PDA

View Full Version : Secondary side of transformer gfci


RLI Electric
03-26-2010, 05:25 PM
Is there a product that allows secondary side of the transformer to be gfci protected? I am looking for a way to be able to get closer than 10 feet from the edge of a swimming pool with light fixtures. Due to NEC 411.4 (B) we have to be 10 feet away. If we have a gfci protection for the secondary side, then we can be within 5 feet per article 680. Actually if there was a device, I wonder if this would have solved James' electrified cooler on his yacht:)

irrig8r
03-27-2010, 09:36 AM
Have you thought about using fiber optics?

http://www.illuminfx.com/

David Gretzmier
03-27-2010, 10:31 AM
I am certain everyone on here would never think of putting a path or tulip light closer than 10 foot from the edge of a pool, ( "HEY GEORGE ! GET THE TAPE ! WE NAY BE VIOLATING CODE OVER HERE BY THE SLIDE!") Much like I am sure none of us non electricians have ever done remote photo-cells on the primary side by cutting into and running 120v and wiring it up beyond the trans to get to a dark spot. or wiring in longer 120v cords on trans.

JoeyD
03-29-2010, 12:59 PM
Inspectors across the US are enforcing NEC Article 680 on a regular and consistant basis. Sure if your putting in an area light or bullet light its easier to try and get away with it knowing the worst case scenario is having to pull the fixture up and relocate it. But if you decide to embed step lights into concrete and you are within 10ft the cost of removing and relocating just went up BIG TIME! So we have developed a fiber optic system that allows you to run fixtures within 5ft of the waters edge without any fear of code viotaltion and we did this with low voltage powered Fiber Optics. With the Unique Intelli Fiber Optic System you simply locate your 24v Illuminator 10ft or beyond the outer edge of your pool and spa. We then have a selection of fixtures for you to choose from that will accept the fiber optic cables! I could go on but check out our site and watch our videos and let me know if you have any questions!

http://www.uniquelighting.com/product_pages/intelli_fiberoptics.htm

http://www.youtube.com/watch?v=7bN_0XhAmSs

http://www.youtube.com/watch?v=huydgIZ91l8

http://www.youtube.com/watch?v=NQK9CwBL1l4

David Gretzmier
03-30-2010, 12:05 AM
Joey- neat system. I like the options on 25 or 50 strands. sounds very high tech. On the 700 hour life of the fiber optic source bulb, do you reccomend selling the customer on a bimonthly or quarterly bulb replacement on that? I am thinking that on "dusk to dawn" folks at 12 hours a night, 60 days is gonna come up fast. even at 6 hours a night your looking at 4 months tops. is there not a long life 250 watt bulb out there? nice videos, by the way.

steveparrott
04-01-2010, 08:47 AM
Bob, are you sure that secondary GFCI protection allows you to install within 5 ft. of water? I've been told in the past that this is not the case.

RLI Electric
04-01-2010, 09:08 AM
Take a look at this picture from the 2005 NEC. I spoke with a building official who is on the mark with NEC. Looking at this diagram you would instinctively say within 5 feet is ok because the transformer is gfci protected. The problem is that the gfci only protects the primary side of the transformer. The secondary side can have a ground fault and go unnoticed by the gfci, hopefully the picture is blown up enough.

INTEGRA Bespoke Lighting
04-01-2010, 09:33 AM
Can you explain to me how the secondary side of a 12Vac transformer could have a ground fault when there is no grounding circuit that runs from the secondary side circuit to the fixtures etc.

Of course you are using a Pool & Spa rated transformer, right?

