bonding each underwater light niche

Status
Not open for further replies.
R

rusty123

Member
Location
Lemoore, CA
I need to install 16 each new underwater fixtures in an existing underground concrete pool. Since the each metal niches need to be bonded to the grid I'm looking for ways to ease the pain. My plan is to chip away the concrete wall to expose the rebar at "one" niche location, connect a #8 from the niche to the rebar for the bond and to an existing wall J box. Then run a perimeter #8 through existing metal conduits and wall J-boxes with jumpers down to each of the other niches?
 
What you're proposing sounds like it would meet the intent of the NEC for bonding. You may want to specify a continuity test upon completion measuring from the bonding lug at the pump motor to each nice and to every metal object within 5' horizontal of the water's edge and 12' vertically.

Is this pool for training or functional test of powered systems which utilize voltage and frequency other than that used by the pool pump?
 
Are they excavating around this pool to install the 16 new light fixtures?

Are the existing conduits being used for some other original purpose and if so what purpose?
 
If this is an electrical job on Navy property (Federal property) then why isn't the BOSC handling the job in-house? If this is a BOSC electrician and the job is being subbed out, then why ask questions here?

Wouldn't the electrician be the best one to determine the method?

...anyway, knowing dry-niche or wet-niche is a start.

Article 680 is your friend, along with 250.122.
 
We install LED nicheless lights. We have not installed a traditional wet niche light in over 8 years.

The LED lights we install use, utilize an 1.5" PVC pipe. Drill out with a 2" core bit so it finishes 4" below the water level. The placement is similar to fiber optic in pool lighting we did in the early 90's. Closer to the surface provides better reflecting value-or brighter lighting.

No bonding or grounding on these lights. 12V with a small lens flush with the wall. A female 1.5" fitting allows the light fixture to thread in.

We built a large commercial pool (80x40) 4 years ago. We installed 30w white LED lights (max available even now) on both long sides. I believe 8 (not sure maybe more) on each side. Each side operated independently. The finish in the pool was a white base which helps with the light illumination. Lit up like Times Square.

We install these models on renovation projects because of ease of installation and less of a headache trying to bond. I'm pretty certain also the wet niche lights must be at least 18" below the water as per NEC.

You will need multiples of lights to prevent shadows so maybe a little more $ for the lights, but you save time and aggravation on the install.

Don't waste your time with regular wet niche lights. A good core drill and bits that go through rebar are a lot easier than busting out a wall trying to find rebar and then setting a niche and making it waterproof!
Been there, done that. This is the way to go.
 
cuba_pete said:
Good call...LEDs and low voltage were born for wet locations.
Click to expand...

Has nothing to do with that. When two dissimilar metals are in contact, the solution becomes the electrolyte and the more reactive metal becomes the consumed electrode. Pool water is far from totally pure and would likely be electrolytic enough to cause gradual damage.
 
Any copper to steel contact with an electrolite will make the steel corrode quickly

Any copper to steel contact with an electrolite will make the steel corrode quickly

Electric-Light said:
Has nothing to do with that. When two dissimilar metals are in contact, the solution becomes the electrolyte and the more reactive metal becomes the consumed electrode. Pool water is far from totally pure and would likely be electrolytic enough to cause gradual damage.
Click to expand...
I've seen steel corrode and stain the pool within months. Even stainless steel will stain if there are any chlorides (chlorine or salt) in the water. I have seen 316 SS corrode 304 SS in a salt water pool. Either the metals must not touch, or the water must not touch the metals to prevent corrosion. Both of these solutions are very hard to accomplish in a pool. (I like the idea of fiber-optic lighting even though I have never used it.)
 
david said:
Are they excavating around this pool to install the 16 new light fixtures?

Are the existing conduits being used for some other original purpose and if so what purpose?
Click to expand...
yes we excavated the outside of the pool wall at each light location and found the existing conduit. We will empty the pool, core drill through the 12" thick concrete walls, chip out the back side to expose the rebar, attached # 8 from the rebar to the lug inside the niche, attach # 8 from same lug and run to the wall J box and attached to an existing lug inside the boxes. The niche will be set in fast drying hydrolic cement. Once installed we test grounding wire etc...
 
