How To Tap Off Common GEC

[Jerramundi]

I'm working on correcting an existing installation right now that will require me to run a common GEC for 200A AWG Overhead Service Conductors and tap off it 3 times to 3 individual 100A Main Breaker Panels.

Not a typical installation for me, so any ideas would help. Right now I'm thinking of running a common GEC from the water main to j-boxes below each panel and using a c-clamp in each j-box to tap off it for each respective panel.

Seems to me this would be the more cost effective solution as opposed to running 3 separate GECs for each 100A panel...

Thoughts? Ideas?

 

[tom baker]

A copper busbar is an ideal solution for this.

 

[Jerramundi]

A copper busbar is an ideal solution for this.

I would agree if it wasn't a residential two family home. I don't think I've ever seen a copper bus bar in a residential setting.
I need something more cost effective than spending $100+ on a copper bus bar for 1 common GEC and 3 taps.

 

[SSDriver]

I would agree if it wasn't a residential two family home. I don't think I've ever seen a copper bus bar in a residential setting.
I need something more cost effective than spending $100+ on a copper bus bar for 1 common GEC and 3 taps.

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

2" x 6" x .25. $17.31, drill and tap as needed.

Or just use split bolts.

Or H taps.

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[Jerramundi]

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

2" x 6" x .25. $17.31, drill and tap as needed.

Gotta be UL listed as grounding and bonding equipment.

 

[SSDriver]

Gotta be UL listed as grounding and bonding equipment.

The bus bar does not. The connectors do. The copper bus bar just has to be 2" wide x 1/4" thick and long enough to accommodate the connections.

See 250.64 D1 (3)

1) Exothermic welding.
(2) Connectors listed as grounding and bonding equipment.
(3) Connections to an aluminum or copper busbar not less
than 6 mm thick × 50 mm wide (1∕4 in. thick × 2 in. wide)
and of suficient length to accommodate the number of
terminations necessary for the installation. The busbar
shall be securely fastened and shall be installed in an
accessible location. Connections shall be made by a listed connector or by the exothermic welding process. If alumi‐
num busbars are used, the installation shall comply with
250.64(A).

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[LarryFine]

A separate electrode conductor sized for 100a from each disconnect may attach to a single common electrode conductor sized for 200a (or would it be 300a?), and those attachments can even be split bolts. The common conductor must be unspliced or irreversibly spliced.

 

[infinity]

I would use a split bolt. Cheap and easy.

 

[Jerramundi]

The bus bar does not. The connectors do. The copper bus bar just has to be 2" wide x 1/4" thick and long enough to accommodate the connections.

Interesting proposition. I appreciate the suggestion but I don't have the stones to attempt that, not yet anyway. I would argue that the NEC referring to it as a "bus bar" would mean it would have to listed as such, which is not the same thing as just buying a piece of copper of the same dimensions.

I also worry that there may be a section of code that requires all "grounding and bonding materials" to be listed explicitly for "grounding and bonding" purposes that I can't recall at this exact moment.

I actually have family that worked for and even retired from McMaster-Carr here in IL. So I'm familiar with the company. I think there's a catalog lying around here somewhere. Anyway, appreciate the suggestion, but I'm not ballsy enough to just buy a piece of copper of the same dimensions.

 

[Jerramundi]

A separate electrode conductor sized for 100a from each disconnect may attach to a single common electrode conductor sized for 200a (or would it be 300a?), and those attachments can even be split bolts. The common conductor must be unspliced or irreversibly spliced.

As far as I'm aware, I have 2 options:

Option #1: Run separate GECs from each panel to the water main sized from 250.66 according to the ungrounded service entrance conductors in each panel (100A), or...

Option #2: Run a common GEC from the panel area to the water main sized from 250.66 according to the size of the ungrounded overhead service conductors and tap off it for each individual panel.

Option #1 seems more complicated and expensive. In my case, I would have to run 2 additional lengths of 50+ ft of GEC (1 panel already has a GEC to the water main, 2 do not, all 3 are main breaker panels) and I'm not sure if I could fit all 3 in the existing conduit or how to bond all 3 at the ends of a single conduit raceway, if even possible. I would imagine each GEC should have it's own raceway and that pretty much x's that idea.

I'm looking at Option #2 in which I which replace the existing GEC for a resized one for the overhead service conductors and tap off it 3 times. The question I'm asking is about methodology. Right now I'm looking at running the common GEC to junction boxes below each panel and tapping off it with a C-Clamp.

 

[Jerramundi]

I would use a split bolt. Cheap and easy.

I've considered that... but something about a split bolt floating in a junction box below each panel just seems off to me, even if it is code approved. The C-Clamp seems cleaner. Thoughts?

 

[roger]

I would argue that the NEC referring to it as a "bus bar" would mean it would have to listed as such, which is not the same thing as just buying a piece of copper of the same dimensions.

Nope, if the NEC required a copper busbar be listed for the purpose it would specifically state it.

90.7 Examination of Equipment for Safety. For specific
items of equipment and materials referred to in this Code,

For some examples look at all article sections 3XX.6 starting at 340 through 362.

