House Grounding - Upgrade by adding UFER?

[larry4406]

My house was built in 1987.

There is a solid copper ground wire leaving the panel (#4?) to the outside but from there I have no clue regarding the assumed two (2) ground rods spaced at minimum 6' apart with continuous wire which should have been required at the time house was built. There is ZERO opportunity to inspect what is here as the prior owner built a stone patio with stone wall tight to the house. Also no ability to add anything close to the panel due to the stone patio and stone wall tight to the house. Lastly, I don't have access to testing equipment to test the existing grounding system adequacy.

The house has copper water piping and the electrician ran stranded copper ground wire from the attached garage electric panel into the basement and bonded it to the copper water piping.

We are putting on a kitchen extension. I am thinking of installing a UFER ground in the footing of this extension and connecting it to the same stranded copper wire that runs to the basement copper plumbing.

Thoughts?

 

[Jinks]

Look at wikipedia's description of UFER ground. You probably don't need it in Virginia, but it won't do any harm. Back in the 70's we were loosing a lot of telephone switch boards to lighting strikes. A guy at Bell Labs found the cause to be difference in ground potential (one ground source was better than another). The solution was to bond all three grounds (ground rod, power ground, & water pipe) together giving a building an even ground potential. We spent two years bonding grounds in every building in north Florida & quit loosing switch boards to lightening. You could probably just drive a good ground rod, bond it with the power ground & water pipes, & have great grounding potential.

 

[Chuckster in NJ]

Throw some 1/2” rebar (longer than 20’) into the footing while it is "available" prior to the pour and run a #4 to it as a Ufer ground. You can never "overdo" a grounding system....... Grounding and bonding is the most important part of a electrical system.
In NJ a Ufer ground on an addition is not a code requirement unless the service is being moved into the addition or the service is being upgraded.
A Ufer is a good thing to do and you won’t be sorry you did it.

 

[BillK]

I think the biggest issue with doing the Ufer is that you also need to bond it to the other ground coming out of the panel. If not you could run into the problem that Jinks described. I just finished reading a book on grounding for Amateur Radio installations and that was one thing that they stressed quite a bit. All of the grounds need to be hooked together. Depending on where your new kitchen is compared to your panel it might be more trouble than its worth.

 

[larry4406]

I will definitely install the UFER ground in the footing as only one chance and turn it up for access. Easy to bond it to the house ground that runs between the attached garage service panel and copper piping in the basement as the ground wire runs right past the addition area.

All new construction here in northern VA and MD where I build homes the counties require UFERs (it was not imposed as part of my renovation permit however).

The odd thing about UFERS is that everyone says 20' of continuous rebar. That is the max length of rebar (at least in this area). So if you turn it up to be accessible, then there is less than 20' encased in the footer. I get blank stares from inspectors

One inspector said to me that the rebar needs to overlap minimum of 5 diameters and be wire tied to be considered continuous to address this conundrum. Call me a skeptic but I don't think wire tying effectively bonds the bars together adequately. Another inspector told me to weld the rebar; yeah right.

In Montgomery County MD where I built for 7+ years recently, we ran continuous #4 copper in the footing tied to the rebar cage for a minimum length of 20' encased in the footing then turned the wire up to the panel. No arguing on that. This is what I did on my detached barn project couple years ago and plan on doing here.

 

[Chuckster in NJ]

The odd thing about UFERS is that everyone says 20' of continuous rebar. That is the max length of rebar (at least in this area). So if you turn it up to be accessible, then there is less than 20' encased in the footer. I get blank stares from inspectors


.

A Ufer connection to the rebar should not be bent up to be accessible........ Use an approved clamp and encase the entire connection in concrete.
You can accomplish the 20’ long rebar required length by tying multiple lengths of rebar together with tie wires.

BTW! You can also use a 20’ long #4 BARE copper wire encased in concrete as a Ufer in place of rebar.

 

[larry4406]

A Ufer connection to the rebar should not be bent up to be accessible........ Use an approved clamp and encase the entire connection in concrete.

You can accomplish the 20’ long rebar required length by tying multiple lengths of rebar together with tie wires.

BTW! You can also use a 20’ long #4 BARE copper wire encased in concrete as a Ufer in place of rebar.

The inspectors here require the clamp to be accessible unless it is a non-reversible crimp. Thus encasing the clamp connection in concrete would be a no-no.

As I stated, the rebar is wire tied together at the lapped splice. I am just uncertain that simply tying it to together is a good as a continuous piece and lasting.

Yes on the continuous #4 copper copper wire as I stated. This is what I plan on doing. There will be 20' in the concrete encased footing and it will continue and connect to the aforementioned house ground.

 

[John in OH]

The inspectors here require the clamp to be accessible unless it is a non-reversible crimp. Thus encasing the clamp connection in concrete would be a no-no.

As I stated, the rebar is wire tied together at the lapped splice. I am just uncertain that simply tying it to together is a good as a continuous piece and lasting.

Yes on the continuous #4 copper copper wire as I stated. This is what I plan on doing. There will be 20' in the concrete encased footing and it will continue and connect to the aforementioned house ground.

Yeah, I never understood how a simple tie-wire connection makes an adequate extension of the rebar ground. The code goes to all the effort of specifying rebars size, ground wire size, clamp style ... and then the code poops the bed and seems to find a randomly made, quasi-tight connection (with undefined contact )made between rusty rebar with some crappy thin steel tie-wire as adequate!!!

Kinda like lipstick on a pig!!

 

[strutaeng]

Yeah, I'd talk to your electrical inspector. I did a 22x65 addition to my house and left the uffer connected to one of the #5 top rebars of the grade beam. Whatever the code said. I think I did like 22' of that #4 solid copper?

Anyway, my mistake is that I hooked it up the subpanel to the addition. The city electrical inspector told me to remove it. I later talked to my nephew who is an apprentice electrician and he told me the uffer can only be connected to the main panel.


Regarding the tying of the bars, my guess is that electricity would transfer across as long as the bars are side-by-side. After all, in a lightning strike you are talking a lot of voltage. Kinda how a force is transferred when you lap rebars. Once encased in concrete, you are not relying on the tie wire to tranfer the load, but rely on the bond stresses. I dunno. My background is in structural. I'm not a sparkie.