Article 110.14 covers this fairly well. However, I have been told that a non current carrying conductor (GEC) doesn't require an al/cu wirenut because there is no catalyst for galvanic action without current. If the article does apply to the GEC then you can't put an aluminum wire to a ground screw, you must pigtail it first??? Any help would be appreciated.
Al/Cu connections
- Thread starter fault
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- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Re: Al/Cu connections
Fault, welcome to the forum!
Also, a side note: A GEC stands for "Grounding Electrode Conductor", which is the actual conductor that runs between the service and the grounding electrode.
I think the acronym you're looking for is "EGC", Equipment Grounding Conductor. I'm not trying to pick on you here, I am only bringing it up because terminology is important here. In order for us to give the right answer to questions, it's important we're seeing the right question.
Fault, welcome to the forum!
That may be true, but 110.14 makes no bones about the functions of the conductor - only the material the conductor is constructed of.
Also, a side note: A GEC stands for "Grounding Electrode Conductor", which is the actual conductor that runs between the service and the grounding electrode.
I think the acronym you're looking for is "EGC", Equipment Grounding Conductor. I'm not trying to pick on you here, I am only bringing it up because terminology is important here. In order for us to give the right answer to questions, it's important we're seeing the right question.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: Al/Cu connections
Assuming that the box is steel, as is the ground screw, one could use the ground screw to attach an Al/Cu rated lug to the box. The Al EGC would terminate at the lug.
The addition of the lug falls through the box volume calculation, but it will make an impact by taking up a bit more space if the box is already crammed.
Assuming that the box is steel, as is the ground screw, one could use the ground screw to attach an Al/Cu rated lug to the box. The Al EGC would terminate at the lug.
The addition of the lug falls through the box volume calculation, but it will make an impact by taking up a bit more space if the box is already crammed.
Re: Al/Cu connections
Thanks for the help and the correction. I intended to type EGC not GEC but thankfully I still got my point across.I understand what the article says, it still seems like a reach. Adding a rated lug to the box is a good solution but we've all been there when spitting rubber nickles would be easier and more practical at times.However it still may be less of a hassle than trying to find out if a steel four square or a stell gound srew are rated for this use.
Thanks for the help and the correction. I intended to type EGC not GEC but thankfully I still got my point across.I understand what the article says, it still seems like a reach. Adding a rated lug to the box is a good solution but we've all been there when spitting rubber nickles would be easier and more practical at times.However it still may be less of a hassle than trying to find out if a steel four square or a stell gound srew are rated for this use.
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Re: Al/Cu connections
Under what conditions would you land a AL wire under a ground screw anyway?
Under what conditions would you land a AL wire under a ground screw anyway?
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: Al/Cu connections
Hey George,
The classic is the subdivision home built in the '60 - '70s that, for economic reasons, had Aluminum NM cable run. There was a world wide serious price hike in Copper that resulted in the next size larger Al NM being significantly less expensive.
I apprenticed during that period to a cost conscious contractor and put in some of that fated Al NM with my own two hands. Brrrr!
I've often wondered about those jobs and how they've weathered the years.
Suffice it to say, the NM EGC had to bond to the metallic enclosures that it entered. Hence, the use of ground screws with the Al EGC. . .ground screws as well as whatever other terminal was quick and readily available at the time.
Hey George,
The classic is the subdivision home built in the '60 - '70s that, for economic reasons, had Aluminum NM cable run. There was a world wide serious price hike in Copper that resulted in the next size larger Al NM being significantly less expensive.
I apprenticed during that period to a cost conscious contractor and put in some of that fated Al NM with my own two hands. Brrrr!
I've often wondered about those jobs and how they've weathered the years.
Suffice it to say, the NM EGC had to bond to the metallic enclosures that it entered. Hence, the use of ground screws with the Al EGC. . .ground screws as well as whatever other terminal was quick and readily available at the time.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: Al/Cu connections
That is a singularly curious colloquialism.
- Location
- Illinois
- Occupation
- retired electrician
Re: Al/Cu connections
Don
Galanic action only requires contact between the two metals and the presence of an electrolyte. Current is not required, and is actually produced as a result of the galvanic action.
Don
sandsnow
Senior Member
- Location
- Southern California
Re: Al/Cu connections
To counter the galvanic action or corrosion??? I think from the minearals in the water??
I'm not sure, just seen the water district install it.
Isn't that why they pump a small charge through metal water lines??
To counter the galvanic action or corrosion??? I think from the minearals in the water??
I'm not sure, just seen the water district install it.
