Recounting a security light on the side of the house that has been down for a while. The housing of the light looks like some sort of cast pot-metal clamps to a 1.6" metal arm.
I need 2 bolts to hold the clamp in place and enter into pre-threaded holes in the light housing.

Question: Do I need to use stainless steel bolts to keep the bolts from croading away at the metal housing ?

Stainless is preferable and will last longer, but typically just zinc coated are used.

On Sun, 15 Mar 2020 08:55:40 -0700 (PDT), trader_4
wrote:

Stainless is preferable and will last longer, but typically just zinc coated are used.

That is why it is so hard to get the covers off or remove the
luminaire later. If this is not considered disposable, use stainless
screws everywhere you want it to come apart later.

On 3/15/2020 11:37 AM, wrote:
Recounting a security light on the side of the house that has been down for a while. The housing of the light looks like some sort of cast pot-metal clamps to a 1.6" metal arm.
I need 2 bolts to hold the clamp in place and enter into pre-threaded holes in the light housing.

Question: Do I need to use stainless steel bolts to keep the bolts from croading away at the metal housing ?


Stainless will help but even they eventually rust over time. I use zinc
coated and spray them wit lithium grease before screwing them in. I very
seldom, if ever, have a problem when removing them to do work if needed.

Through trial and error I have determined that the threads are 7mm, I can find that size in zinc, but not in stainless.

The bolts come through the top of flange of the light casing and are exposed above.

Is there something I can cover them with to protect them from the elements ?

Should I just tape them up real well w/blk electrical tape ?

Where can I find 7mm stainless ?

Thanks to everyone that contributed.

On 3/15/2020 4:12 PM, wrote:
Through trial and error I have determined that the threads are 7mm, I can find that size in zinc, but not in stainless.

The bolts come through the top of flange of the light casing and are exposed above.

Is there something I can cover them with to protect them from the elements ?

Should I just tape them up real well w/blk electrical tape ?

Where can I find 7mm stainless ?

Thanks to everyone that contributed.


Don't think you will McMaster does not list M7 in stainless and if they
don't have them doubt anyone else will.
https://www.mcmaster.com/screws

On 3/15/2020 3:12 PM, wrote:
Through trial and error I have determined that the threads are 7mm, I can find that size in zinc, but not in stainless.

The bolts come through the top of flange of the light casing and are exposed above.

Is there something I can cover them with to protect them from the elements ?

Should I just tape them up real well w/blk electrical tape ?

Where can I find 7mm stainless ?

Probably not going to; Fastenal doesn't have anything in either cap
screw nor machine screw in SS in 7M -- and da-d little 7mm of any material.

I'd probably retap to something sensible like 1/4-18 and then use brass
or bronze, SS is likely to set up galvanic reaction anyway. Unless it's
really heavy or subject to some other loading issues, nylon would work.

Cover the top side with good dab of silicon; surely it's under an eave
or something and not in direct weather anyway?

--

No, its mounted on a poll. Very exposed !

On 3/15/2020 3:48 PM, dpb wrote:
....

I'd probably retap to something sensible like 1/4-18 and then use brass
or bronze, SS is likely to set up galvanic reaction anyway.Â* Unless it's
really heavy or subject to some other loading issues, nylon would work.
....

Actually, M7 is too big for 1/4 (and the 18 above was a typo for 28)...

A drill size F (0.2570) for 5/16-18 NC or I (0.2720) for 5/16-24 NF
would be next.

--

On 3/15/2020 4:04 PM, wrote:
No, its mounted on a poll. Very exposed !

It's also apparently much bigger/heavier than I was thinking about w/o
actually computing -- I was thinking of just a little eave cover
spotlight thingie.

See followup -- it's closer to 5/16" than 1/4".

--

Install per instructions. The light will fail before needing to be replaced.

On 3/15/2020 4:12 PM, wrote:
Through trial and error I have determined that the threads are 7mm, I can find that size in zinc, but not in stainless.

The bolts come through the top of flange of the light casing and are exposed above.

Is there something I can cover them with to protect them from the elements ?

Should I just tape them up real well w/blk electrical tape ?

Where can I find 7mm stainless ?

Thanks to everyone that contributed.


Caulk.

On 3/15/2020 4:12 PM, wrote:
Through trial and error I have determined that the threads are 7mm, I can find that size in zinc, but not in stainless.

The bolts come through the top of flange of the light casing and are exposed above.

Is there something I can cover them with to protect them from the elements ?

Should I just tape them up real well w/blk electrical tape ?

Where can I find 7mm stainless ?

Thanks to everyone that contributed.


You're overthinking it. Use the zinc, lubricate the threads, screw and
tighten, caulk the heads, done. Go have a beer.

On Sun, 15 Mar 2020 16:26:08 -0400, Ed Pawlowski wrote:

On 3/15/2020 4:12 PM, wrote:
Through trial and error I have determined that the threads are 7mm, I can find that size in zinc, but not in stainless.

The bolts come through the top of flange of the light casing and are exposed above.

Is there something I can cover them with to protect them from the elements ?

Should I just tape them up real well w/blk electrical tape ?

Where can I find 7mm stainless ?

Thanks to everyone that contributed.


Don't think you will McMaster does not list M7 in stainless and if they
don't have them doubt anyone else will.
https://www.mcmaster.com/screws

I can get 7mm stainless at my local ace hardware but maybe it is just
a Florida thing.

On 3/15/20 10:37 AM, wrote:
Recounting a security light on the side of the house that has been down for a while. The housing of the light looks like some sort of cast pot-metal clamps to a 1.6" metal arm.
I need 2 bolts to hold the clamp in place and enter into pre-threaded holes in the light housing.

Question: Do I need to use stainless steel bolts to keep the bolts from croading away at the metal housing ?

There are anti seize compounds but I don't know if they're any
better than good old grease.

On 3/15/2020 8:44 PM, wrote:
On Sun, 15 Mar 2020 16:26:08 -0400, Ed Pawlowski wrote:

On 3/15/2020 4:12 PM, wrote:
Through trial and error I have determined that the threads are 7mm, I can find that size in zinc, but not in stainless.

The bolts come through the top of flange of the light casing and are exposed above.

Is there something I can cover them with to protect them from the elements ?

Should I just tape them up real well w/blk electrical tape ?

Where can I find 7mm stainless ?

Thanks to everyone that contributed.


Don't think you will McMaster does not list M7 in stainless and if they
don't have them doubt anyone else will.
https://www.mcmaster.com/screws

I can get 7mm stainless at my local ace hardware but maybe it is just
a Florida thing.


They have them at my local Ace and a local family owned hardware store
that puts HD and Lowes to shame, with exception to lumber.

Thanks, I'll chk Ace tomorrow.