RLI Electric
04-01-2010, 09:41 AM
What if it shorts to a person and completes its path to ground? Gfci may not see it and the breaker in the transformer may not trip. Splitting hairs here but that is what the fun of the NEC is. You think you have it good one way (the chart) and then there is a zinger waiting from you another way (an inspector who says "what if") Low voltage wires have some pretty high currents. Pool spa rated xfmr, naturally:)

emby
04-01-2010, 11:27 AM
What if it shorts to a person and completes its path to ground? Gfci may not see it and the breaker in the transformer may not trip. Splitting hairs here but that is what the fun of the NEC is. You think you have it good one way (the chart) and then there is a zinger waiting from you another way (an inspector who says "what if") Low voltage wires have some pretty high currents. Pool spa rated xfmr, naturally:)

Dug this up for you. Did a search on low voltage and ampacity hurting a person.
Personally I would like to debate the rules around pools when installing low voltage fixtures. IMOP if you were to be standing in a swimming pool and leaned to touch the terminals on a low voltage light bulb I bet I will still be around to talk about it. Please see below.

I've got a multimeter in front of me, so I'll measure the resistance between my hands. It reads about 1MOhm or 1 million ohms. It varies significantly depending on how hard I squeeze the probes and how moist my fingers are etc. If I was to put my hands on the terminals of a 12 volt car battery, the current flowing through my body would be about 12 microamps, not much. If I was to put my hands on the terminals of a 12 volt lantern battery, the current would still be about 12 microamps. The current is the same because the resistance of my hands is millions of times greater than the internal resistance of the batteries. It doesn't matter that the car battery can deliver 500 amps, my hands will only pull 12 microamps out of the battery.

So what's the answer? Is it the volts or the amps? Basically, it's both. Low voltage (less than 50 volts) won't hurt you because of high skin resistance. High voltage can cause a heart attack if the source can deliver moderate current (100 milliamps). High voltage coupled with the availability of high current (like power lines) can result in lethal shock as well as serious burns and tissue damage. Electricity is an inanimate beast without compassion or remorse. It must be respected at all times.

RLI Electric
04-01-2010, 06:30 PM
The code can be frustrating but we have to remember it is a minimum. It has to protect the possibility rather than the inevitability. I agree that chances are you would still be around but there can be that one frail grandma that in the middle of a game of Marco Polo reaches out and grabs a light to help her butt out of the water. Bang, she gets it. 12 searing volts of pure hellacious agony. The whole family watches wide-eyed with terror as she burns like a light bulb. Kids cry, women weep and men get sick. The neighors lights dim and they look outdoors only to see the scene unfolding before their distraught eyes. Wow, maybe a little too much coffee this afternoon.

irrig8r
04-01-2010, 09:12 PM
The code can be frustrating but we have to remember it is a minimum. It has to protect the possibility rather than the inevitability. I agree that chances are you would still be around but there can be that one frail grandma that in the middle of a game of Marco Polo reaches out and grabs a light to help her butt out of the water. Bang, she gets it. 12 searing volts of pure hellacious agony. The whole family watches wide-eyed with terror as she burns like a light bulb. Kids cry, women weep and men get sick. The neighors lights dim and they look outdoors only to see the scene unfolding before their distraught eyes. Wow, maybe a little too much coffee this afternoon.

Whoa... that's some strong coffee...

Tim R.
04-02-2010, 09:19 AM
The code can be frustrating but we have to remember it is a minimum. It has to protect the possibility rather than the inevitability. I agree that chances are you would still be around but there can be that one frail grandma that in the middle of a game of Marco Polo reaches out and grabs a light to help her butt out of the water. Bang, she gets it. 12 searing volts of pure hellacious agony. The whole family watches wide-eyed with terror as she burns like a light bulb. Kids cry, women weep and men get sick. The neighors lights dim and they look outdoors only to see the scene unfolding before their distraught eyes. Wow, maybe a little too much coffee this afternoon.

:laugh::laugh::laugh:

emby
04-04-2010, 12:35 AM
Been busy this weekend so I am catching up on the posts.
Bob, I gotta tell you..I read your response this morning and I went out to get coffee this afternoon and started to giggle again. That was freakin funny!!!!:laugh: