Non UL approved, homemade, grounding or bonding..Legal?

Status
Not open for further replies.

Mule

Senior Member
Location
Oklahoma
Ok, a old habit of mine. When I need to ground or bond an enclosure, I drill a clearance hole for a 1/4-20x 1" bolt in the bottom of the enclosure. I install the bolt up through the bottom of the enclosure and thread a hex nut onto the bolt inside the enclosure, which is wrenched down really tight. Then a second nut goes on to use to tighten conductors down with via "L" lugs, crimp lugs, fender washers or whatever I think is needed.

I know Im a hillbilly, but is this acceptable?
 

raider1

Senior Member
Staff member
Location
Logan, Utah
Take a look at 250.8 in the 2008 NEC. Specifically 250.8(A)(5).

250.8 Connection of Grounding and Bonding Equipment.
(A) Permitted Methods. Grounding 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

Chris
 

Mule

Senior Member
Location
Oklahoma
Take a look at 250.8 in the 2008 NEC. Specifically 250.8(A)(5).



Chris

Thanks I'll read into that, so, looks like #5 would cover me.......Looks like they would dictate the size of the machine screw. In fact, I've always understood that 1/4" and above are considered bolts, and below 1/4" are considered machine screws ie: 10-32,10-24,8-32,6-32,4-40......
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
I would rather see the surface of the lug in contact with the enclosure instead of using the bolt and nut as the conductor between the lug and the enclosure. I don't see bolts and nuts in the list of permitted EGCs.
 

celtic

Senior Member
Location
NJ
Ok, a old habit of mine. When I need to ground or bond an enclosure, I drill a clearance hole for a 1/4-20x 1" bolt in the bottom of the enclosure. I install the bolt up through the bottom of the enclosure and thread a hex nut onto the bolt inside the enclosure, which is wrenched down really tight. Then a second nut goes on to use to tighten conductors down with via "L" lugs, crimp lugs, fender washers or whatever I think is needed.

I know Im a hillbilly, but is this acceptable?

I go the "extra mile" and tap the hole.
 

hillbilly

Senior Member
Ok, a old habit of mine. When I need to ground or bond an enclosure, I drill a clearance hole for a 1/4-20x 1" bolt in the bottom of the enclosure. I install the bolt up through the bottom of the enclosure and thread a hex nut onto the bolt inside the enclosure, which is wrenched down really tight. Then a second nut goes on to use to tighten conductors down with via "L" lugs, crimp lugs, fender washers or whatever I think is needed.

I know Im a hillbilly, but is this acceptable?

From one "Hillbilly" to another, sounds OK to me, although I usually bolt the lug directly to the enclosure after removing some paint.

steve
 

makalroy

Member
I would rather see the surface of the lug in contact with the enclosure instead of using the bolt and nut as the conductor between the lug and the enclosure. I don't see bolts and nuts in the list of permitted EGCs.

Why?
The bolt seems to be the strongest and least resistive link in a chain that consists of a wire, a lug, a bolt, and an enclosure.
 

Buck Parrish

Senior Member
Location
NC & IN
Why?
The bolt seems to be the strongest and least resistive link in a chain that consists of a wire, a lug, a bolt, and an enclosure.

It's the washer, it has cheap galvanized "stuff" on it. It can coarrode and you will loose your grounding connection.

It's like we we're talking about on "man hole covers thread". It just depends on the enviroment.
That's why a ul listed connection is the preferred, yet more exspensive method.:D
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
That's why a ul listed connection is the preferred, yet more exspensive method.:D
Then you have never looked at the UL Listed connection inside of a Hoffman (TM) enclosure.
The stuff Hoffman includes is a 1/4 bolt and (2) Keps nuts (the ones with the built star washer).
1) Put the bolt through the hole
2) Fasten with a Keps nut (no paint removal necessary)
3) Put lug over bolt
4) Fasten with Keps nut
 

newenergy

Member
I think "keps you from losing it" was a joke.

The trivia is that the "kep" comes from ShaKEProof, because keps is a trademark of ITW (Illinois Tool Works) Shakeproof.

Blame google.

Now to go from annoying to stupid?

Is there something wrong with tech screws or self tapping screws?
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Is there something wrong with tech screws or self tapping screws?

No, yes, maybe.

I think of a TEC screw as a 'non-tapered' self-drilling screw. It is not the same creature as either a self-tapping screw, which requires a pilot hole, or a self-drilling sheet metal screw, which has a very large thread pitch.

The NEC does not prevent you from using self-drilling and/or self tapping screws as long as they 'cut' the correct threads as referenced by JohnJ0906.
 

newenergy

Member
Cool, thanks.

I have been using some thread forming machine screws that come with the grounding lugs I get. They have very fine threads and I'm sure they meet the requirement.

The TEC screws, which I have used as well :(, seem to be no good for this.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
I think Don G. raises a great point. Looking at 250.118, I don't see a bolt and nut (installed as Mule details in his OP question) as a possible EGC that I can use as a field installer.

When Jim Dungar brings up the Hoffman box ground lug that is built in a very similar manner to Mule's, the difference is that the Hoffman box is a manufactured assembly.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
When Jim Dungar brings up the Hoffman box ground lug that is built in a very similar manner to Mule's, the difference is that the Hoffman box is a manufactured assembly.
I don't know about that. The parts are shipped loose in a bag. They may be used on the door and/or the back panel. If you have a double door enclosure or if you purchase an interior door kit, you do not get enough parts to bond everything. There are no specific assembly instructions included.

But my inclusion of this method was to address the comment that a UL Listed assembly is a more 'expensive'.
 
Status
Not open for further replies.
Top