Junction box for pool light

[jholling]

Hi,
I am running the electric for my in the ground pool. I will have a light in the pool. My question is do I have to run a seperate conduit line to a junction box specifically for the light or is it ok to run the conduit back to my main juction/timer box? Givin that the main junction/timer box will be 24 inches above the max water line? If I need a Deck Box? Can that be mounted on the same 4x4 post?

Thanks,

Jed :confused:

[Wgoodrich]

Jed thanks for posting on the forum so others can learn. I already answered this for you but it should be help to others reading this forum. Again thanks

Jed

Depends on if this light is a low voltage light or 120 volt light.

I am taking it you have a 120 volt light.

Then it depends on if you have a wet niche underwater light or a dry niche underwater light.

Most are wet niche underwater lights 120 volt rated.

If this is what you have you must install an underwater light junction box at least 4' away and at least 8" above the water line. Remember your light comes with a cord. That cord must reach your underwater light junction box located at least 4' away and at least 8" above the water line. Be aware an underwater light junction box must be listed for use with an underwater light. This junction box may be metal or plastic but will contain a large green screw designed to accept an 8 awg copper bonding grid wire. The coduit you install between the underwater light and the underwater light junction box must be either brass or PVC. If PVC then you must install an 8 awg solid copper bonding grid wire in that conduit with that rubber cord connecting to a lug inside the wet niche light and the other end to that large green screw in that underwater light junction box. Longest cord I heard of for these lights are about 25 feet. This is often a problem to pull that rubber cord through a conduit. Keep that in mind.

The underwater light must be served by a dedicated branch circuit directly from teh main panel serving the house or pool shed designed for a pool. This circuit must be inside a conduit with a green insulated equipment grounding wire 12 awg minimum size. The only devices allowed in that circiut serving an underwater light is a switch, GFI protective device and underwater junction box.

Good Luck

Wg

[lfedericog]

Hi!

When I use low voltage luminaires do I have to use the junction box? What about the transformer, If I have a "house of machines" where panel, pumps, and other equipment are located, could I locate the the 120/12V transformer there? How then I supply 10 luminaires for example?

Could you explain me briefly how can I perform a low voltage luminaire circuit for the pool?

Thanks in advance.

Regards

[suemarkp]

Are these lights underwater lights or perimeter lights on the ground? If on the ground, how far away from the water's edge do you want to put them and how high? Pool lighting is a pain in the butt, and you don't get much relief by going low voltage.

[Ohm1]

Are these lights underwater lights or perimeter lights on the ground? If on the ground, how far away from the water's edge do you want to put them and how high? Pool lighting is a pain in the butt, and you don't get much relief by going low voltage.

I agree>>>with the pain in the butt part.

Ifed,

next time try to start a new tread (tread is almost 4 years old) . If you want you can start one, and we will take care of the rest.

[lfedericog]

Ohm1, Im going to take account your advice, but for this time Im going to continue in this thread.

SueMark, my luminaires are going to be underwater, wet niche, low voltage (12V).

We are designing an irregular shape pool and I will have too much lights. I will also have three structures in different places in my pool where I will put pumps, panelboards and other electrical equipment.

My question is about the low voltage circuit for this lights. I will have to use a 120/12V transformer (I guess!) and I dont know where must be located. (in the structures or in another place closer to lights).

Then, how much lights can I connect to this transformer circuit? Could you explain me a little bit how this circuit could be performed? Do I use junction boxes?


Thanks a lot!

[suemarkp]

You should read NEC 680.23 to learn about all the lighting requirements. You must buy a transfromer rated for swimming pool use. It could be in a 3R enclosure (means it can be outside and get rained on) or an inside only enclosure. NEC 680.24 explains the requiements for pool light transfromer enclosures. You size the transformer based on the number of watts you need to supply in pool lights. If you have (3) 50W lights, that is 150 watts. At 12V, you need 150/12 = 12.5 amp secondary rating of the transformer or larger, or one rated for 150W or more.

You must install these very much like a regular 120V light since they are wet niche. You need a conduit from each light to a pool light junction box which is 8" or more above high water level and 4" or more above the dirt or deck. It needs to be at least 4 feet away from the edge of the pool. I'd recommend PVC conduit for this. Since most low voltage pool transformers will not have a grounded secondary, you get to skip the bonding wire from the pool light junction box to each light (but only if the light niche is listed for low voltage ungrounded use, and it will probably be all plastic). They make the junction boxes in at least 1 and 2 light versions (so they wil have 2 or 3 conduit entries, respectively). If you have more lights than this, you'll need to find a larger box or install multiple boxes. Your transformer box will need to have enough conduit entry holes to handle the number of junction boxes you install plus the incoming conduit unless you diasy chain the light junction boxes and have only one conduit going to the lights.

You then run the light cord through the conduit from the pool niche to the junction box. Leave enough cord in the niche so the light can be floated up and pulled up onto the pool deck for relamping. When you install the light, you'll coil up this excess cord in the niche. Both ends of the light niche conduit need to be sealed with approved potting compound to keep water out of the conduit. You should be able to buy the light junction doxes and potting compound at a pool store.

I believe you need to run a green insulated ground from the breaker panel to the transformer box and then to the pool light junction box(es). Nothing else will connect to those grounds in the box, but it needs to be there to ground the brass cover. This wire must be at least #12 copper

[lfedericog]

Mark, thanks for your comments.

