Would you (an inspector) call this subject to abuse? GEC

[richwaskowitz]

OK, please bear with me. I wasn't getting the response I was looking for in an earlier post so I thought I might rephrase it. I understand 250.64 B. I am asking if running a bare or even insulated #6 or larger GEC along the bottoms of the floor joists in a basement can be OK sometimes or never. What I want to know is, would this be rejected every time or is it just another "depends on the inspector" issues. I am trying to understand why an NM cable of a certain gauge is OK but a GEC is not??? What damage is really likely to occur to a GEC that could actually sever the wire where it would seem that an NM with actual energized and current carrying wires in it would be a lot more likely to cause shock or fire?

 

[infinity]

Here's the wording from the NEC:

(B) Securing and Protection Against Physical Damage.
Where exposed, a grounding electrode conductor or its enclo-
sure shall be securely fastened to the surface on which it is
carried. Grounding electrode conductors shall be permitted to
be installed on or through framing members. A 4 AWG or
larger copper or aluminum grounding electrode conductor
shall be protected if exposed to physical damage. A 6 AWG
grounding electrode conductor that is free from exposure to
physical damage shall be permitted to be run along the surface
of the building construction without metal covering or protec-
tion if it is securely fastened to the construction; otherwise, it
shall be protected in rigid metal conduit RMC, intermediate
metal conduit (IMC), rigid polyvinyl chloride conduit (PVC),
reinforced thermosetting resin conduit (RTRC), electrical me-
tallic tubing EMT, or cable armor. Grounding electrode con-
ductors smaller than 6 AWG shall be protected in (RMC),
IMC, PVC, RTRC, (EMT), or cable armor. Grounding elec-
trode conductors and grounding electrode bonding jumpers
shall not be required to comply with 300.5.

There is two separate issue, for the #6 you need to follow the surface of the construction. For #4 or larger you need to protect it if exposed to physical damage. IMO the #4 can be stapled directly to the underside of the joists without protection just like large NM cable or AC/MC cables.

 

[jap]

Here's the wording from the NEC:



There is two separate issue, for the #6 you need to follow the surface of the construction. For #4 or larger you need to protect it if exposed to physical damage. IMO the #4 can be stapled directly to the underside of the joists without protection just like large NM cable or AC/MC cables.

Which for the #6, some consider the surface of the construction eliminates being able the cross the floor joists at 90 degrees since there is a 16 or 24 inch gap between them.

JAP>

 

[jaggedben]

"Exposed to physical damage" is not defined so it "depends on the inspector".

 

[JFletcher]

just my 2cp: in a basement, the issue is people stacking junk between the joists on top of the wiring, or hanging stuff from it. If you use running boards (or, accepted here, on the band board), you can run smaller wires/cables across joists because there is then no practical way of using the wire/cable to support anything. Running parallel to joists/beams doesnt require running boards.

I'm guessing the joists run perpendicular to the way you need to run your ground, and you're looking at drilling 35-50 holes (75' with 16-24" OC framing) if you have to go thru them all. It's probably easier to follow the band all the way around and use a bit more wire than carrying down 10 8' running boards and associated hardware or drilling that many holes in a reasonably straight line.

Interesting to note that the VA IRC makes a distinction between basements and crawlspaces; the latter you can staple NM of any size to the bottom of joists, presumably because people aren't crawling in crawlspaces and stuffing junk up between the joists on top of the wiring.

 

[mgookin]

I'm in the "depends on the inspector" camp. You can argue it with him until the cows come home.

Is the job done and red tagged?

 

[jap]

just my 2cp: in a basement, the issue is people stacking junk between the joists on top of the wiring, or hanging stuff from it. If you use running boards (or, accepted here, on the band board), you can run smaller wires/cables across joists because there is then no practical way of using the wire/cable to support anything. Running parallel to joists/beams doesnt require running boards.

I'm guessing the joists run perpendicular to the way you need to run your ground, and you're looking at drilling 35-50 holes (75' with 16-24" OC framing) if you have to go thru them all. It's probably easier to follow the band all the way around and use a bit more wire than carrying down 10 8' running boards and associated hardware or drilling that many holes in a reasonably straight line.

Interesting to note that the VA IRC makes a distinction between basements and crawlspaces; the latter you can staple NM of any size to the bottom of joists, presumably because people aren't crawling in crawlspaces and stuffing junk up between the joists on top of the wiring.

Well put.

JAP>

 

[ActionDave]

....Interesting to note that the VA IRC makes a distinction between basements and crawlspaces; the latter you can staple NM of any size to the bottom of joists, presumably because people aren't crawling in crawlspaces and stuffing junk up between the joists on top of the wiring.

Interesting to note that the geniuses at the NEC can't make that distinction.

 

[richwaskowitz]

No this is not already installed. I'm just trying to educate myself by getting others' experiences. I guess I jut don't see how a #2 aluminum single conductor is more at risk than an 8-3 Romex. I don't understand what kind of abuse is being anticipated here. What would be the worst thing that might happen if you whacked the#2 with with a hammer or hung clothes from it?

 

[kwired]

Which for the #6, some consider the surface of the construction eliminates being able the cross the floor joists at 90 degrees since there is a 16 or 24 inch gap between them.

JAP>

Now drill the joists and pull same conductor through the holes - they magically are no longer subject to the same abuse. Same with your smaller size NM cables.:blink:

I'm in the "depends on the inspector" camp. You can argue it with him until the cows come home.

