NEC 250.22(5)
NEC 250.22(5)
(OP)
Does anyone know why NEC 250.22(5) specifically says not to ground the secondary circuit of a pool lighting system?
I know that the NEC allows circuits to be ungrounded if interrupting the operation of the circuit would be less harmful than an uplanned interruption of the circuit. This makes sense to me in the case of heavy industrial operations that cannot suddenly be stopped, but I can't understand why the same rules would apply to swimming pool lighting.
I know that the NEC allows circuits to be ungrounded if interrupting the operation of the circuit would be less harmful than an uplanned interruption of the circuit. This makes sense to me in the case of heavy industrial operations that cannot suddenly be stopped, but I can't understand why the same rules would apply to swimming pool lighting.






RE: NEC 250.22(5)
RE: NEC 250.22(5)
It makes sense to me, but the answer is very long and complex. I suggest you look into the UL standards for underwater lighting, the prohibition arises there. They're designed to absolutely eliminate the potential for contact with the water, which is also a mighty good ground in lots of cases. It's a ground that is remote from the electrical system ground, which can cause troubles during lightning or large fault events.
Maybe someone else has more time to give you a more complete answer...
Good on ya,
Goober Dave
RE: NEC 250.22(5)
Essentially, it is to limit how much current can flow to ground. If you do not have a direct return path, IE a ground connection, minimal current will flow (the amount that will is due to capacitive coupling). IE if your supply line faulted and went to ground, it will try and return to its source through any and all possible paths. So if you eliminate the path of return and maximize the resistance, minimum current will flow. I=V/R.
There might be additional thoughts into this, but I believe this is the essential thoughts behind this.
RE: NEC 250.22(5)