Swimming Pool Electrocutions

[FionaZuppa]

Isn't that where step potential rears its ugly head?

run a salt water pool

 

[goldstar]

I may be wrong

But I think the rebar in poured concrete pool wall has been required to be grounded, for a long time (since 1962?)

And the 3' walkway much more recent (2005?)

http://www.neetrac.gatech.edu/publications/Jodie_Lane_2007.pdf

OK, fair enough. I'll buy that.

 

[FionaZuppa]

I may be wrong

But I think the rebar in poured concrete pool wall has been required to be grounded, for a long time (since 1962?)

And the 3' walkway much more recent (2005?)

http://www.neetrac.gatech.edu/publications/Jodie_Lane_2007.pdf

"grounded per 250"
so basically, bond the rebar to pump which gets you bonded and grounded (thus you can stop here), but perhaps add some ground rods around the pool, bond rebar to rods (recommended).

NFPA 70 section 250 makes reference to lightning protection in the bonded/grounded system, and then ref's NFPA 780-2014

 

[kwired]

"grounded per 250"
so basically, bond the rebar to pump which gets you bonded and grounded (thus you can stop here), but perhaps add some ground rods around the pool, bond rebar to rods (recommended).

NFPA 70 section 250 makes reference to lightning protection in the bonded/grounded system, and then ref's NFPA 780-2014

To satisify 250 all one needs is an EGC run to the motor, and grounding electrode system if dealing with a service or feeder to separate structure.

All the additional bonding required for swimming pools comes from art 680. The primary function of such bonding is not fault clearing or lightning mitigation, it is there to equalize potential so users don't come into contact with objects that are at different potential. Driving ground rods around a pool could actually make shock hazard worse instead of better for users of the pool.

 

[FionaZuppa]

kwired, did you read the pdf?

it is 680, making ref to 250, and in 250 it makes ref to other things like lightening protection.

 

[kwired]

kwired, did you read the pdf?

it is 680, making ref to 250, and in 250 it makes ref to other things like lightening protection.

Note that the only parts that reference 250 are from 1962 and 1975 NEC. 1984 it states:

"1984 NEC – A very significant change / clarificationadded a fine print note mentioning the purpose of
bonding is to eliminate voltage gradients in the pool."

Art 250 still must be complied with for equipment grounding purposes, but all that additional bonding required at swimming pools that isn't required most anywhere else is to protect the users from voltage gradients. If you have an older pool that did not require such bonding when it was constructed, you have a potential liability on your hands. POCO could have troubles a couple miles down the road and cause a shock hazard in your pool if it doesn't have equipotential bonding that has been required for some time now.

 

[Danelectron]

taking-the-mystery-out-of-equipotential-bonding-requirements-for-swimming-pools


Some good info.

 

[FionaZuppa]

taking-the-mystery-out-of-equipotential-bonding-requirements-for-swimming-pools


Some good info.

it says the below, i added in the red. 680 is nothing more than extending the egc to the elements defined in 680.

Bonding requirements are an important and unique protective method employed to increase the safety of the users of bodies of water such as pools, spas, and hot tubs. Bonding connects the conductive elements of the pool structure, nearby metallic objects, and electrical equipment enclosures together, essentially grounding everything, in essence is an extension of the branch ckt EGC to everything metal in & around the pool/spa.

 

[kwired]

it says the below, i added in the red. 680 is nothing more than extending the egc to the elements defined in 680.

EGC is effectively extended to those items, but has nothing to do with the intent of bonding all those items together.

The bonding jumper(s) must also be no smaller then 8 AWG regardless of what size EGC is required. A pool could have only a single 12 AWG EGC run to a pump motor as the only connection to the electrical panel, still need 8 AWG bonding jumper from that motor to the rest of the equipotential bonding system.

If the motor develops a ground fault and for some reason the EGC has failed, proper equipotential bonding simply raises the voltage of the entire pool vicinity over remote earth, users won't know anything about the faulted pump. Same situation but with a pool with "holes" in the equipotential bonding may see someone get electrocuted when they grab hold of say a non bonded ladder or some other similar situation.

 

[FionaZuppa]

EGC is effectively extended to those items, but has nothing to do with the intent of bonding all those items together.

The bonding jumper(s) must also be no smaller then 8 AWG regardless of what size EGC is required. A pool could have only a single 12 AWG EGC run to a pump motor as the only connection to the electrical panel, still need 8 AWG bonding jumper from that motor to the rest of the equipotential bonding system.

If the motor develops a ground fault and for some reason the EGC has failed, proper equipotential bonding simply raises the voltage of the entire pool vicinity over remote earth, users won't know anything about the faulted pump. Same situation but with a pool with "holes" in the equipotential bonding may see someone get electrocuted when they grab hold of say a non bonded ladder or some other similar situation.

sure yes, you describe what it means to extend EGC to all of the items described in 680, with 680 rules for "bonding". ..... and ?

 

[kwired]

sure yes, you describe what it means to extend EGC to all of the items described in 680, with 680 rules for "bonding". ..... and ?

Apparently you are not understanding the already mentioned in readydave8's attachment:

"1984 NEC – A very significant change / clarificationadded a fine print note mentioning the purpose ofbonding is to eliminate voltage gradients in the pool."

Extending the EGC to everything else in the pool is just a side effect of doing this, not the intention of why the bonding is mandated.

 

[FionaZuppa]

Extending the EGC to everything else in the pool is just a side effect of doing this, not the intention of why the bonding is mandated.

yep.