In part of my house the copper pipe for the baseboard heaters run buried under the concrete floor slab. Does it work and is it permissible to install a grounding clamp to these pipes in order to provide grounding for electrical outlets?

I live in Denver, Colorado.

Thanks!

Absolutely 1000% NO.
This is NOT a legal, safe or valid source of an equipment ground.
The electrical panel is about your only choice.

Even a ground rod is not. The earth has nothing to do with the grounding terminal in a receptacle.

Thanks for your reply, but can you clarify why there are so many responses online that state that water pipes can be used for grounding? Also, why do you say that a grounding rod cannot be used? My electrical panel is grounded by a grounding rod.

Here's an excerpt from the NEC... I'm guessing I'm not understanding something.

NEC 250.5 Grounding and Bonding Grounding and Bonding "Electrodes include a metal underground water pipe in direct contact with earth for 10 feet or more, a metal frame of a building or structure, a concrete encased electrode or a ground ring"
And this one:
NEC 250-50 A premise's electrical service shall be connected to a grounding electrode system consisting of a metal underground water pipe in direct contact with earth for 10 feet or more, if available on the premises, and a supplemental electrode (a rod, pipe, or plate electrode.) An additional electrode shall supplement the buried water pipe electrode.

For what it's worth I have one grounding rod at my panel, another one in my crawlspace that has ground wires directly connected to receptacles. And also grounding clamps on cold water pipes in the crawlspace that connect to circuits in the house.

Thanks for your reply, but can you clarify why there are so many responses online that state that water pipes can be used for grounding?
Because those answers are given by folks who don't know what they are talking about. There are a LOT of armchair contractors and other pseudo-professionals out there.
I definitely correct those folks when I see them. It is sad that folks who are not professionals in a field think they are qualified to give advice.


There is a VERY big difference between the round hole in a receptacle (equipment ground) and a ground rod or the grounding electrode system in your house.
These two systems are both called grounding, but are two separate and exclusive systems. Ground rods and bonded water pipes have (almost) nothing to do with equipment grounding.

An equipment ground for a receptacle can be connected to a grounding electrode conductor or water pipe ONLY if said pipe is correctly being used as a grounding electrode and the connection is made within 5' of where the pipe enters the house.
This ensures that only the grounding electrode conductor is used for an equipment ground since this wire goes directly to the main panel and the connection should be solid and sound.
In this case you are NOT using the electrodes or the earth as the ground, you are using the grounding electrode conductor as a path to the main panel.

The safety equipment ground found in receptacles originates at the main panel and is created by the neutral to ground bond (main bonding jumper) found there.

This is a convoluted and confusing topic for even some professionals, so I understand the confusion to DIYer and lay people.

The panel needs at least one ground rod, so that is correct.

The "other" ground rod with wires grounding receptacles, and the grounding wires attached to heating pipes, are both incorrect.

You don't understand something because the Code is not to be read piece by piece. You quoted the NEC sections relating to the grounding electrode specifically. That would be the ground rod you have connecting to the panel.

That is the only point system grounding to earth is allowed.

All equipment grounding, the bare or green conductor from the receptacles, and all other equipment grounding from all circuits must be connected to that grounding point at the panel.

Stan is so correct that grounding is so a complicated issue, many people interpret the topic so wrong and simplistic.

We can discuss this further if you have any additional specific questions.

Thanks to both of you for your help. I guess the next question would be... If I need to replace ungrounded receptacles with grounded ones, can continue to use the hot and neutral wires already in place and run a new green wire of the same gauge back to my panel? Or is it OK to run the green wire to the closest grounded circuit? The wiring appears to be 12 or 14 ga copper installed in the late 50s.

As an aside, how do electricians physically tackle this job? Ive looked at the long flexible drill bits but they're a bit pricy for a DIY-er.

Replacing 2 wire receptacles with 3 wire devices can only be done if you protect the circuit or receptacles with GFI devices.

Using a breaker you can do the entire circuit, or individual GFI receptacles can be used, and protect and devices downstream. Any 3 wire receptacles with no ground but GFI protected must be labeled "No Equipment Ground".

You can add a ground wire, but it cannot just connect to the closest ground. It must be brought back to any one of the points as outlined by Section 250.130 (C) of the NEC.

From the NEC 2008 Edition Section 250.130:

(C) Nongrounding Receptacle Replacement or Branch
Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates
(4) For grounded systems, the grounded service conductor within the service equipment enclosure
(5) For ungrounded systems, the grounding terminal bar within the service equipment enclosure.

My opinion is if you can run a ground wire to one of these limited points, you can install new wiring with the equipment ground included.

You can add a ground wire, but it cannot just connect to the closest ground. It must be brought back to any one of the points as outlined by Section 250.130 (C) of the NEC.

From the NEC 2008 Edition Section 250.130:

(C) Nongrounding Receptacle Replacement or Branch
Circuit Extensions. The equipment grounding conductor of a grounding-type receptacle or a branch-circuit extension shall be permitted to be connected to any of the following:
(1) Any accessible point on the grounding electrode system as described in 250.50
(2) Any accessible point on the grounding electrode conductor
(3) The equipment grounding terminal bar within the enclosure where the branch circuit for the receptacle or branch circuit originates
(4) For grounded systems, the grounded service conductor within the service equipment enclosure
(5) For ungrounded systems, the grounding terminal bar within the service equipment enclosure.

My opinion is if you can run a ground wire to one of these limited points, you can install new wiring with the equipment ground included.I fully agree. Especially with the last sentence. ;)