Cord & plug pool pump, bond & ground question

[mark32]

An old timer came into HD today and had some #8 solid cut for himself, then asked me for an FS box w/two entry's so he could run run his bond into it. I asked him why and his plan was to install his twist lock, for the pool pump, in the box then wire nut the equipment ground to the #8. Inside I started laughing but we began discussing the code which he seemed knowledgeable but I had to admit to him that it is not the intend of the code for him to do that and also, his idea was one I've never heard of or saw. His thinking is that if one were to unplug the pump, there would no longer be an equipment ground and bond connection at the pump. After he left it dawned on me that he maybe onto something. It is possible that if the pump were unplugged, there could be a difference in potential between the pump housing and the metal box the twist lock is mounted in. Does this makes sense?

 

[ericsherman37]

I'm not sure if I follow. So the #8 solid is a bonding jumper from the pump housing, running into the box, independent of the cord and plug cable, and tied into the equipment ground from the branch circuit? And so the pump could be unplugged but the bond to the box would still be intact?

That's weird but if they were solidly connected by the #8 even when the pump is unplugged I don't see how there could be a significant difference of potential unless it's like a zillion feet away. NEC 680.7 covers pool-related cord-and-plug equipment in general, and 680.21(A)(5) covers permanently installed pools (which I assume is the situation). Neither allow pool pump motors to have a cord longer than 3 feet, and it must contain an EGC. If he bonds everything together per the code then he shouldn't need an independent bonding jumper for his pump. The branch circuit EGC should be adequate, and if he has a metal box for the plug, it should be bonded to the EGC also.

Am I reading your post correctly? It was slightly confusing to me

 

[ericsherman37]

...his plan was to install his twist lock, for the pool pump, in the box then wire nut the equipment ground to the #8.

That EGC needs to be bonded to the metal box as well as wired into the receptacle.

 

[mark32]

Hey Eric, thanks for the response. I kinda rushed the post as I was running out for dinner at the time. You interpreted my post well.

Your line "The branch circuit EGC should be adequate, and if he has a metal box for the plug, it should be bonded to the EGC also." I assume he was going to bond the box as well but the #8 isn't there to supplement the egc, only to maintain a bond between the pump housing, and all that's bonded to it, and the receptacle box when pump is unplugged. I agree it's strange but he said his inspector has never said anything to him about it in the past and he's very particular, according to him.

 

[infinity]

Did he say what kind of pool this was? Storable pools don't even need to have their metal parts bonded.

 

[M. D.]

If the pump were of the double insulating type ,..
2008 NEC 680.26(6)
" Where there is no connection between the swimming pool bonding grid and the equipment grounding system for the premises , this bonding conductor shall be connected to the equipment grounding conductor of the motor circuit."

 

[ericsherman37]

...the #8 isn't there to supplement the egc, only to maintain a bond between the pump housing, and all that's bonded to it, and the receptacle box when pump is unplugged...

If the pump is unplugged then it doesn't need to be bonded to anything until it's plugged back in - there isn't going to be any danger of non-current carrying parts being energized. That's what the EGC in the plug is for. But as long as his branch circuit EGC is bonded to the pump housing when it's plugged in that's all he needs. If he wants to run extra #8 bonding jumpers all over the place I don't see why it would hurt anything. It's his money :grin:

 

[mark32]

Hello again Eric, what you've typed is exactly what I told the gentleman, that being: "If the pump is unplugged then it doesn't need to be bonded to anything until it's plugged back in - there isn't going to be any danger of non-current carrying parts being energized". Thanks