? :)
 
semantics, to me.
as I read it, 10 ft of underground water pipe is an electrode, but more than 5 ft past it's entrance to the building is not considered an electrode.
If your service is bonded to it, as required, then if you decide to bond
some other grounded equipment to the pipe, then, to me, the water pipe would be a "supplemental" ground for that piece of equipment.
But, again, to me it's semantics. If someone wants to install such a line, I see no problem
 
barbeer said:
I see no violation with the OP, all the bonding jumper is doing is supplying the grounding/bonding connection that is required for the enclosure. The grounding and grounded conductors should be separate at this point as we all know.
Click to expand...
Did you read 2005 NEC 250.36(F) and rest of the articles i quoted. Remember the op said this was a SUBPANEL, not the Main service. Doing this is a code violation, and a GEC is not to be used to open an ocpd.
 
brother said:
Did you read 2005 NEC 250.36(F) and rest of the articles i quoted. Remember the op said this was a SUBPANEL, not the Main service. Doing this is a code violation, and a GEC is not to be used to open an ocpd.
Click to expand...

Brother-- I don't get it. The OP is saying he has a sub panel that has a 4 wire cable run to it. The neutral and grounding conductors are isolated from each other at this point. The op says there is a GEC that runs from the ground bar, not the neutral bar, of this sub panel and connects to the water pipe.

Where is the violation-- what am I missing? It definitely is not a necessary install but a violation , I think not.
 
smallfish said:
A bonding jumper from the cold water pipe is run to a subpanel where this bonding jumper is connected to the terminal bar for the grounding conductors. The feeder equipment grounding conductor from the service panel is terminated to this bar as well.
The feeder neutral is isolated from this terminal in the subpanel.
Does the use of this bonding jumper dissipate fault current back to the system neutral thereby interfering with the opening of the OCPD on a fault?
If this is a violation to code, is there a section in the code that applies?
Thanks
Click to expand...

Does the service equipment have a grounding electrode conductor that is directly bonded to the cold water pipe...?...or does the grounded conductor/grounding electrode conductor have to "hitch hike" on the equipment grounding conductor of the 4-wire cable thru the remote panelboard to eventually connect with the bonding conductor connecting to the cold water pipe? If the latter is the case, I think this is a huge violation.
 
wbalsam1 said:
Does the service equipment have a grounding electrode conductor that is directly bonded to the cold water pipe...?...or does the grounded conductor/grounding electrode conductor have to "hitch hike" on the equipment grounding conductor of the 4-wire cable thru the remote panelboard to eventually connect with the bonding conductor connecting to the cold water pipe? If the latter is the case, I think this is a huge violation.
Click to expand...

That's a good point. I was assuming that the gec was extra and that there was another gec at the main service. Apparently I could be mistaken yet again. :D
 
I read it the same way as Dennis ,.. there is nothing wrong with bonding the EGC at the sub panel to water pipe electrode ,.. the interior gas pipe the,..metal hot air ducts ,..the air lines,. the building steel ,..the metal waste pipes ,..bond it all baby the more the better

smallfish said:
A bonding jumper from the cold water pipe is run to a subpanel where this bonding jumper is connected to the terminal bar for the grounding conductors. The feeder equipment grounding conductor from the service panel is terminated to this bar as well.
The feeder neutral is isolated from this terminal in the subpanel.
Does the use of this bonding jumper dissipate fault current back to the system neutral thereby interfering with the opening of the OCPD on a fault?
If this is a violation to code, is there a section in the code that applies?
Thanks
Click to expand...
Not only will it not interfere it will provide a lower overall impedance under fault conditions ,...assuming a complete metal piping system In this case two paths are better than one.
 
Last edited:
Dennis Alwon said:
Brother-- I don't get it. The OP is saying he has a sub panel that has a 4 wire cable run to it. The neutral and grounding conductors are isolated from each other at this point. The op says there is a GEC that runs from the ground bar, not the neutral bar, of this sub panel and connects to the water pipe.

Where is the violation-- what am I missing? It definitely is not a necessary install but a violation , I think not.
Click to expand...


Ok, I ll quote the section,

NEC 2005 250.36(F) said:
Grounding Electode Conductor Location. The grounding electrode conductor SHALL be attatched at any point from the grounded side of the grounding impedance to the equipment grounding connection AT the SERVICE equipment or first disconnection means.
Click to expand...

It says shall be, not maybe, not in addition to, but shall be at the service. Remember the op said this was done at the 'sub panel' and this is in the 'same building' so this is not a service equipment or the 'first disconnection means'.


The Gec is for over voltages and lighting, why would you want to create another (parrallel) path for this lighting to follow (going to the subpanel with the additional voltage)???? this is ASSUMING that it was bonded at the service panel as well. It very well may not be, and that most definitely would be a violation. This is how i read this section anyway, especially the parrallel path for the overvoltage.
 
Status
Not open for further replies.
Top