NEC requirement for inhibitor

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ghelec

Member
Location
Texas
The electrical inspector in my hometown informed me the NEC requires inhibitor to be used on copper wire in meterbase and breaker panel lugs. We have always used on aluminum but not copper and I cannot find an article in the code book requiring it. The AHJ could not quote the article requiring it. Can someone give me the article #?
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I would ask him for the code reference but I doubt that he'll find one. The closest thing you'll find in the NEC is 110.14.
 

kwired

Electron manager
Location
NE Nebraska
Todays aluminum alloys do not require any either, many people use it out of old habits from when it was required.

There is nothing specifically addressing this in the NEC.
 

curt swartz

Electrical Contractor - San Jose, CA
Location
San Jose, CA
Occupation
Electrical Contractor
I posted a similar question about a year ago when a local inspector told me I had to use compound on copper conductors connected to aluminum lugs. My argument is the aluminum lugs are plated so oxidation should not be an issue. I contacted Square D and they told me no compound is required to copper or aluminum wire on their equipment. I contacted Ilsco and Burndy and they stated compound is part of the installations instructions for both copper and aluminum. I never got around to pursuing it more. but would like to.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Unless the lug is clearly labeled or it says in it's listing that it requires some sort of anti-oxidation inhibitor it's simply not required. Every AL/Cu lug I've ever seen could be used with either copper or aluminum conductors and no anti-ox. This goes back 110.14 in using the lug as per it's listing.
 

OTT2

Senior Member
Location
Orygun
From the 2011 UL White Book

..."Preliminary preparation of conductor ? Some wire connectors supply
instructions for the preliminary preparation of conductors, such as use of
conductor termination compound (antioxidant compound) or pre-twisting of
conductors, on or within the unit container.
Pre-twisting ? Some connectors may specify that conductors are to be
pre-twisted before assembly onto the connector.
Conductor termination compound ? Some connectors are shipped prefilled
with conductor termination compound (antioxidant compound). For
non-prefilled connectors, conductor termination compound may be used if
recommended by the connector manufacturer as preliminary preparation of
the conductor. Wire brushing of the conductor may also be performed if recommended.
Also see Conductor Termination Compounds (DVYW)."...

This is out of context but makes the point that others have previuosly stated.
110.14, 110.3(B)
 

ghelec

Member
Location
Texas
Thanks for all the replies. I will be calling the inspector for an inspection tomorrow and will see what he says when there is no inhibitor on the lugs.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
I posted a similar question about a year ago when a local inspector told me I had to use compound on copper conductors connected to aluminum lugs. My argument is the aluminum lugs are plated so oxidation should not be an issue. I contacted Square D and they told me no compound is required to copper or aluminum wire on their equipment. I contacted Ilsco and Burndy and they stated compound is part of the installations instructions for both copper and aluminum. I never got around to pursuing it more. but would like to.

Don't Ilsco and Brundy supply the compound with the connectors?
 
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