# voltage question

Discussion in 'Electrical Forum discussion & Blog' started by djcd34, Jul 15, 2009.

1. ### djcd34Junior Member

Joined:
Jul 14, 2009
Occupation:
Pool maintenance & construction
Location:
Boston
I have a pool light I'm replacing and it's 12 volt. The only compatable light that fits in the niche is 120 volt. Can someone tell me what the difference between them actually means? The wattage for both lights is 300. Will The 120 volt work/ What does low voltage actually mean?

Joined:
Oct 7, 2005
Location:
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The 12 Volt system is most likely direct current, the 120 Volt bulb is designed for AC. It will not work in your 12 Volt system. I suggest you go to a place which sell pool supplies (?) or an electical supply house and bring the old one with you.

4. ### ThatguyHomeowner

Joined:
Aug 27, 2008
Occupation:
A bounty hunter like in "Raising Arizona"
Location:
MD
12v is much safer than 120v, wet skin or dry.
Make absolutely certain you do this job right.

5. ### djcd34Junior Member

Joined:
Jul 14, 2009
Occupation:
Pool maintenance & construction
Location:
Boston
Thx for the help> Like I said though, they don't make a 12 volt light for this niche anymore. Discontinued> SOL.

6. ### jimboPlumber

Joined:
Aug 31, 2004
Location:
San Diego
The 120 volt bulb would barely glow dim on 12 volts. Since code now requires 12 volts on new installation, I am surprised you cannot find what you need. Have you tried a larger pool supply outfit, or google??

7. ### jadnashuaRetired Defense Industry Engineer xxx

Joined:
Sep 2, 2004
Occupation:
Retired Systems engineer for defense industry.
Location:
New England
Think of voltage as the pressure like in water pressure. To get 300W of light out of a 12v circuit, you need a fire hose. Amperage is like the volume. 300/12= 25A. At 120volts, and 300W, you'd only have 300/120=2.5A, or 10x less volume (and you could use smaller wires). Both would use 300W, but one would be doing it by high volume, and the other with high presssure. Because you can't push 25A through the 120vac lamp (you'd get only about 1/10th, not exactly since the resistance changes with temperature), while it probably would light, it might only barely glow and you'd not get anywhere near the illumination out of it.

If they no longer make those bulbs, you'll have to change the fixture. Have you looked on-line or at a well stocked electrical supply store? It's not likely to be something you can find at someplace like HD or Lowes.

8. ### ThatguyHomeowner

Joined:
Aug 27, 2008
Occupation:
A bounty hunter like in "Raising Arizona"
Location:
MD
9. ### hjModerator & Master PlumberStaff Member

Joined:
Aug 31, 2004
Occupation:
Plumber
Location:
Cave Creek, Arizona
bulb

Unless it is powered with a battery, the 12 volt bulb IS AC from a transformer. But since you do not have 120 volt wiring, and you cannot convert the 12 volt system to 120 volt, the 120 volt bulbs will glow like a firefly using 12 volt power.

10. ### Speedy PeteyLicensed Electrical Contractor

Joined:
Jun 16, 2007
Occupation:
Location:
NY State, USA
Not according to the NEC or my local codes. Is this a local amendment for you?

11. ### Speedy PeteyLicensed Electrical Contractor

Joined:
Jun 16, 2007
Occupation:
Location:
NY State, USA
How do we know this for sure? What if the wiring to the deck box is THHN/THWN?
The new wet niche light will come with a new rubber cord, so there is a very real chance the old transformer enclosure can be changed to a splice box or new deck box.

12. ### jimboPlumber

Joined:
Aug 31, 2004
Location:
San Diego

It is what I see people using, and I assumed it was a building code ( not electric code ) requirement. Sort of like they require lights in the bathroom and kitchen to be primarily fluorescent. That is not an electric code, but a building code.

But on the pool lights, I can't quote you chapter and verse, so it could just be a wild ass guess on my part!

13. ### Speedy PeteyLicensed Electrical Contractor

Joined:
Jun 16, 2007
Occupation:
Location:
NY State, USA
Now THAT'S a local California thing. I hope it stays there too!

14. ### jimboPlumber

Joined:
Aug 31, 2004
Location:
San Diego
We don't always love this stuff, but CA has been big on the energy thing. As of a year ago in CA....you cannot buy a 60 watt regular old bulb. Only 57 watt is allowed. 75=51, etc.

But hang on to your wiggins, because these laws invariably go national. A lot of this stems from the EPACT ( Federal Energy Policy Act of 2005). CA is an early adopter of specs, but most of this stuff has started to phase in nationally.

We could move somewhere, and I plan to as soon as I find somewhere that doesn't have floods, tornados, hurricanes, snow, etc! And has a year round temperature such that air conditioning and heating are "nice to have" but not necessary!!!

15. ### hjModerator & Master PlumberStaff Member

Joined:
Aug 31, 2004
Occupation:
Plumber
Location:
Cave Creek, Arizona
wiringt

They COULD have it wired with conduit and THHN, but given that it was probably a Malibu type system, the odds against that being the case are almost astronomical.