I have two doubts.

1) You tell about placing my junction boxes some distance above water level, but according to 680.24(A)(2)(c), I can use Flush deck boxes with low voltage lights (less than 15V) and the only restriction is that this box must be located 4ft from the inside wall of the pool.

Am I right?

2) I attach a picture to ilustrate a particular situation I have. The yellow figures are my lights. The box with a "2" is one of my structures (where I have panelboards and pumps). This section of the picture shows a "lazy river" inside the pool. I tag with "water" places that are going to be with water, "location 1" is a place outside pool where I can put my junction boxes 4ft form the pool walls, but what do you tell me about "location 2"? This is a place surrounded by water where some stones are going to be placed. But stones is not the problem, the problem is that this place is about 6 or 7 feet width (and in some places it is 3ft width). So I cannot accomplish the 4ft required for the distance between junction box and pool walls because for both sides it is surrounded by water.

Any comments will be appreciated.

[suemarkp]

Yes, you can use the flush deck boxes. These sections of the code are long, so I didn't give you every possible choice. However, think of wave action and eventually the potting compound will break down. Then, you'll get pool water in the junction box and connections may corrode. This isn't a safety thing, just a maintenance thing. My light junvtion box is about 12" above water level, and one day after a lot of "cannonballs" were done, the light kept tripping the GFCI. AFter a few days, it dried out and the lights worked again. This same thing won't happen to you, becuase with LV you don't use the GFCI on the secondary.

You don't have to put the boxes 4' away from the light -- it can be much further. The limitation will be on how long of a cord can you get with your LV light fixtures. If they can come with 100' long cords, then you could put the deck boxes about 100' away from the water's edge. If this hasn't been built yet, you could route the conduits under the pool and put them all at Location 1.

[lfedericog]

Ok, sounds good to locate junction boxes a distance permitted by the cord of the fixture but now I have another doubt. Keep in mind, the pool I am designing is not small.

The voltage drop between junction box and transformer (which I locate outside of structure as close as possible to junction boxes) is going to be big for short distances too.

For example, using %Vdrop = 4*L*I/(V*s)

where L is distance between junction box and transformer (in meters),
I is current, V is voltage and "s" is conductor area in mm2.

- Voltage is 12V

- Current is going to be in this case 300W/12V = 25 A, because a supply tree lights of 100W with a junction box.

- using a large conductor like #4 AWG, "s" is poing to be 27.1mm2.

For a short distance of 15 meters (as I already have in order to supply more than one junction boxes from one transformer, In fact I am thinking of 1200W transformers which give me four separate 12V circuits of 300W each one), voltage drop is going to be 4.6% which exceeds the 3% (this %3 is which I guess NEC permits).

I am not considering voltage drops in fixture-junction box conductor neither panelboard-transformer conductor as I think are low values. The higher voltage drop I thing occurs in transformer-junction box conductor.

Let me know if all this I am saying is ok.

My question is: with this scenario, do I have to locate transformers too close to junction boxes or use a big conductor (#2 AWG??) for junction box-transformer or there is another way to do this in order to minimize the voltage drop?

Thanks in advance,

[suemarkp]

The code has no requirements for voltage drop, just recommendations. You're not going to hurt a light with low voltage, it will just not be as bright, the color temperature will change to be more red (unless it a LED), and it will last longer if incandescent. I think you'll be fine with a 5% drop.

Many LV transformers have multiple voltage taps at 12, 13, and 14V. So look for a pool transformer with multi tapped outputs. Then, break up the lights into groups and use a smaller wire for each group so there are multiple sets of wires in the conduit (so the amps in each set of wires are lower than the total of 25A). Put the longest run on a 14V tap, the second longest run on the 13V tap, and the shortest run on the 12V tap. You may able to use #10 or #12 wires this way and just buy one large spool.

Running a single large wire will be cost prohibitive and you'll have problems terminating it and bending it.

[lfedericog]

Nice information!!

I have another doubt. What is the correct way to join the light cord with the conductor from the transformer inside the junction box?

I mean, is there a type of connector or device in order to supply (for example) cords of three different lights from say one single #4 circuit?

Thanks

[suemarkp]

This most likely won't work with wire as large as #4. Once you've hit that size, you ened to size junction boxes based on distance from one wall to the other, and it depends on whether the wire comes in and goes out the opposite wall or any other. The only way out of that is sometimes there is a label on the box saying "(3) #4 conductors" or something like that. Many times an LB type fitting will have a marking like that which is good, because most L type fittings violate the spacing minimums for conductors sized #4 and over.

If you use #6 and smaller wire, you still need to take conductor fill into account. A #6 wire needs 5 cubic inches. A #8 needs 3 cu in and a #10 needs 2.5. All grounds/bonds count as one wire of the largest size in the box. A pool junction box will have a little terminal block for grounding and equipotential bonding wires. Everything else you use wire nuts, split bolts, or other listed pressure connectors. I think a typical small split bolt could connect a #10 to a #6. You'd do this multiple times on a stripped section of the #6 and then tape it heavily so the insulation around the whole mass is as thick as what was originally on the #6 wire. If all you have is a #10 and three #12's, then a wire nut could easily handle this. If the transformer feed comes on #8, then you'll have to carefully check the wire nut box to see what you can combine with a #8 under one nut (and go for one of the larger sized ones).