Grounding Electrode

[mjf]

Single family residential.

Anything prohibiting driving a grounding electrode within the footprint of the dwelling?

For instance, into the dirt floor of the basement.

Just re-read parts of Article 250 I thought might apply and didn't find anything (but I can be blind sometimes).

 

[Dennis Alwon]

I don't see anything in the NEC prohibiting the rod from being in the basement. It may even be better in the sense that the rod is deeper in the earth where they may be more moisture

 

[mwm1752]

The only remote reason it would not be allowed

250.68 Grounding Electrode Conductor and Bonding Jumper Connection to Grounding Electrodes
(A) Accessibility. All mechanical elements used to terminate a grounding electrode conductor or bonding jumper to a grounding electrode shall be accessible.

There are exceptions -- do you mean crawlspace? usually a basement can be occcupied and have some sort of floor other than dirt.

 

[GlennG]

By me the utility company wants to see the ground rod somewhere within sight from the meter when they inspect the outside of the service.

 

[kwired]

The only remote reason it would not be allowed

250.68 Grounding Electrode Conductor and Bonding Jumper Connection to Grounding Electrodes
(A) Accessibility. All mechanical elements used to terminate a grounding electrode conductor or bonding jumper to a grounding electrode shall be accessible.

There are exceptions -- do you mean crawlspace? usually a basement can be occcupied and have some sort of floor other than dirt.

You said there are exceptions - if OP is talking ground rod (which I believe he is) then exception 1 applies.

Exception No. 1: An encased or buried connection to a concrete-encased, driven, or buried grounding electrode shall not be required to be accessible.

 

[Dennis Alwon]

The only remote reason it would not be allowed

250.68 Grounding Electrode Conductor and Bonding Jumper Connection to Grounding Electrodes
(A) Accessibility. All mechanical elements used to terminate a grounding electrode conductor or bonding jumper to a grounding electrode shall be accessible.

There are exceptions -- do you mean crawlspace? usually a basement can be occcupied and have some sort of floor other than dirt.

Many basements are dirt and not really habitable. Of course one could pour a slab some day but there would be accessibility with a rod driven in the dirt.

 

[kwired]

Many basements are dirt and not really habitable. Of course one could pour a slab some day but there would be accessibility with a rod driven in the dirt.

see exception 1, connection to a ground rod does not have to be accessible.

We often see sidewalks, driveways etc. installed over top of ground rods when they are "outdoors" - exception 1 allows this.

 

[mwm1752]

Yes , covering the electrode connection with concrete is valid
Denis here is the IBC definition: FYI the definition for story include finished floor surface.
BASEMENT. A storythat is not a storyabovegradeplane (see "Story above grade plane" in Section 202).
STORY ABOVE GRADE PLANE. Any story having its finished floor surface entirely above grade plane, or in which the
finished surface of the floor next above is:
1. More than 6 feet (1829 mm) above grade plane; or
2. More than 12 feet (3658 mm) above the finished ground
level at any point.
Still sounds like a crawlspace the OP describes.IMO With concrete floor we might have a basement.

 

[Dennis Alwon]

Yes , covering the electrode connection with concrete is valid
Denis here is the IBC definition: FYI the definition for story include finished floor surface.
BASEMENT. A storythat is not a storyabovegradeplane (see "Story above grade plane" in Section 202).
STORY ABOVE GRADE PLANE. Any story having its finished floor surface entirely above grade plane, or in which the
finished surface of the floor next above is:
1. More than 6 feet (1829 mm) above grade plane; or
2. More than 12 feet (3658 mm) above the finished ground
level at any point.
Still sounds like a crawlspace the OP describes.IMO With concrete floor we might have a basement.

IMO, the building code needs clarification. Of course I am not sure whether the nomenclature here matters- crawl/basement.

I had a situation where we added a master bedroom to a 2 story house with a full finished basement. Under the master bedroom was a 8' tall room with a slab that was only accessible from the one exterior wall that had access to grade. No windows only crawl space vents. Furnace was down there along with the water heater and all the duct for the bedroom conditioning.

Now is that room a basement- no access from inside the home and no communication to any part of the house? IMO, it is one large crawl space and by definition it can be either as I read the building codes.

