concrete encased electrode connection

[ga77]

Is the #4 CU connection to the concrete encased electrode required to be made IN the concrete? If a portion of the rebar is left sticking out of the concrete are you allowed to connect there (technically, this portion is not a concrete encased electrode but a buried or exposed rebar)?

 

[charlie]

Re: concrete encased electrode connection

It depends on the AHJ and any amendments to the building codes in your area. It is my understanding that all rebar must be encased in concrete. If that rule is not changed, the connection must be made in the footer.

 

[tom baker]

Re: concrete encased electrode connection

Some areas allow the connection to be made to the rebar above the footing. Oregon has a detail in its speciality code that specifically shows this.
If the connection is encased, its a $20 clamp, vs a $2.50 acorn clamp for exposed

 

[don_resqcapt19]

Re: concrete encased electrode connection

Tom,

If the connection is encased, its a $20 clamp, vs a $2.50 acorn clamp for exposed

Why? All clamps suitable for direct burial are also suitable for concrete encasement per UL.
Don

 

[hurk27]

Re: concrete encased electrode connection

When I was doing work in Florida they use to have a section of re-bar stubbed out right under where the service would go, they would paint it green which I would have to wire brush off. :roll:

 

[tom baker]

Re: concrete encased electrode connection

I was wrong on the acorn clamp it listed for concrete encasement. The $20 clamp would be a burndy GAR type, which is listed for concrete encasement. but the acorn clamp has to go over an end and the gar can go over the run, however while the acorn clamp can be used, some may not be listed for rebar.

 

[George Stolz]

Re: concrete encased electrode connection

By supposition, the exception to 250.50 all but states it doesn't have to be encased: "without disturbing the concrete." If there you don't have to disturb the concrete, then you're required to use it.

The only way to use it without disturbing the concrete, is for the connection to be outside.

 

[ga77]

Re: concrete encased electrode connection

Originally posted by georgestolz:
By supposition, the exception to 250.50 all but states it doesn't have to be encased: "without disturbing the concrete." If there you don't have to disturb the concrete, then you're required to use it.

The only way to use it without disturbing the concrete, is for the connection to be outside.

Or for the connection to be made before the concrete is poured. I don't have my code book in front of me but I believe the exception regarding disturbing the concrete is for existing installations where it was not intended to have the concrete chipped away to get at the rebar.
Let's limit the scope of my question to new buildings only.

[ March 24, 2005, 07:35 AM: Message edited by: ga77 ]

 

[George Stolz]

Re: concrete encased electrode connection

Well okay, but: If it's okay for existing installations to connect outside the concrete, and there is no rule prohibiting it in new ones, then it's permitted.

Carry on...

 

[powermac36]

Re: concrete encased electrode connection

Article 250.52, specifies: "the concrete encased electrode conductor shall be 20 ft conductor not smaller than # 4 AWG ," yet;
Article 250.66(A) states: "that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger thatn 4 AWG wire ."

I've heard arguments that 250.66(A) gives the ok to leave a portion of the re-bar out of the conrete, and the bonding jumper can be #8-6CU to, say, a residential service less than 200 ampere rating.

 

[buck33k]

Re: concrete encased electrode connection

If the connection to the rebar is not encased, it must be accessible. 250.68(A) I have seen this accomplished using a plastic mud ring and plate where the rebar is stubbed up.
Buck

 

[pierre]

Re: concrete encased electrode connection

I have heard the same requirements as Charlie. My advice is to contact the building inspector to find out the rebar requirement in your jurisdiction, than you know where you need to start from.

I am consulting(not inspecting) on a project now, where the building has been blasted into bedrock (imagine the inspector asking for groundrods

 

[charlie]

Re: concrete encased electrode connection

Pierre, that will make a great installation. Well past the Code requirements and it will serve the owner well.

 

[eprice]

Re: concrete encased electrode connection

One of the reasons for a minimum amount of concrete cover for rebar is to protect the rebar from moisture so that it will not be weakened by corrosion. Rebar should not be stubbed out underground or where exposed to weather. We have allowed the rebar to be stubbed up inside the building or inside a framed stud space. As Buck mentioned, in these cases the connection must be kept accessible.

 

[benaround]

Re: concrete encased electrode connection

My book says "An electrode--encased by at least 2in of concrete,LOcated within and near the bottom of a concrete foundation or footing that is in direct contact with the earth"--- It does not say " or bent up into an above grade area" . I guess it's an option in some areas.
Arizona has been using UFERS for quite awhile now,most EC opt for tying 20ft. #4 to grid with no connection needed underground.

frank

 

[eprice]

Re: concrete encased electrode connection

Frank,

But 250.52(A)(1)says 20 ft of one or more bars and that these bars my be bonded together by the usual steel tie wires. The bar that is bent up will have it's horizontal leg tied to other bars in the footing so that the 20 ft of bar at the bottom of the footing will be accomplished.

After adoption of the 2005 NEC, the #4 copper in the footing not connected to the reinforcement will not satisfy the code. The rebar is there and will need to be used as an electrode. Connecting the #4 copper to the rebar with a proper clamp will satisfy this requirement.

 

[ga77]

Re: concrete encased electrode connection

Originally posted by georgestolz:
Well okay, but: If it's okay for existing installations to connect outside the concrete, and there is no rule prohibiting it in new ones, then it's permitted.

Carry on...

I gave your reply some thought. I think that what is allowed for existing installations may not be allowed for new. In other words, a less than perfect connection on existing installations is better than no connection at all. But for new installations the best connection is in the concrete where the connection is not subject to any kind of deterioration. I don't buy the argument that an exception for existing installations applies to the general rule. An exception is just that and is narrowly defined by the language in the exception.

 

[George Stolz]

Re: concrete encased electrode connection

Originally posted by ga77:
In other words, a less than perfect connection on existing installations is better than no connection at all.

I'll buy that reasoning.

I don't buy the argument that an exception for existing installations applies to the general rule. An exception is just that and is narrowly defined by the language in the exception.

True, but when you step away from what the code forbids or requires, to what you think the code intends, devining meaning from exceptions and portents sometimes yields results.

There's no code requiring/forbidding it aboveground/embedded, so you end up where you started: calling the inspector.

Originally posted by powermac36:
Article 250.52, specifies: "the concrete encased electrode conductor shall be 20 ft conductor not smaller than # 4 AWG ," yet;
Article 250.66(A) states: "that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger thatn 4 AWG wire ."

I've heard arguments that 250.66(A) gives the ok to leave a portion of the re-bar out of the conrete, and the bonding jumper can be #8-6CU to, say, a residential service less than 200 ampere rating.

I have been going rounds with this trying to make sense of it. One section is defining an electrode, and the other is specifying the size wire to pull to it, how does "250.66(B) gives the ok to leave a portion of the re-bar out of the concrete" pop out?

[ March 29, 2005, 10:31 PM: Message edited by: georgestolz ]

 

[infinity]

Re: concrete encased electrode connection

What about this scenario, if the footer is not poured yet but contains 3/8" rebar then is a concrete encased electrode still required? I just started a service upgrade at a dwelling with an addition that will have new footers with 3/8" rebar that was specified by the architect. Since the footer is only formed could it be argued that I would still need to install 20' of bare #4 AWG copper in the footer or is nothing needed since the rebar is less than 1/2" as specified in 250.52(3)?

 

[don_resqcapt19]

Re: concrete encased electrode connection

A concrete encased electrode is only required to be used if it is "present". There is no concrete encased electrode in your installation and the code does not require you to install one.
Don