Aluminum Ground - Allowed??

Is single strand aluminum allowed to be used as a ground? I’d never seen this before?

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**250.62 Grounding Electrode Conductor Material.
**The grounding electrode conductor shall be of copper, aluminum,
or copper-clad aluminum. The material selected shall be resistant
to any corrosive condition existing at the installation or
shall be suitably protected against corrosion. The conductor
shall be solid or stranded, insulated, covered, or bare.
**250.64 Grounding Electrode Conductor Installation.
**Grounding electrode conductors shall be installed as speci-
.ed in 250.64(A) through (F).

**(A) **Aluminum **or Copper-Clad Aluminum Conductors.
**Bare aluminum or copper-clad aluminum grounding conductors
shall not be used where in direct contact with masonry
or the earth or where subject to corrosive conditions.
Where used outside, aluminum or copper-clad aluminum
grounding conductors shall not be terminated within 450 mm
(18 in.) of the earth.

Paul - thanks for the fast response. Dumb question though…250.64 states that bare aluminum shouldn’t be used if it’s in direct contact with masonary or earth, is this ground still ok? It was mounted along a joist and grounded only to the plumbing. Nothing touching masonary or earth?

Paul - also, I took your electrical class several months ago. Great class.

As long as it is not in contact it’s okay. This appears to be a bonding conductor rather than a grounding conductor.

Were you able to see where the piping was in contact with “earth?”

Gotta love the grounds and neutrals that are twisted together!

Yeah saw that too, especially how they are barely under the screws, or even multiple wires under a screw. Defer to a qualified electrician. But then this is beyond the scope of the OP. :wink:




Ok…now the question Jeff bought up is…is this the Bonding or is this the GEC…quite funny now…

While 250.102 does have a " sniglet" about the equipment bonding conductors being copper or some other corrosive resistant material…

Generally Alum is acceptacle…BUT used very rare…

Oh…with that said and hearing as I go around the country doing these seminars…the understanding of BONDING is not very well known…except for in Sacramento, CA…where when I was explaining it they all had a EUREKA moment…lol…

IN this case based on what I see…I would not say it is the bonding conductor…since in older homes it is probably rare they even knew how do bond correctly…so I would say it is the GEC to the Water Pipe…but again I could be wrong…lol…but I doubt it…:slight_smile:

Oh…who can I guess this…look at the picture of the panel…it looks like the small terminal buss under the large one has the larger solid aluminim running out of it…BUT no other larger copper lines…??? SO…the knew about the GEC before they truly undstand the meaning of bonding…so I can safely say I think it was the attempt at the GEC…


This had to have been the grounding wire. I did not see any other grounds. No copper or other wires coming out of the box. I didn’t see a bonding element either. I am recommending further evaluation because of double taps, and signs of arching.

Thanks everyone for their help.

I doubt you’re wrong, but the question remains in my mind (based on what’s visible in the picture). Is that water pipe “effectively grounded?”

Also, if I remember correctly, in residential applications the GEC attachment should be within 5 feet of the point where the water pipe enters the home.

The picture in the OP shows the piping system in, what appears to be, a crawl space, which would mean the only potential for effective grounding would be near the main water line.

Jeff - I had also heard the 5 foot rule and in this case it is no where near that. The water enters the house in an adjacent room to where it’s connect to the plumbing.

Well if someone doesn’t chime in soon, I guess I’ll have to look up the reference. . .

lol…if you mean me chime in Jeff…lol…the reference on the distance is NEC Article 250.52(A)(1)

**250.52 Grounding Electrodes.
(A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe.

**A metal underground
water pipe in direct contact with the earth for 3.0 m
(10 ft) or more (including any metal well casing effectively
bonded to the pipe) and electrically continuous (or made
electrically continuous by bonding around insulating joints
or insulating pipe) to the points of connection of the
grounding electrode conductor and the bonding conductors.
Interior metal water piping located more than 1.52 m (5 ft)
from the point of entrance to the building shall not be used
as a part of the grounding electrode system or as a conductor
to interconnect electrodes that are part of the grounding
electrode system.

*Exception: In industrial and commercial buildings or
structures where conditions of maintenance and supervision
ensure that only quali.ed persons service the installation,
interior metal water piping located more than 1.52 m
(5 ft) from the point of entrance to the building shall be
permitted as a part of the grounding electrode system or as
a conductor to interconnect electrodes that are part of the
grounding electrode system, provided that the entire length,
other than short sections passing perpendicular through
walls, .oors, or ceilings, of the interior metal water pipe
that is being used for the conductor is exposed.

Thank Paul and Jeff…as always…great advice.

The 5-foot rule seems dubious now that plastic is allowed as underground water supply piping.

Not dubious…it only applies if the water pipe is Metal…and atleast 10’ within the ground…if not present…not used…

How can you tell how far into the metal pipe extends before it changes to plastic?

The plastic usually come all the way INTO the house and does not change out into the ground. So usually the location point is at the point of enterance of the water pipe systems.

Usually when plastic is being used it is again bought all the way into the dwelling…

Once place where the NEC accepts reality as part of factor in determining what is ‘OK’ and what is not. If you use the water pipe as your grounding electrode (which is required if you can determine -sometimes as an educated guess since you can’t see in the ground), then you still have to back it up with ground rod(s), ground plate, etc, etc… So the water pipe seems to never be your sole grounding electrode.

Now back to what the HI can do. Contact the water department, find out if they use only metal supplies or switched over any time.