Electrician says corroded ground electrode needs replacing

[redikillowatt]

John120/240 - are we talking about GEC's - not bonding conductors / jumpers? Maybe allowed methods (you mentioned) are allowed on either. I was referring ONLY to rule on "splicing" bonding jumpers, for the moment.

The NEC is written in such plain, easy to follow manner but I thought the main GEC from panel ALWAYS had to be continuous, unbroken. Maybe the 2 methods mentioned, of permanently connecting (splicing) 2 wire sections are the only exceptions.

Reading NEC is like reading IRS tax code. One rule refers to another & another & ...

 

[kwired]

Hmmm, they seem to hold up even in chemical plants past 50 years. On the other hand I have seen severely corroded reinforcement steel in wet concrete.

That depends on the chemicals and whether or not they come in contact with the grounding electrode.

They don't last even 5 years at bulk fertilizer storage and distributiuon plants in a lot of cases. But neither does any other electrical equipment. You can use correct enclosures, the corrosive environment still finds a way inside and destroys everything inside. Keeping as much as possible in a mechanical room like motor controllers, overcurrent devices, etc. is the best you can do.

 

[George Stolz]

As in, if bonding 2 electrodes 100 ft apart, NOT being allowed to use (2) 50 ft pieces of wire - clamped, spliced, twisted together, in between those 2 electrodes. Is that correct?

No. That is why I said you're mistaken. I can use a 100 chunks of wire connected together with wagos to connect electrodes if I choose.

I can't find the full text of NEC 250.53(C)...

I don't understand your continued interest in this topic (or this forum) if you're a GC without a copy of the NEC - but it's a free country, knock yourself out.

 

[redikillowatt]

Thanks for clarification & everyone's replies.

Why as a GC, am I interested? Because much of the work is done outside of city limits, w/ no inspectors. Plumbers & electricians take short cuts or make mistakes. There's no one but me or foremen to catch the big errors & it's my reputation that would be hurt - not the subs.

Today on another new home job, I looked at the clamp used on the 3/8 Ufer rebar. It was too large for # 3 rebar, so the electrician just stuck a steel machine screw between rebar & pipe clamp to take up slack. The rebar was also pushed over too far & nailed, so the Ufer clamp wouldn't be "easily accessible" thru the wall box, after rocking. :happysad: Plumbers didn't put blocks behind shower valves, & secure valves. This is PEX. All kinds of crap like that.

These are nice, expensive homes & not the cheapest subs I can find. It's just many try to cut corners when no inspectors are coming.

Thanks again.

 

[George Stolz]

The clamp wasn't too small, the rebar was. I hope that wasn't the only "electrode". On the bright side, at least you can bury it behind the drywall then!

 

[redikillowatt]

I get your drift, but that was some "engineering." There are rebar listed clamps that will fit 3/8, but I guess code requires at least 20 ft encased to be 1/2 in? Yes, there is an 8 ft driven rod just outside the slab. Each electrode has a separate GEC from main panel, which I believe is allowable. Electrodes aren't bonded because each has a separate GEC.

Mind you, I didn't design the slab or specs for the Ufer. Couldn't they have put just 20 - 30 ft of 1/2 in. rebar in slab to satisfy NEC ufer code, & tied it to rest of 3/8 rebar in footing?

No, the 3/8 bar won't be hidden forever - unless leave out the access box so an electrician can get to it in future. I believe code says Ufer connection should be accessible.

 

[George Stolz]

It's not a Ufer, so there are no codes requiring random stuff connected to the service for sport to be accessible.

If there was a section 20' long of 1/2" in that foundation, and it complied with all the different stipations, then a connection to that portion would be required. I don't believe connecting to 3/8" that is connected to 1/2" downstream would be compliant.

 

[redikillowatt]

No, I meant since 3/8 is in the footing, couldn't a 20+ ft piece of 1/2 rebar been put in, tied to the 3/8 in rest of footing (regardless of what you call it). Actually take a bit more than 20 ft to allow stub up. But, isn't 20 ft of 1/2 in. CEE (rebar) all that's required?

 

[kwired]

If you put 20' of 1/2 rebar in the footing then it qualifies as a CEE.

NEC does not require the use of a CEE, it requires to use a CEE if it present.

3/8 rebar does not qualify as a CEE, but you don't have to put in 1/2 inch just to make a CEE. But you can if you want. You can also just put 20 feet of 4 AWG copper in the footing if you wish to make a CEE.

 

[Fulthrotl]

On a remodeling addon job, the electrical contractor says the single grounding electrode needs replacing because it has rust at the top where a brass acorn clamp is attached (rod is exposed above grade). It is rusted, but clamp looks good. He also wants to replace the short GEC from panel to driven rod.

