Replacing rusted exterior junction box

[joelq]

Hi all -

I'm replacing one of my niche lights and as I'm doing that am going ahead and replacing the junction boxes which have rusted out. Here are pics of my situation. The left-most conduit (PVC) runs back to the pool equipment. The middle conduit (copper?) is the pool light, and the right-most conduit (copper?) is the spa light.

What has me puzzled is looking from below (pic) all conduit appear to be threaded into the junction boxes. How exactly does one undo these things, then install the new boxes in? Do I have to cut the conduit, then repair with couplers/repair sleeves (copper)?

Thanks!

 

[KenKasza]

The metal conduit is not copper. Copper pipe is used for plumbing. It is EMT (Electrical Metal Conduit). By the photos, it appears all your conduit is 1/2in.
First locate two new weather proof electrical boxes. These come in PVC or metal with 3/4in and/or 1/2in fittings. Some come with adapters (3/4 to 1/2) and plugs for unused openings.
Once you have the boxes and any needed adapters and plugs, you will need to obtain the proper fittings that will screw into the boxes and slip over the conduit. Yes, you will need to cut the conduits but don't do that until you first have all pieces and parts needed. You will want to test fit your new setup.
Seal all threaded fittings, caps, and slip joints with silicone sealant as you are assembling.

Be careful cutting the conduit. You do not want to damage the wires. Use a pipe cutter on the EMT. You can use the pipe cuter on the PVC as well. It just takes more effort. Hack saws are not desired. Too easy to cut the wires. Take your time.

There could be issues with NEC compliance.
- Height of boxes from the ground.
- EMT to Metal transitions
- Grounding/Bonding
Recommend checking with a local electrician if you have concerns.

I just replaced my rusted out metal boxes while installing a SWCG. I sourced all needed parts online from Home Depot and Lowes.

 

[joelq]

The metal conduit is not copper. Copper pipe is used for plumbing. It is EMT (Electrical Metal Conduit). By the photos, it appears all your conduit is 1/2in.
First locate two new weather proof electrical boxes. These come in PVC or metal with 3/4in and/or 1/2in fittings. Some come with adapters (3/4 to 1/2) and plugs for unused openings.
Once you have the boxes and any needed adapters and plugs, you will need to obtain the proper fittings that will screw into the boxes and slip over the conduit. Yes, you will need to cut the conduits but don't do that until you first have all pieces and parts needed. You will want to test fit your new setup.
Seal all threaded fittings, caps, and slip joints with silicone sealant as you are assembling.

Be careful cutting the conduit. You do not want to damage the wires. Use a pipe cutter on the EMT. You can use the pipe cuter on the PVC as well. It just takes more effort. Hack saws are not desired. Too easy to cut the wires. Take your time.

There could be issues with NEC compliance.
- Height of boxes from the ground.
- EMT to Metal transitions
- Grounding/Bonding
Recommend checking with a local electrician if you have concerns.

I just replaced my rusted out metal boxes while installing a SWCG. I sourced all needed parts online from Home Depot and Lowes.

Thanks so much for your reply! I reached out to a local electrician for some consultation - and perhaps just let them do the work.

Your confirmation that I do need to cut the conduit helps. I was wondering if an oscillating saw would be a good choice? But yes, a pipe cutter is probably to safest. I just don't know if I'll have enough room behind the conduit as it is right up against the fence. I'll check to see if there is enough play in the conduit to buy me some room for the pipe cutter.

Thanks, again! I'll report back on my progress.

 

[ajw22]

I was wondering if an oscillating saw would be a good choice?

Consider how easy or difficult it will be to pull new wires if you nick a wire.

Or see if you can pull the wires back below the cut line.

 

[joelq]

Quick update - I did some exploratory cutting with an oscillating saw and am quite sure I'm dealing with red brass. I would have thought copper due to the reddish color, but know that's not allowed for use as conduit. I also know that red brass conduit isn't readily available, at least around here. Any words of wisdom for those that have dealt with red brass conduit?

 

[Bill1974]

Red brass was not uncommon is older pools electrical conduit. My pool light used it before I replaced the light niche and used PVC conduit.

