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Thread: 120 volt underwater pool lights

  1. #1
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    120 volt underwater pool lights

    Currently at our high school we have 300 watt 120 volt underwater lights in both pools. The high school was built in the 70's. They are dry niche fixtures, protected by GFCI circuit breakers, accessed by the pool basement equipment area. For safety sake, I would like to convert these to 12 volt lamps. I have found 240 watt, 12 volt lamps and the needed transformers. The lamps will draw about 21 amps each. Also, the GFCI will offer no protection on the secondary side (12 volt) of the transformer, correct? Will this change make our pools any safer? What do you guys think?

  2. #2
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    Are any metallic shells bonded to the equipotential bonding network? That is likely your biggest potential safety improvement if it is not already done.

    Converting the lamp to low voltage with the high voltage still at/near the luminaire probably doesn't lessen potential shock hazard by all that much.

  3. #3
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    Quote Originally Posted by kwired View Post
    Are any metallic shells bonded to the equipotential bonding network? That is likely your biggest potential safety improvement if it is not already done.

    Converting the lamp to low voltage with the high voltage still at/near the luminaire probably doesn't lessen potential shock hazard by all that much.
    The shells are bonded to the equipotential network. The high voltage/ transformers would be mounted several feet away from the fixtures.

  4. #4
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    Quote Originally Posted by starsandstripes View Post
    The shells are bonded to the equipotential network. The high voltage/ transformers would be mounted several feet away from the fixtures.
    JMO, but I don't think it makes a very significant difference in any risk, getting the higher voltage further away from the pool users does still give some improvement though.

    If spending $$ on transformers and specialty lamps anyway - maybe look into higher efficiency LED's? (no idea what is out there for this application)

  5. #5
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    Quote Originally Posted by kwired View Post

    If spending $$ on transformers and specialty lamps anyway - maybe look into higher efficiency LED's? (no idea what is out there for this application)
    I agree, LED is the way to go these days.

  6. #6
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    Quote Originally Posted by starsandstripes View Post
    Currently at our high school we have 300 watt 120 volt underwater lights in both pools. The high school was built in the 70's. They are dry niche fixtures, protected by GFCI circuit breakers, accessed by the pool basement equipment area. For safety sake, I would like to convert these to 12 volt lamps. I have found 240 watt, 12 volt lamps and the needed transformers. The lamps will draw about 21 amps each. Also, the GFCI will offer no protection on the secondary side (12 volt) of the transformer, correct? Will this change make our pools any safer? What do you guys think?
    The gfci will not offer protection on the secondary side however the transformer must be suitable for use for pool equipment.

    I found this article years ago but don't know where it came from. I am sure I can search it and find it if I wanted to...

    There are low-voltage lighting power units that are marked “For Use withSubmersible Fixtures or Submersible Pumps.” In this case, a special transformeris used that complies with the requirements in 680.23 for underwater luminairesinstalled below the normal water level of the pool. This transformer isspecifically listed for this use and is an isolated winding type transformerwith an ungrounded secondary similar to the low-voltage landscape lightingtransformer, as required by 411.5(B). The low-voltage pool lighting transformerhas one additional feature in its design. It has a grounded metal barrier orshield between the primary and the secondary. This metal barrier or shield preventsa direct internal short between the primary and the secondary of thetransformer. If a short does occur on the primary side, it will short to themetal shield and the primary overcurrent protective device will operate. If ashort develops on the secondary side to the shield, the secondary overcurrentprotective device, if provided, will operate. If there isn’t a secondaryovercurrent protective device and the primary is providing protection throughthe transformer, the primary device should operate.

  7. #7
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    Quote Originally Posted by Dennis Alwon View Post
    The gfci will not offer protection on the secondary side however the transformer must be suitable for use for pool equipment.

    I found this article years ago but don't know where it came from. I am sure I can search it and find it if I wanted to...
    Thanks for the info on the transformers. I have not had any luck yet finding 12 volt LED lamps with comparable lumens.

  8. #8
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    Maybe I can help you find a suitable replacement 12V or 24V LED pool light if you have the model number of the original light. For 12VAC lights, you need a pool/spa transformer (with a grounded metal barrier between pri/sec windings). Unfortunately for 12V or 24V DC lights, no one makes a power supply with the same ratings as the 120V pri/12V sec pool/spa transformers, and DC LED underwater lights are more common than AC LED underwater lights.

  9. #9
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    Quote Originally Posted by starsandstripes View Post
    Currently at our high school we have 300 watt 120 volt underwater lights in both pools. The high school was built in the 70's. They are dry niche fixtures, protected by GFCI circuit breakers, accessed by the pool basement equipment area. For safety sake, I would like to convert these to 12 volt lamps. I have found 240 watt, 12 volt lamps and the needed transformers. The lamps will draw about 21 amps each. Also, the GFCI will offer no protection on the secondary side (12 volt) of the transformer, correct? Will this change make our pools any safer? What do you guys think?
    I doubt the original lights are wired with #10; 21A isnt going to fly on #12 or #14... or are you rewiring the entire thing?

    Istm that modern LED lights would not need to be near the same wattage as the old lights to get the same lumens.

    And yes, the GFCI protection doesnt affect or afford protection to the secondary side of the LV transformer.

    If the original lights are installed and maintained correctly, there wont be much benefit in swapping to 12V lights. It's not like it's against current code to have 120V lights in a pool...
    Electricians do it until it Hertz!

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