Thread: Grounding Requirements

Is a Ufer alone sufficient to satisfy residential service grounding requirements?

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Originally Posted by A.D. Miller

Is a Ufer alone sufficient to satisfy residential service grounding requirements?

I don't think so. Of course that is just me.

I think and always have that there should be 2 points of grounding the system.

If one goes under the slab then there should be a ground rod. Most of the installs I see nowadays has this. There are still many that believe that the Ufer, as you say, is believed by them to be sufficient.

A proper UFER install does not need to be supplemented according to the NEC.

Originally Posted by A.D. Miller

Is a Ufer alone sufficient to satisfy residential service grounding requirements?

Possibly. Or, "it depends".

If no other grounding electrodes exist, then Jim is correct: the NEC does not require a concrete encased electrode to have an auxiliary grounding electrode.

If other grounding electrodes "are present" then all grounding electrodes are required to be connected together.

Also consider this: If you are connecting to a slab on grade concrete encased electrode, is that slab really in "in direct contact with the earth". In most cases, the moisture barrier does not go under and up the sides of the footing, leaving the sides of the footing in "direct contact with the earth" ... as long as the footing is properly down in the earth by the required 12" minimum.

If you want the right answers, you need to ask the right questions.

A Ufer ground does not require any additional grounding electrode, not even in places that require two ground rods. Simply put, the performance if the Ufer is so vastly superior to other methods as to make them irrellevant.

BUT ....

All the stuff that formerly needed to be bonded still needs to be bonded. For example, the water pipes. To be fair, this bond is often to be found at the water heater, rather than where the water pipe enters the house. It is also likely that you are required to bond the gas line.

Now, whether that cold water pipe is a 'Grounding electrode" or simply bonded as an "equipment grounding conductor" is a distinction best saved for IEEE meetings; you have no way to tell which way the electricity will flow.

I'll say that Jerry, Jim and John are all correct. Jim's post is quick and to the point.

Originally Posted by John Steinke

Now, whether that cold water pipe is a 'Grounding electrode" or simply bonded as an "equipment grounding conductor" is a distinction best saved for IEEE meetings; you have no way to tell which way the electricity will flow.

John, no need for a meeting on this.
A metallic water pipe in contact with the earth for 10' or more MUST be used as a grounding electrode. It must also be supplemented by another electrode. A Ufer certainly qualifies as a supplemental electrode.
A metallic water pipe system is not, and should NEVER be, an "equipment grounding conductor", but it must be bonded.

Suffice to say, if a Ufer exists, you never have to add another electrode.

Originally Posted by Speedy Petey

Suffice to say, if a Ufer exists, you never have to add another electrode.

There are the key words ... "add" ... "another electrode".

Speedy, it's a point of vocabulary. The wire between the panel and that cold water pipe is, in code language, either a "grounding electrode conductor" or a n "equipment grounding conductor." Those are the code terms, and which is correct depends entirely on whether the pipe is the primary 'grounding electrode' of the structure. Or, in simpler terms, which way the electricity is flowing - something you have no way to measure.

If you have a Ufer, that is your grounding electrode. Sure, you can add supplimentary grounding electrodes, and the code still requires the water pipe to be bonded .... but IMO the days of considering the water pipe as a 'grounding electrode' are long gone - especially when another grounding electrode is present.

Why do I say that? Because we have no idea what exists after the pipe enters the ground. We simply cannot depend on that water pipe to provide any lightning or surge protection; for all we know, some plumber switched to plastic pipe as soon as the pipe exited the wall on the other side.

Yet, we still have the risk that 'ordinary' electricity will be distributed through the house when some plumbing appliance shorts out. Hence, the need to bond the piping - usually at those appliances.

Originally Posted by John Steinke

Speedy, it's a point of vocabulary. The wire between the panel and that cold water pipe is, in code language, either a "grounding electrode conductor" or a n "equipment grounding conductor." Those are the code terms, and which is correct depends entirely on whether the pipe is the primary 'grounding electrode' of the structure. Or, in simpler terms, which way the electricity is flowing - something you have no way to measure.

Actually those are not the code terms. The two things it could be are "Grounding electrode conductor" and "Bonding jumper".

A wire to a water pipe from a service panel would NEVER be an "Equipment grounding conductor".

250.104(A) is quite clear on this.
The water pipe bond wire is sized by T250.66 which is the same chart for sizing grounding electrode conductors.


250.104 Bonding of Piping Systems and Exposed Structural Steel.

(A) Metal Water Piping. The metal water piping system shall be bonded as required in (A)(1), (A)(2), or (A)(3) of this section. The bonding jumper(s) shall be installed in accordance with 250.64(A), (B), and (E). The points of attachment of the bonding jumper(s) shall be accessible.

(1) General. Metal water piping system(s) installed in or attached to a building or structure shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with Table 250.66 except as permitted in 250.104(A)(2) and (A)(3).

If a house is plumbed with plastic pipes. Then is there a need for a bonding jumper, or dose house only need a UFER or a ground electrode conductor?

Since plastic pipe is non-conductive there is no need for the bonding.

Originally Posted by Jack Wingo

If a house is plumbed with plastic pipes. Then is there a need for a bonding jumper, or dose house only need a UFER or a ground electrode conductor?

Jack,

As Jim said, the plastic water piping does not need to be bonded to ground.

The last part is that, yes, if present (and there almost always is one present) a concrete encased electrode needs to be connected to the service, the conductor connecting the concrete encased electrode is the grounding electrode conductor.

Meaning it is not either/or, it is both - the grounding electrode conductor connects the service to the concrete encased electrode.