If you can pull back the wires, attach a steel wire snake to them before pulling them back to make it easier to pull the wire back. If your snake is on a reel, put it though all the new pieces as well before attaching to wire. Or attached a wire that you use as a snake.

Make note of the height of the current box and put a new one back at the same height or atleast what the code minimum is. Any higher and you will need to find a wire stretcher.

 

[Mdragger88]

Any higher and you will need to find a wire stretcher.

Lol
to the OP - this is not a thing!
it’s blinker fluid’s cousin

 

[ajw22]

Note that the metallic conduit and light niche can form the water bond on and older pool. Replacing the metallic conduit with PVC can compromise the water bond in the pool.

 

[KevMo]

There could be issues with NEC compliance.
- Height of boxes from the ground.

The NEC does not specify a minimum height above grade for outdoor outlets.

 

[ajw22]

The NEC does not specify a minimum height above grade for outdoor outlets.

If it is considered a pool light junction box then NEC 680.24 applies. Not less than 4 inches above the pool, or not less than 8 inches above the maximum water level.

 

[KevMo]

If it is considered a pool light junction box then NEC 680.24 applies. Not less than 4 inches above the pool, or not less than 8 inches above the maximum water level.

You are right. I did not consider the requirement if the box is connected to a conduit that extends directly to a forming shell or mounting bracket of a non-niche luminare. This requirement only applies to luminares thst operate over the low voltage contact limit, which is generally 48V or 50V depending on the AHJ. Low voltage luminare junction boxes can even be placed flush mounted on the deck if an approved potting compound is used to fill the box to prevent the entrance of moisture and the flush box is at least 4' from the wall of the pool. This was included in NEC 2020 and is still present in NEC 2023.

 

[KenKasza]

The NEC does not specify a minimum height above grade for outdoor outlets.

WOW....I just had to research it. You are correct. For exterior receptacles the NEC has a max height of 6'-6" for the first front and back exterior receptacles. Must be GFCI. I guess common sense must be applied when setting the height of exposed receptacles. Hmmmm.

Sorry this is a bit off topic.

 

[joelq]

Circling back to update the thread - given the difficulties of having to deal with the red brass conduit and worrying I would just cause other problems, I decided to forego replacing the junction boxes as the boxes themselves are in great shape - it was just the metal "fascia" that the cover screws onto that had rusted out. I'm assuming it's not made of the same material as the box itself?

There were "ears" that the rusted-out metal piece were riveted (?) to, so I just drilled holes into those, and attached a piece of aluminum sheet with stainless steel screws. I sheered off the screw heads to ensure enough clearance to the cover.

Are there any considerations around mixing of metals - the aluminum being in contact with whatever the junction box is made of?

 

[Bill1974]

Aluminum and stainless steel don't play well with one another, they will corrode. The Box is likely aluminum and/or zinc or some combination of the two. The metal piece you replaced was galvanized steel. This is a tough environment for metallic electrical enclosures.

If you want to make this last a little longer, replace the stainless steel screw with zinc plated steel ones or brass screws. Use counter sunk head screws and counter sink the aluminum plate (careful you don't strip the hole you need cover plate screw) so you don't need to cut off the heads of the screws.

Other than a complete redo you are just trying to buy time and there is no quick fix either.

 

[joelq]

Aluminum and stainless steel don't play well with one another, they will corrode. The Box is likely aluminum and/or zinc or some combination of the two. The metal piece you replaced was galvanized steel. This is a tough environment for metallic electrical enclosures.

If you want to make this last a little longer, replace the stainless steel screw with zinc plated steel ones or brass screws. Use counter sunk head screws and counter sink the aluminum plate (careful you don't strip the hole you need cover plate screw) so you don't need to cut off the heads of the screws.

Other than a complete redo you are just trying to buy time and there is no quick fix either.

Thanks so much for this! The corrosion risk was exactly what I was wondering about. I'll replace the stainless steel screws with what you described.

And yes, I'm really just trying to kick the can down the road and delay a complete redo.