Why #8 EGC for wet-niche pool light

[hotlegs]

680.23(B)(2)(b) Wet-Niche luminaires ,"Where a nonmetallic conduit is used, an #8 AWG copper EGC shall be installed in this conduit unless a listed low-voltage lighting system is used . The EGC shall be terminated in the forming shell, J-box or XFMR enclosure." Its my understanding that if you have a nonmetallic conduit you would run a #8 EGC from the forming shell to the J-box that is set 4' from the pool to supply power to the pool lights. At the J-box if you have a 120V circuit with a #12 EGC supplying power to the light why then the need for the #8 EGC if all you have going back to the panel is a #12 EGC? Does it have something to do with corrosion? Thanks.

[ September 20, 2004, 10:58 PM: Message edited by: hotlegs ]

 

[heco]

Re: Why #8 EGC for wet-niche pool light

Low resistance and crossion resistance....a stranded conductor of #12 would deterioate with any [ and there will be] water especially with large doses of chlorine [during shock treatent]..

# 8 solid will withstand the enviorment and carry fault current easier....

I think??????

 

[heco]

Re: Why #8 EGC for wet-niche pool light

here it is from the Handbook..

Where rigid nonmetallic conduit or liquidtight flexible nonmetallic conduit is used between a forming shell for a wet-niche fixture and a junction box or other enclosure, an 8 AWG insulated copper equipment grounding conductor is required to be installed in the conduit to provide electrical continuity between the forming shell and the junction box or other enclosure. The conduit must be sized large enough to enclose both the 8 AWG insulated copper bonding conductor and the approved flexible cord that supplies the wet-niche fixture, to facilitate easy withdrawal and insertion of the grounding conductor and the cord. Low-voltage lighting systems are exempt from this equipment gounding conductor requirement.

 

[rick5280]

Re: Why #8 EGC for wet-niche pool light

You seem to be forgetting the other part of this, which is the bond wire connecting the forming shell to the bond grid. This connection is made on the outside of the shell, and the wire is run to and connected to the bond grid which is required to be installed.

If you follow this connection, it goes from the grid to the forming shell, up to the junction box, where it is connected to the junction box and any incoming equipment ground wires in the junction box.

This connection, of the grid to the equipment ground wire of the light, eliminates any potential difference that may exist if the connection were not there.

Lay on the deck with hands in water, removing the light for lamp replacement, and you can see the need for all this equipment to be onded together.

The #8 in the conduit feeding the forming shell is not for fault clearing. That is the function of the neutral and equipment grounding conductor within the light supply cord.

Rick Miell

[ September 22, 2004, 12:10 AM: Message edited by: rick5280 ]