grounding rod question
- Thread starter 06manvan
- Start date
sberry
Banned
The primary grounding electrode is now the footer steel and there needs to be a place to connect it. My footer steel is bonded to the building, a whole array of it sits basically in water with water behind it a bit in a loading dock and for some reason when I built I pounded a rod thru it, acorn under the footer, 8 ft of standing water. The whole place is a giant uffer plus the 2 aux rods and in some sense 300 ft of steel pipe casing.
sberry
Banned
I remember a couple lights coming on when I had a problem with a well. I asked the well guy about proper grounding for the service and he didn't know squat. I quiz a couple eld timers on a forum I know they know and the guy says bug it to the steel casing and I say welding a lug to it work, you bet. For that only 1 electrode and no rods needed or wanted.
matt_i
Well-known member
Leave one bar approx. 1-2 feet proud of the footing/stem wall top for use later. In my opinion it needs to be encased in a concrete wall or pad footing or thickened edge/grade beam that bears directly on the soil for it to work, and not a rebar grid in a simple flat slab that's supported by a vapor barrier and then a crushed gravel pad. The action of the concrete against the soil multiplied by all of the surface area is what enables it to work. Google Ufer Ground for more info and code references.
ddawg16
Well-known member
Do some research on Ufer grounds.
Most jurisdictions are going to want at least a 20' long piece of #4 or #6 copper wire embedded in your foundation. In most cases, the rebar alone is not enough. And, the copper wire needs to be at the bottom of the footing.
But nothing wrong with also tying the copper wire to your rebar.
Me? I have the copper wire....tied to my rebar....tied to my existing ground rods and copper plumbing.
You can never have enough grounding....
Most jurisdictions are going to want at least a 20' long piece of #4 or #6 copper wire embedded in your foundation. In most cases, the rebar alone is not enough. And, the copper wire needs to be at the bottom of the footing.
But nothing wrong with also tying the copper wire to your rebar.
Me? I have the copper wire....tied to my rebar....tied to my existing ground rods and copper plumbing.
You can never have enough grounding....
alfredeneuman
Well-known member
You may want to take your own advice??
Ufer grounds are known in the NEC as "concrete encased electrodes"
From the 2011 NEC
(3) Concrete-Encased Electrode. A concrete-encased electrode shall consist of at least 6.0 m (20 ft) of either (1) or (2):
(1) One or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (1⁄2 in.) in diameter, installed in one continuous 6.0 m (20 ft) length, or if in multiple
pieces connected together by the usual steel tie wires, exothermic welding, welding, or other effective means to create a 6.0 m (20 ft) or greater length; or
(2) Bare copper conductor not smaller than 4 AWG
An inspector must accept these, unless there is a local amendment.
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alfredeneuman
Well-known member
06manvan
A rebar in the dirt is insufficient.
You need genuine ground rods - 2 of them (unless you can prove that 1 provides less than 25 ohms to ground)
They need to be buried to a depth of 8', and be more than 6' apart.
They need to be connected to the ground bar in the panel with a #6.
A rebar in the dirt is insufficient.
You need genuine ground rods - 2 of them (unless you can prove that 1 provides less than 25 ohms to ground)
They need to be buried to a depth of 8', and be more than 6' apart.
They need to be connected to the ground bar in the panel with a #6.
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BADSIX
Well-known member
this ^^^ I just had mine inspected and this is what they wanted to pass code
Jay D.
Jay D.
Falcon67
Well-known member
I used the 20' of #4 in my slab, no problem with inspection. BUT - only because I'm here and not 20 miles down the road, where they require both a UFER and the copper line or driven rods. The why could be debated, only talking to local contractors, architects, home builders, etc - you get a universal answer to the "permits and inspections" question of "Don't get me started.' 
wyliesdiesels
Well-known member
A stick of rebar pounded into the dirt would NOT qualify as a grounding electrode. Buy 2 8' rods, acorn clamps and some bare solid #6 cu wire and be done with it.
How is the garage being fed? From a house or its own service?
How is the garage being fed? From a house or its own service?
MushCreek
Well-known member
I just installed two 8' ground rods, which is what they usually require here. The inspector told me I only needed one because it is a sub-panel from the house. Huh? Either way, the second ground rod can't hurt, and after pounding on it for an hour, I'm going to use it!