Re: Al/Cu connections
I'm in a state subsidised, low income apartment complex that the owners are trying to convert to market housing. The place was built in 1970 and everything is Al NM. The other neat little hurdle I came across here was #12 Al on a twenty amp breaker. That one went from the local inspector to the state inspector who finally said there wasn't really anytrhing we could do because it was acceptable at the time the apartments were wired. He did want us to notify the owners in writing of the potential hazard.
I'm in a state subsidised, low income apartment complex that the owners are trying to convert to market housing. The place was built in 1970 and everything is Al NM. The other neat little hurdle I came across here was #12 Al on a twenty amp breaker. That one went from the local inspector to the state inspector who finally said there wasn't really anytrhing we could do because it was acceptable at the time the apartments were wired. He did want us to notify the owners in writing of the potential hazard.
hardworkingstiff
Senior Member
- Location
- Wilmington, NC
Re: Al/Cu connections
In steel underground storage tanks and steel piping there is a anti-corrosion (cathodic protection) system that is sometimes installed called an impressed current system. They impress a DC current onto the tank/piping, but you also have to install anodes. The tank/pipe is the cathode and the anodes give themselves up to protect the tank. Without the anodes, the current does not help.
macmikeman
Senior Member
- Location
- Planet macmikeman
Re: Al/Cu connections
If I ever run another alum ser #6 for a small range and I am mounting a flush outlet for it with a 4-11/16 box with a raised ring. Its a moot point though, since Home Depot came to Hawaii we can now get copper romex in larger sizes easy. Before that the local outfits only wanted to ship in alum for anything larger than #8. Shipping costs and all.
fishin' electrician
Senior Member
- Location
- Connecticut
Re: Al/Cu connections
What would be the electrolyte in an indoor metal switch box with an Al EGC connected to the steel? The moisture in the air?
What about at a panel where the Al NM EGC is run to the ground bar, are we supposed to insulate the bare Al conductor from touching the steel enclosure, or a Cu EGC in the same panel?
I have seen many aluminum bell boxes with steel fasteners for both the box itself and the device, that show no signs of corrosion.
Can Al conduit terminate at a steel box?
The more I look into this the more confusing it becomes. What's up with this sentence in 250.120(B)?
(B) Aluminum and Copper-Clad Aluminum Conductors. Equipment grounding conductors of bare or insulated aluminum or copper-clad aluminum shall be permitted. Bare conductors shall not come in direct contact with masonry or the earth or where subject to corrosive conditions. Aluminum or copper-clad aluminum conductors shall not be terminated within 450 mm (18 in.) of the earth.
Where subject to corrosive conditions it shall not come in direct contact with what?
What would be the electrolyte in an indoor metal switch box with an Al EGC connected to the steel? The moisture in the air?
What about at a panel where the Al NM EGC is run to the ground bar, are we supposed to insulate the bare Al conductor from touching the steel enclosure, or a Cu EGC in the same panel?
I have seen many aluminum bell boxes with steel fasteners for both the box itself and the device, that show no signs of corrosion.
Can Al conduit terminate at a steel box?
The more I look into this the more confusing it becomes. What's up with this sentence in 250.120(B)?
(B) Aluminum and Copper-Clad Aluminum Conductors. Equipment grounding conductors of bare or insulated aluminum or copper-clad aluminum shall be permitted. Bare conductors shall not come in direct contact with masonry or the earth or where subject to corrosive conditions. Aluminum or copper-clad aluminum conductors shall not be terminated within 450 mm (18 in.) of the earth.
Where subject to corrosive conditions it shall not come in direct contact with what?
- Location
- Massachusetts
Re: Al/Cu connections
Around here buildings wired in 1970 with AL NM would use 10 AWG AL for 20 Amp circuits, 12 AWG AL would be on 15 amp breakers.
I do not think they even made 14 AWG AL.
Was 12 AWG AL ever rated 20 amps?
Around here buildings wired in 1970 with AL NM would use 10 AWG AL for 20 Amp circuits, 12 AWG AL would be on 15 amp breakers.
I do not think they even made 14 AWG AL.
Re: Al/Cu connections
iwire,
They did it correctly where you come from. I know from the experience now that there was not a building code in the state of Connecticut prior to 1971. According to the state inspector it was permissible at the time to wire it the way they did.
I have never seen #14 Al Nm either.
iwire,
They did it correctly where you come from. I know from the experience now that there was not a building code in the state of Connecticut prior to 1971. According to the state inspector it was permissible at the time to wire it the way they did.
I have never seen #14 Al Nm either.
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