Roger

 

[SSDriver]

Interesting proposition. I appreciate the suggestion but I don't have the stones to attempt that, not yet anyway. I would argue that the NEC referring to it as a "bus bar" would mean it would have to listed as such, which is not the same thing as just buying a piece of copper of the same dimensions.

I also worry that there may be a section of code that requires all "grounding and bonding materials" to be listed explicitly for "grounding and bonding" purposes that I can't recall at this exact moment.

I actually have family that worked for and even retired from McMaster-Carr here in IL. So I'm familiar with the company. I think there's a catalog lying around here somewhere. Anyway, appreciate the suggestion, but I'm not ballsy enough to just buy a piece of copper of the same dimensions.

Done hundreds of them and passed inspection every time. It is common practice.

If its required to be listed NEC will state it. How would you bolt lugs together or to bus bars? I've never been able to buy listed and approved bolts/nuts. Why? Because it is not required.

Do what ever is comfortable to you. Also split bolts on a GEC is super common for this type of application, especially for residential. I use bus bars a lot because 95% of my work is commercial. I do buy the listed ones when I have a bunch of panels/equipment that need to connect to it , and then it saves time.

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[Jerramundi]

Nope, if the NEC required a copper busbar be listed for the purpose it would specifically state it.

You and SSDriver may correct. Honestly, I'm not sure. Something about it seems, well iffy to me. Perhaps because I've never done a job to a scale that would require a copper bus bar. I've worked on large scale commercial projects for other contractors, but I was always in the individual units running the branch circuits.

It's a relevant suggestion to my OP and I am thankful for the input. However, it's not one, that for my purposes, is worth the debate. I've never seen a copper bus bar utilized in residential. If this were a large scale commercial project, I would give this suggestion more consideration., but my current project is just a two family building.

 

[Jerramundi]

Done hundreds of them and passed inspection every time. It is common practice...

...Also split bolts on a GEC is super common for this type of application, especially for residential.

Maybe so. As I said in response to Roger, you guys may be correct. I don't typically bid large commercial projects so it's entirely possible this is beyond my regular scope of experience.

I've considered the split bolt option. If the GEC were being buried, a split bolt would feel more "correct." However, something about a split bolt floating in a junction box below each panel for tapping purposes seems weird.

I'm throwing together a quick sketch of what I'm thinking to share with you all... hopefully it will help convey where I'm not 100% confident.

 

[Jerramundi]

How does this look to everyone? Thoughts? Suggestions?

Note #1: The "Common GEC" will be sized according to 250.66 according to the AWG of the Overhead Service Conductors (outside)
Note #2: The "GEC Taps" will be sized according to 250.66 according to the AWG of the Ungrounded Service Entrance Conductors in each
respective panel (100A)

 

[SSDriver]

How does this look to everyone? Thoughts? Suggestions?

Note #1: The "Common GEC" will be sized according to 250.66 according to the AWG of the Overhead Service Conductors (outside)
Note #2: The "GEC Taps" will be sized according to 250.66 according to the AWG of the Ungrounded Service Entrance Conductors in each
respective panel (100A)

View attachment 2552773

That should be fine just keep in mind that your water pipe electrode must be supplemented by another electrode. See 250.53

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[Jerramundi]

That should be fine just keep in mind that your water pipe electrode must be supplemented by another electrode. See 250.53

Yes, there is an existing second GEC outside on the meter bank running to ground rods.

 

[Jerramundi]

That should be fine just keep in mind that your water pipe electrode must be supplemented by another electrode. See 250.53

Any suggestions other than a "C-Clamp?" I didn't realize this $2.00 clamp would require a $2,000.00 hydraulic hand tool to install, haha.
I know you said split bolt, but is this okay in a junction box? Doesn't the connector have to be "irreversible?"

I don't see anything in 250.64(C)(1-4) that allows for "mechanical" connectors.

250.64(C)(1) Splicing of the wire type grounding electrode conductor shall be permitted only by (1) irreversible compression type connectors listed as grounding and bonding equipment or (2) exothermic welding process.

 

[SSDriver]

Any suggestions other than a "C-Clamp?" I didn't realize this $2.00 clamp would require a $2,000.00 hydraulic hand tool to install, haha.
I know you said split bolt, but is this okay in a junction box? Doesn't the connector have to be "irreversible?"

I don't see anything in 250.64(C)(1-4) that allows for "mechanical" connectors.

250.64(C)(1) Splicing of the wire type grounding electrode conductor shall be permitted only by (1) irreversible compression type connectors listed as grounding and bonding equipment or (2) exothermic welding process.

Most people refer to them as C taps. You can get a crimper for a few hundred that would work. Cost and needing a specific die are why a lot of people on residential or even some commercial use split bolts. No special tools required.

You are not splicing the grounding electrode conductor, the larger conductor is considered the GEC. The smaller wires are taps/jumpers and are not required to have irreversible crimps. Yes the connection in a Junction Box is perfectly fine with split bolts. Look up the definitions for all of these items in article 100. It will really help you figure out how to read/understand the NEC better. Just make sure you use 3 separate split bolts as most split bolts are only listed for 2 or 3 wires only. Also make sure the range on the split bolt is correct and they are listed for bonding and grounding.

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