Is it necessary to replace a ground electrode because it has rust? For grins, I cleaned a spot on the rod below the brass grounding clamp & shined a spot on outside of brass clamp a bit & also a spot on GEC ( above the ground clamp). Resistivity between clamp & rod, and the GEC (from above clamp) to rod - below clamp - then were each < 1 ohm. Seems to indicate conductivity between both GEC, brass clamp & rod are still good, in spite of corrosion.

Can't say about resistance between such rusty ground rods & earth in a high rainfall area like this. He didn't check that.
The rod & clamp above ground were dry at the time of testing, but it has rained w/in last week.

I've worked on hundreds of older homes w/ similar looking rods & electricians never give them a 2nd look. I wonder if inspectors would require replacing rusty, but otherwise solid driven ground rods or what the actual requirements are for deciding if a driven ground rod needs replacing?

depends on the soil. we have a local requirement for stainless steel ground rods and cadweld.
huntington beach is an oil town, and the soil is pretty agressive.

ground rod has surface corrosion but is sound? wire brush it and shoot a $7 one shot cadweld
to attach the conductor to the rod... fifteen minutes of professional time...

 

[CopperTone]

On a remodeling addon job, the electrical contractor says the single grounding electrode needs replacing because it has rust at the top where a brass acorn clamp is attached (rod is exposed above grade). It is rusted, but clamp looks good. He also wants to replace the short GEC from panel to driven rod.

Is it necessary to replace a ground electrode because it has rust? For grins, I cleaned a spot on the rod below the brass grounding clamp & shined a spot on outside of brass clamp a bit & also a spot on GEC ( above the ground clamp). Resistivity between clamp & rod, and the GEC (from above clamp) to rod - below clamp - then were each < 1 ohm. Seems to indicate conductivity between both GEC, brass clamp & rod are still good, in spite of corrosion.

Can't say about resistance between such rusty ground rods & earth in a high rainfall area like this. He didn't check that.
The rod & clamp above ground were dry at the time of testing, but it has rained w/in last week.

I've worked on hundreds of older homes w/ similar looking rods & electricians never give them a 2nd look. I wonder if inspectors would require replacing rusty, but otherwise solid driven ground rods or what the actual requirements are for deciding if a driven ground rod needs replacing?

Sounds like the electrician is just doing a thorough job. Why not replace anything rusted while you are remodeling if it is questionable. It sounds like it won't cost that much to do anyway.
it would be like opening up a wall and you find a stud in the wall partially rotted - maybe it will be fine but while you are there, why not shore it up with another stud or replace it?

sometimes it is better to not be penny wise and pound foolish.

 

[weressl]

That depends on the chemicals and whether or not they come in contact with the grounding electrode.

Of course but grounding rods ARE also available in different materials and the appropriate can and should be selected for the application.

They don't last even 5 years at bulk fertilizer storage and distributiuon plants in a lot of cases. But neither does any other electrical equipment. You can use correct enclosures, the corrosive environment still finds a way inside and destroys everything inside. Keeping as much as possible in a mechanical room like motor controllers, overcurrent devices, etc. is the best you can do.

Exactly and that is why SS or polycarbonate enclosures without environmental air purge applied to them are pretty useless. Centralized location of controllers in MCC/Switchgear rooms were established for the very same reason.

 

[cowboyjwc]

Well since an acorn clamp is approved for burial, I don't think a little rust is going to hurt it any.

 

[renosteinke]

It's been my observation that the worst corrosion always takes place within the first few inches of the rod entering the soil.

This makes sense; you need oxygen to make rust, and once the dirt gets packed down the corrosion is blocked.

Any doubt, just dig down a single shovel bite and look at it.

 

[kwired]

It's been my observation that the worst corrosion always takes place within the first few inches of the rod entering the soil.

This makes sense; you need oxygen to make rust, and once the dirt gets packed down the corrosion is blocked.

Any doubt, just dig down a single shovel bite and look at it.

And unless the rod is longer than 8 feet it needs to be completely buried and then this will not be much of a problem.

 

[George Stolz]

And unless the rod is longer than 8 feet it needs to be completely buried and then this will not be much of a problem.

Do you actually install your ground rods below permanent moisture level?

 

[John120/240]

Do you actually install your ground rods below permanent moisture level?

Drive the ground rod to a depth of 7'10" install acorn w/GEC & move on.

 

[kwired]

Do you actually install your ground rods below permanent moisture level?

There are areas around here with pretty high water table - so yes sometimes I do without even thinking about it.

 

[George Stolz]

There are areas around here with pretty high water table - so yes sometimes I do without even thinking about it.

What does the inspector say when he looks for a ground rod and finds nothing?

 

[kwired]

What does the inspector say when he looks for a ground rod and finds nothing?

He finds nothing because there is a CEE and a ground rod was not required:happyyes:

If there is a ground rod he did not find it because he did not bring a shovel, or he did not dig deep enough.