Ground Lug hardware

[Brandon Loyd]

If I am using a mechanical lug, to attach my ground wire to a metal enclosure. Is it legal to attach the lug to the metal enclosure using a course thread Tek screw? Or is a 32 thread per inch machine screw always required?

 

[MarineTech]

250.8(5) Machine screw-type fasteners that engage not less than two threads or are secured with a nut.

The fasteners should be of the material and type that will not corrode in contact with the enclosure for the Location and atmosphere.

 

[infinity]

Here's the list from 250.8 that MT posted. You could use a thread forming machine screw but not a standard TEK screw.

250.8 Connection of Grounding and Bonding Equip-
ment.
(A) Permitted Methods. Equipment grounding conduc-
tors, grounding electrode conductors, and bonding jumpers
shall be connected by one of the following means:
(1) Listed pressure connectors
(2) Terminal bars
(3) Pressure connectors listed as grounding and bonding
equipment
(4) Exothermic welding process
(5) Machine screw-type fasteners that engage not less than
two threads or are secured with a nut
(6) Thread-forming machine screws that engage not less
than two threads in the enclosure
(7) Connections that are part of a listed assembly
(8) Other listed means