Is the job done and red tagged?

Yes, to the first part.

 

[jap]

Now drill the joists and pull same conductor through the holes - they magically are no longer subject to the same abuse. Same with your smaller size NM cables.:blink:

Yes, to the first part.

I never thought it had so much to do with abuse as much as it did the stress put on the smaller conductors that would need to be pulled tight before stapling them to the bottom of the joists.

At least that's the only reason I can come up with for having to drill the holes which I don't do.

I'll put up runners if I have to before I drill a holes in a perfectly sound floor joist.


JAP>

 

[jaggedben]

No this is not already installed. I'm just trying to educate myself by getting others' experiences. I guess I jut don't see how a #2 aluminum single conductor is more at risk than an 8-3 Romex.

It's not that it's at more risk of damage, it's that it's a more critical component of the system and thus requires more protection. If a single romex circuit gets damaged, the danger is limited to that circuit and likely to be noticed if the circuit stops functioning. If the GEC gets disconnected, then every circuit in the building may be susceptible to unstable voltage as well as unsafe voltage to ground, but the danger may not be noticed until someone or something gets damaged.

(That, at least, is the theory.)

 

[jap]

It's not that it's at more risk of damage, it's that it's a more critical component of the system and thus requires more protection. If a single romex circuit gets damaged, the danger is limited to that circuit and likely to be noticed if the circuit stops functioning. If the GEC gets disconnected, then every circuit in the building may be susceptible to unstable voltage as well as unsafe voltage to ground, but the danger may not be noticed until someone or something gets damaged.

(That, at least, is the theory.)

I would think unstable voltages to the whole system would be much more noticeable than a single branch circuit that may not be working.
Generally the bonding done where a #6 is used across floorjoist to get somewhere is just that, not so much to stabilize the voltage like at the service Transfomer.
If a #6 bonding jumper was to come loose from a water pipe I doubt you'd ever see a fluctuation of system voltage.


JAP>

 

[infinity]

No this is not already installed. I'm just trying to educate myself by getting others' experiences. I guess I jut don't see how a #2 aluminum single conductor is more at risk than an 8-3 Romex. I don't understand what kind of abuse is being anticipated here. What would be the worst thing that might happen if you whacked the#2 with with a hammer or hung clothes from it?

IMO nothing will happen.

 

[kwired]

It's not that it's at more risk of damage, it's that it's a more critical component of the system and thus requires more protection. If a single romex circuit gets damaged, the danger is limited to that circuit and likely to be noticed if the circuit stops functioning. If the GEC gets disconnected, then every circuit in the building may be susceptible to unstable voltage as well as unsafe voltage to ground, but the danger may not be noticed until someone or something gets damaged.

(That, at least, is the theory.)

Then there are those of us who think they put to much emphasis on the importance of grounding electrode systems, especially when connected to utility power where there is already a huge electrode system.

 

[jap]

Then there are those of us who think they put to much emphasis on the importance of grounding electrode systems, especially when connected to utility power where there is already a huge electrode system.

I would think it would have a lot to do with where the Lightning decides to hit.

JAP>

 

[jaggedben]

I would think unstable voltages to the whole system would be much more noticeable than a single branch circuit that may not be working.
Generally the bonding done where a #6 is used across floorjoist to get somewhere is just that, not so much to stabilize the voltage like at the service Transfomer.
If a #6 bonding jumper was to come loose from a water pipe I doubt you'd ever see a fluctuation of system voltage.


JAP>

Then there are those of us who think they put to much emphasis on the importance of grounding electrode systems, especially when connected to utility power where there is already a huge electrode system.

Yes, well, no real arguments there. See my last parenthetical sentence. I was just trying to explain that historically the code makers have had a strong bias towards keeping grounded systems grounded, and thus provided extra rules for the GEC.

I agree that unstable voltages are more likely to be noticed across the system l, but what I said was that something or someone is more likely to get damaged. As in, shocked by parts that should be grounded but aren't, or fried by inappropriate voltage. I stand by that, actually.

 

[iwire]

I guess I jut don't see how a #2 aluminum single conductor is more at risk than an 8-3 Romex.

If the inspector decides the 8-3 is subject to damage you can't run that under the joists either.

Again it's an inspector call.

 

[kwired]

I would think it would have a lot to do with where the Lightning decides to hit.

JAP>

And if it even makes it's way to the electrical system.

Direct hit to a structure, a grounding electrode may change how current flows in the event, you still will have some likely significant damage.

Surge coming in on the supply line because of a nearby strike, it may actually help you out some. IMO that is about all a GES is useful for on a utility supplied system, or similar event involving higher voltage line contacting a lower voltage line. There may still be some damages but it may help minimize it.

 

[jap]

And if it even makes it's way to the electrical system.

Direct hit to a structure, a grounding electrode may change how current flows in the event, you still will have some likely significant damage.

Surge coming in on the supply line because of a nearby strike, it may actually help you out some. IMO that is about all a GES is useful for on a utility supplied system, or similar event involving higher voltage line contacting a lower voltage line. There may still be some damages but it may help minimize it.

Surges from nearby lightning strikes do actually help out.
That's why I never get on the Treadmill during a storm.
Not that its dangerous, it's just that every time lightning hits close, the surge speeds up the motor and makes me have to walk faster.
I like to get on it when the AC is on, my wife is cooking something in the oven and my kid is drying his hair in the bathroom with the Heat/fan/light on.
It's much easier to keep the pace that way.

JAP>