Saltwater eating away pool light screw??

[Madty]

Yes, the original was brass- it wasn't long enough to reach into the female part of the niche. I bought a longer stainless steel screw. It was at time hard to screw in so threads may have been stripped a little. I need to get another brass screw. That is probably why much of my white light cover is getting orange rust stains all over the top where the screw goes. Even on the inside- I thought it was the salt, maybe it was the type of screw I used. When I saw the threads were gone, I mean all that's left is a real skinny part of a screw- weird. Does anyone know the standard size screw that goes in a niche? I remember it was metric.

[sevver]

Two dissimilar metals can react to each other, maybe that is what is going on, I have no idea if brass and stainless react though, that is a question for the chemists in here.

What I do know is this, brass is used in alot of underground water service applications because it is pretty stable and will last literally decades. And most of the reasons for watermain breaks are from electrolosis, where different metals or minerals react to the metal, I have seen the bolts completely rotted out of fittings, and all you had to do to fix the leak was replace the bolts and retighten.

Basically if brass was in there I would definately replace it with brass. I have no idea where you would find it though, I would imagine that Ace Hardware would have them, they have thos little boxes with all kinds of odd stuff in there, Home Depot has one of the saddest nut and bolt selection in the world, as does Menards. Lowes is not bad, but Ace never lets me down.

[Poolsean]

The niche is usually stainless steel and the face plate, plastic or chrome plated brass.

Make sure that your equipment are all bonded together with the green bonding wire. That can eat away metals too.

[dawndenise]

Funny thing about screws...we have had 2 Pentair SAm lights in our new pool for just under 2 months now. I can feel that the screw heads are already corroding to some extent and this was before we added salt for the SWG.

In throwing away the boxes the lights came in, I discovered a small plastic still-sealed packet in each box containing a screw and washer . The packet is labelled, "Attention Installer - Caution!"

This is the wording on the package: This extra stainless steel pilot screw has been provided for use on new pool construction only. When replacing a light fixture in an existing niche, you must use the bronze screw that is supplied with the light fixture. This pilot screw is a key component of the grounding path for the light fixture. To maintain the electrical connection, always use the correct pilot screw and tighten it securely.

I called our electrician who wired everything up and asked if the stainless steel screw in the package should have been used for our application when the plaster crew anchored the light and his reply was "yes." I didn't ask him why there should be any difference in screws depending on how old the installation was.

In any event, we'll be switching out the screws before using the lights again! Hopefully, the stainless steel screw will not deteriorate in the saltwater.

[mshumack]

, "Attention Installer - Caution!"

This is the wording on the package: This extra stainless steel pilot screw has been provided for use on new pool construction only. When replacing a light fixture in an existing niche, you must use the bronze screw that is supplied with the light fixture. This pilot screw is a key component of the grounding path for the light fixture. To maintain the electrical connection, always use the correct pilot screw and tighten it securely.

I also noticed that warning on the extra screws that came with the two SAM lights I installed. I can't find any info on the reasoning behind this. What is the difference between a new and existing installation that would necessiate the need for different screws. The lights came with screws already mounted in the fixtures so I just used those - and left the spare SS ones in the bag. I didn't look closely at the time of installation, but I guess the screws that were in the fixture were the brass ones (they weren't brass colored though).
PentairTech are you out there?