Metallic items in contact with the pool can most definitely corrode.

Salt water pools, are in actuality, utilize pure salt as a mean to produce chlorine, namely sodium hypochlorite-basic household bleach.

Not only is chlorine in itself is corrosive, so is salt. It can also damage and deteriorate cement based products such concrete decks and mortar joints.

Stainless ladders and rails are affected as well.

Currently we are renovating a pool about 35 years old. The wet niche lights have stainless niches. The bond set screw is stainless. The "lug" on the niche is brass. The bond wire, of course, is copper. The lug on 1 niche is corroded from the chems. The pool recently had a chlorine generator system (salt) installed. Two dissimilar metals do have an unfavorable reaction when exposed to moisture.

Now we are faced with the challenge to properly bond these niches.

Incidentally, the original bond wire in the niche was a #10 insulated solid wire. We will change to a #8 wire and use potting compound.
 
Electric-Light said:
Has nothing to do with that. When two dissimilar metals are in contact, the solution becomes the electrolyte and the more reactive metal becomes the consumed electrode. Pool water is far from totally pure and would likely be electrolytic enough to cause gradual damage.
Click to expand...

Well, yeah, it actually has a lot to do with NEC and OSHA...so, yeah...there's that.

The bonding requirements aren't put in place by the NEC to "prevent electrolysis".
 
Is the existing conduit brass, if so that is allowed as the bonding conductor, if not brass I don't believe metallic conduit is allowed to feed a niche. The lug on the inside of the niche is for a bonding condutor pulled with the lamp feed, and encapsulated after termination. Typically there is also a lug on the exterior of the niche for a bonding conductor installed as part of the equipotential grid
 
eds said:
Is the existing conduit brass, if so that is allowed as the bonding conductor, if not brass I don't believe metallic conduit is allowed to feed a niche. The lug on the inside of the niche is for a bonding condutor pulled with the lamp feed, and encapsulated after termination. Typically there is also a lug on the exterior of the niche for a bonding conductor installed as part of the equipotential grid
Click to expand...

If the brass conduit is visible at the deck/junction box, I would attach a bond wire to that and also to the grid if it's available.

I've been servicing pools since the early 80's. Of course at that time pools lots of pools were built in the 60's and 70's. A few from the 50's. Some of them used 1/2" steel conduit on the pool lights. Trying to replace a light fixture was almost impossible as the cord would swell up over time and the conduit would rust and scale inside. They would also completely rot creating a leak. Serviceman had tricks to free the cord in the conduit sometimes compressed air with some type of oil.

There were also plenty of light niches with brass conduit. They too would eventually corrode and cause water loss.
In the last 30 + years or so plastic conduit has been the choice. Usually 1".
The wet niches are available in stainless steel and PVC.

The niches do have a bond lug on the inside and the backside of the niche body. The inside lug must have a potting compound the encapsulate the connection. Inspectors want that. Some also wanted potting compound on the backside. That bond wire connected to the common grid which hit the steel rebar on a concrete pool or the steel panel on a vinyl pool.

The inside bond wire that shares the light cord conduit, connected to a lug on the deck box which in turn connected to the common grid. That bond wire has been an insulated type. NOTE: Lots of older pool had brass junctions boxes flush with the patio. Code requirement now is to have the deck box above the water level.

We have not installed wet niche lights for about 8 years. We install nicheless LED lights that utilize either a 2" or 1.5" PVC pipe. It depends on the manufacturer. No bonding, no grounding, 12V lights. Savi lights owned by Zodiac/Jandy pool products is our brand used commonly.

We do however, have to deal with older lights on renovation projects (as we are presently). Bonding those niches can be a challenge.
Making sure they are bonded is paramount and we will test to ensure this.

Anytime I have the opportunity and the customer has the $, we will eliminate the wet niches and install the LED's.
 
Status
Not open for further replies.
Top