BTW, nowhere in the code does it state a slab makes it a basement

 

[mwm1752]

The real intent of the wording was finished floor -- A room min -- 70 sqft & 7' ceiling

 

[mjf]

By me the utility company wants to see the ground rod somewhere within sight from the meter when they inspect the outside of the service.

Do you believe that is a written requirement of your utility?? or just what everyone is accustomed to doing?


Utility doesn't even inspect services around here. It's 3rd party electrical inspection agencies.

 

[mjf]

I'll try to be more specific to the location I am considering performing the work at.


100-150 year old house.

Stone foundation with wooden "floor" joist being supported by foundation.

7 feet beneath the underside of the previously mentioned wooden joist is dirt.

This "area" is only accessible by walking down a set of stairs from inside the dwelling.

The boiler in this "area" sits on cinder blocks.

someone poured a small concrete pad in this "area" at one time that the washer and dryer sit on.

Not sure if any of the above specifics matter in relation to my OP.

I'm just trying to figure out if it would be legal to install a "groundrod" within the footprint of the dwelling.

 

[mwm1752]

like Dennis said -- Sounds like a good place for the electrode

 

[mjf]

like Dennis said -- Sounds like a good place for the electrode

Thank you, everyone.

Of course, I'll also run it by the AHJ to get their take on it.

 

[Lectricbota]

Many basements are dirt and not really habitable. Of course one could pour a slab some day but there would be accessibility with a rod driven in the dirt.

That would then be a great chance for a UFER.

 

[Dennis Alwon]

That would then be a great chance for a UFER.

Without doubt on a new home but I assume we have an existing unit here.

 

[GoldDigger]

That would then be a great chance for a UFER.

Yes, if a slab is poured where there was earlier only dirt. But by itself that will not qualify as a UFER unless it is continuous with either new footings supplementing the dirt sidewall or new footings under vertical loads inside the space.

A friend of mine once excavated a shallow "basement" deeper by hand to make a real basement space, and had to bring in a contractor friend for emergency shoring when the outside foundation walls started to lose their support as the dirt fell into his new hole.

 

[Lectricbota]

Without doubt on a new home but I assume we have an existing unit here.

I realize that----just thinking if you pour a slab on top of you ground rod where some are bringing up the view that it would not be accessible, UFER I think, would alleviate those concerns.

 

[Lectricbota]

Yes, if a slab is poured where there was earlier only dirt. But by itself that will not qualify as a UFER unless it is continuous with either new footings supplementing the dirt sidewall or new footings under vertical loads inside the space.

A friend of mine once excavated a shallow "basement" deeper by hand to make a real basement space, and had to bring in a contractor friend for emergency shoring when the outside foundation walls started to lose their support as the dirt fell into his new hole.

OUCH:rant::jawdrop:

 

[kwired]

Do you believe that is a written requirement of your utility?? or just what everyone is accustomed to doing?


Utility doesn't even inspect services around here. It's 3rd party electrical inspection agencies.

Some utilities do inspect, but not for NEC issues, instead they may have their own service requirements, and if they are not met they can refuse to supply service.

Yes, if a slab is poured where there was earlier only dirt. But by itself that will not qualify as a UFER unless it is continuous with either new footings supplementing the dirt sidewall or new footings under vertical loads inside the space.

A friend of mine once excavated a shallow "basement" deeper by hand to make a real basement space, and had to bring in a contractor friend for emergency shoring when the outside foundation walls started to lose their support as the dirt fell into his new hole.

Some have to learn the hard way.

I realize that----just thinking if you pour a slab on top of you ground rod where some are bringing up the view that it would not be accessible, UFER I think, would alleviate those concerns.

Connection point to a ground rod and to a concrete encased electrode doesn't have to be accessible.

I wouldn't consider rebar in a slab to be a concrete encased electrode. Read 250.52(A)(3) carefully. A basement floor or other slab is not a "footing" or a "vertical foundations or structural components".

My opinion is if it is not near the exterior perimeter like a footing usually is, the dirt around it may eventually dry out and become less conductive. If you have high water table maybe this is not a problem - but you probably do not have a basement either as it will have water in it frequently.