ECN Forum Forums Code Related Discussion NEC & other Code issues Contactor in a pull box

Drilled and tapped is nicer and more professional but you make less money. From all the jobs I've seen, 99.532% of all contractors use Tech screws to mount things in their pull boxes. Come to think of it, I guess it could possibly fall under grounding 250.8. A sheet metal screw is not allowed for grounding the frame of the contactor to the box.

I guess I'd like to kick in on this one. I think "tek" or "tech" screws are some sort of sheet metal screws either self taping or self threading and you may or may not have to drill a hole first. Bad way of mounting relays or any other component that has moving or vibrating features associated with it. If we look in Article 250.8 for grounding we need two full threads for acceptable grounding connections. Any J-box or "Hoffman" type box designed for mounting equipment contains a back plate feature and a back plate that is about 1/8th inch thick so equipment can be mounted on it with machine thread type screws. The back plate is raised so that the screw does not bottom out and also so it can be loosened, tightened or removed and replaced when the equipment is installed. If you are using any other method your standard is less than mine and probably most inspectors. Maybe a quick JIC standards class would help. As for pulling wires through the box in addition to the relay being properly mounted, I see no problem with that since it is permitted elsewhere in the code. See: 312.8 or 404.3(B)

I have never written 110.12 in 20+ years as an inspector but using "tek" screws to mount a relay would certainly be considered here.

Don't read more into 250.8 than is there. It says



There is nothing there about mounting equipment, even equipment that has to be grounded like the case of a washing machine. That is put together with sheet metal screws.

I also disagree that a contactor is going to cause that much vibration. 4 Tek screws in a 16 gauge box will not be coming loose. I wouldn't use them for a motor but that is not what we are talking about.

You can always argue it is not good workmanship and looks sloppy but I am not sure that rises to the level of a violation.

The OP doesn't give us enough information. If this relay is large enough it certainly will have a vibration if and when it its energized. Don't know if this is something that needs grounding either. This is pig work when they start installing equipment this way and I'm just the guy to use 110.12 and let them prove me wrong. I guess I better apologize for my standards but the NFPA 70 and NFPA 72 and the JIC Standards are minimum in my life.

Gentlemen:

IMHO, I did not quote any article, 110.12 (neat/workmanlike) is subjective and NJ does not recognize it. 110.13 may be a 'stretch', based on the interpertation.

I mentioned a 'list' of possibilities, and without info from Wewire, we are kind of shooting from the hip.

Professional craftsmanship, neat and workmanlike manner, etc., are considered 'gray areas'.

Another possibility? the tek screws projecting thru the back of the box, hindering mounting? Or the box being deformed? Or, the teks being pushed out by the box mounting? Or the teks protruding thru the back of the box which may cause injury to someone?

I'm sure if we all think hard enough, there are more possibilities! My judgement of the 'quality' of any install unfortunatley cannot be cited, although there may be something(s) that can be cited.

How do they mount boxes on steel studs?

Sorry bout that. I thought I made it clear that the only thing the inspector said was that is was not listed for that use, meaning that the box was not officially a contactor enclosure. I was jogging my memory since this was in late 90's when he called me on it. It was actually a 120V. relay that he was concerned about. I found a contactor and an approved box for this job I'm working on. It is interesting to see what issues come up here. Seems like most customers are looking for the
lowest price on jobs these days so doing things the absolute most bestest top quality time consuming way isn't
always a customer's priority. However, it does need to be a safe installation. That leaves lots of room for argument though. I guess if screwing a contactor in a box with tech screws is "pig work" then I plead guilty. :0

I have been watching this discussion, and being an inspector myself, I tend to agree with George on this one. My first thought is that I would want to see some documentation that by enclosing the relay in the enclosure it would not be in violation of 110.3(B). There may be heat issues here and ventilation and size could be a factor. In regards to using tek screws, they are not approved as an equipment grounding means. The relay base would have to be grounded or bonded per 250.8 and tek screws do not qualify. The fact that washing machines use sheet metal screws does not give any validity to this discussion. Washing machines are listed by a testing laboratory where as the relay in an enclosure is not listed. If you will look at 110.2 it state that equipment required or permitted by this Code shall be acceptable only if approved. Approval lies with the AHJ and the requirements are spelled out in 110.3(A). In lieu of doing their own testing most AHJ’s require listing and labeling. I often put the burden of proof on the contractor and that’s the way I would handle this one. If he could show me documentation where the relay and box are compatible, and he uses a 250.8 method of grounding or bonding, I would then accept it, but otherwise I would not.

Regards,

Tony

Tony, where does it say you can't use tek screws to mount hardware. 250.8 says "conductors and bonding jumpers".

Teks screws - good heavens, if you're going to try to paerse things, get the name right! "Teks" is a brand name / trademark of fastener made by ITW. That's TekS, not TeK.

I'll make the same point I made in the 'sheet metal screws for bonding' dispute: Using the correct fastener for the application that it was designed for is perfectly proper. It's only when you use the wrong fastener that you have problems. For attaching things to sheet metal, a Teks screw is perfectly proper - that's why the last code cycle modified the 'no sheet metal screws' rule to where I believe that the rule no longer applies to Teks screws - but that's another discussion.

There has certainly never been a rule against using Teks screws for uses besides attaching a bonding wire. Don't try to 'infer' this because think the box should be bonded to the metal wall, etc ... because these are the very screws that hols metal stud walls (light steel framing) together.

Now, if someone is using Teks screws to attach things to drywall, masonry, or wood, there's an issue.

As for the enclosure issue .... IMO all that matters is your fill factor, and that the enclosure do it's job.

We've become spoiled by our ability ot make custom products. One need not go far back in time - indeed, there are likely still some example around - where the 'factory made' items used the same enclosures as you might get from a supplier. Only later did the manufacturers start gettig fancy, with custom features like hinged doors, mounting flanges, and custom sizes.

Yet, this topic is the equivalent of disqualifying the winner of the Boston Marathon because it was found he wore "Cross trainng" shoes, rather than "running" shoes.