Metric Light Fixture Screws Wall Sconces

[hanklazard]

Many of the wall sconces are being provided with metric screws. Since they have matching finish lock nuts rethreading is time consuming and plus the fixture won't match the thumb screws. What size screws are metric light fixtures? I realized now I need an assortment of these.

 

[LarryFine]

I think they have a 7.892 x 31.769 thread.

Seriously, though (hey, it could happen), it seems that the only ones that matter are the 8-32s into the box.

 

[AC\DC]

Tell them to buy better lights.
Several American made residential lights.( now if you can afford is another issue)
this says M3.5x .6 for a 6-32 equivalent

Metric Bolt Conversion to Standard Bolt Conversion Chart

Fastener Chart | Metric Bolt Conversion | Common DIN Numbers for Metric Fasteners | Approximate Equivalency Chart Metric/US Roughly Equivalent US Bolt Materials | Diameter/Decimal/Metric Chart for Small Diameter Fasteners

www.raajsagarsteels.com

 

[LarryFine]

this says M3.5x .6 for a 6-32 equivalent

Of course, the conversion chart is for diameter, not pitch.

 

[hbiss]

Here you go

Amazon.com

-Hal

 

[LarryFine]

Here you go

Amazon.com

-Hal

If that was in response to my comment, I didn't mean to point out that pitch was missing from the chart, but that there are no matching/interchangeable threads.

 

[synchro]

Are any of these adapters suitable for what you want to do?

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1745

 

[LarryFine]

Are any of these adapters suitable for what you want to do?

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=1745

Now that's cool!

 

[OldBroadcastTech]

Of course, the conversion chart is for diameter, not pitch.

YES !
'American' is in threads-per-inch
Metric is in mm-per-thread

(just like 'metric mileage' is in liters-per-100 km)

 

[don_resqcapt19]

Many of the wall sconces are being provided with metric screws. Since they have matching finish lock nuts rethreading is time consuming and plus the fixture won't match the thumb screws. What size screws are metric light fixtures? I realized now I need an assortment of these.

Are the screws the ones that attach the luminaire to the box? Is the luminaire a listed product?
If the screws attach the sconce to the box I see that as a violation of 314.25.

314.25 Covers and Canopies.
In completed installations, each box shall have a cover, faceplate, lampholder, or luminaire canopy, except where the installation complies with 410.24(B). Conduit body enclosures shall be installed with a cover, lampholder, or device. Screws used for the purpose of attaching covers, or other equipment, to the box shall be either machine screws matching the thread gauge and size that is integral to the box or shall be in accordance with the manufacturer’s instructions.

The luminaire is "other equipment" in my opinion and covered by this rule.

 

[hbiss]

Many of the wall sconces are being provided with metric screws. Since they have matching finish lock nuts rethreading is time consuming and plus the fixture won't match the thumb screws. What size screws are metric light fixtures? I realized now I need an assortment of these.

Let's go back to the OP. I'm not understanding.

Fixtures are provided with a mounting bar or ring that mounts to the box with the usual 8/32s. Should be no problem there because there are only holes or slots and you use the box screws or provide longer ones.

Is he talking about that the fixture mounts to the bracket with metric screws or there are studs that use metric finish nuts that are provided by the manufacturer? Since they are provided, why do you need additional ones or have to rethread something?

Or is he doing something like trying to mount the fixture directly to the box and the metric screws provided obviously aren't 8/32? If so, I would return the cheap Chinese junk because re-tapping the box to some other thread is not allowed per 314.25.

-Hal

 

[hbiss]

If that was in response to my comment, I didn't mean to point out that pitch was missing from the chart, but that there are no matching/interchangeable threads.

No, not at all. It is just a gauge that you can use to find out what size and thread screw you have.

-Hal

 

[LarryFine]

Are the screws the ones that attach the luminaire to the box? Is the luminaire a listed product?
If the screws attach the sconce to the box I see that as a violation of 314.25.

The luminaire is "other equipment" in my opinion and covered by this rule.

Agreed, and there is no reason to use any screws other than real 8-32s.

 

[curt swartz]

Are the screws the ones that attach the luminaire to the box? Is the luminaire a listed product?
If the screws attach the sconce to the box I see that as a violation of 314.25.

The luminaire is "other equipment" in my opinion and covered by this rule.

99% of the fixtures (luminaires) sold are supplied with mounting screws slightly smaller than the normal 8/32. Depending on the box the screws can easily pull out.

I had a discussing about this with a UL rep at an inspectors meeting many years ago and was told they would look into it. Obviously they don't care.

I always tell my guys to never use the box mounting screws or wire connectors that are supplied with the fixture.

 

[BarryO]

99% of the fixtures (luminaires) sold are supplied with mounting screws slightly smaller than the normal 8/32. Depending on the box the screws can easily pull out.

Interesting. M4x0.7 is slightly smaller than 8-32, and the pitch is close.

 

[LarryFine]

Interesting. M4x0.7 is slightly smaller than 8-32, and the pitch is close.

That's what the poorly-fitting screws seem to be.

 

[hbiss]

That's what the poorly-fitting screws seem to be.

Interesting. I don't recall ever installing wall fixtures that mounted directly to the box. How does that work when there is the usual 4" round with the screws on the diagonal? What happens if there is a single gang ring on a 1900 or a 2"x4" single gang box? Always had a bar or round plate first because there is no telling what you are going to get.

At least with quality listed fixtures that is...

-Hal

 

[curt swartz]

Interesting. I don't recall ever installing wall fixtures that mounted directly to the box. How does that work when there is the usual 4" round with the screws on the diagonal? What happens if there is a single gang ring on a 1900 or a 2"x4" single gang box? Always had a bar or round plate first because there is no telling what you are going to get.

At least with quality listed fixtures that is...

-Hal

The fixtures include screws to mount the the bar/backplate to the box. These screws need to be 8-32 or should not be included at all.

The screws that are used to assemble the fixture parts can be any size as long as they are matching.

Pretty much all of even the the name brand expensive fixtures are now manufactured overseas and include the same crappy hardware.

 

[electrofelon]

At least with quality listed fixtures that is...

-Hal

Unfortunately "listed" doesn't mean much anymore

 

[hbiss]

The fixtures include screws to mount the the bar/backplate to the box. These screws need to be 8-32 or should not be included at all.

The screws that are used to assemble the fixture parts can be any size as long as they are matching.

Agreed, A bar/backplate needs to be provided and screws to assemble the fixture to the bar/backplate come with the fixture.

So, I don't know what the OP is talking about.

-Hal