Swimming pool - stray voltage?

[W1RKW]

This is somewhat off topic but it is electrical in nature.

I'm trying to help a friend who lives across country trouble shoot through email a problem which sounds like he has a stray voltage problem on his swimming pool. 

He gets a mild tingle when exiting the pool via a metal ladder that's partially submerged in the water and when he's partially submerged in the water. In other words his feet are in the water and his hands are above the water gripping the metal ladder.

He tells me he has an 8ft. ground rod and is directly attached to the pump motor with a number 6 wire. The motor and ground rod are about 6 ft apart.

The power feed is about 150ft (direct burial #12) to the main panel in the home which connects to an outside  panel that has 2 circuit breakers out at the pool end. One CB is for the pump the other is for the pool heater.

He tells me the ground wire from the feed is not connected and the pump motor has been replaced because the original one did the same thing.

I've told him to disconnect the wiring from the heater in an effort to isolate the two circuits.  Beyond that I don't know how else to trouble shoot this.  Any ideas?

[KB2WIG]

GACK !!    It sounds like your friend is in a good position to kill himself.  I would tell him to find an electrician that works for a pool co. and have the pool checked by a profesional......  But, he probably is cheep (like me).... ..

Some thoughts... 

The next door neighbors 'lectrical sys may be having a problem and is looking for a ground through the pool. Believe it or not.

An electrician who works in the agricultural field may be helpful. Cows in a dairy dont like stray voltage, and it effects the milk production. Believe it or not.

ANYWAY, follow this link....


http://www.egr.msu.edu/age/aenewsletter/1_may_june_06/truman5_06.htm

[WA3VJB]

Is there an underwater light in that pool ?
Housing intact?

But your suggestion is good to completely lift the circuit to the heater AND the pump. In fact, I would lift the supply to that sub-panel at the MAIN BREAKER BOX end, rather than at the pump/heater, to eliminate the possibility there's anything between ground and neutral coming from some other source in the house (or the neighbors !!!)

By lift, I mean to throw OFF the main breaker from the street, and unscrew the bus to the breaker(s) that serve the sub-panel, and lift the hot, neutral and ground wires. Completely isolate the circuit.

Especially on long runs like that, it's possible to get a perceptible voltage differential.

Which reminds  me -- does he have some other way to "test" than to climb in the pool and have a feel ? 

If that feed to the sub-panel is 120 (not 240), perhaps one of those line detectors could determine if someone has swapped ground and neutral. These usually plug in the wall, but with some care you can get them across the line to validate hot-neutral-ground.

Another thought -- is he anywhere near a broadcast station? Could be RF.

or maybe BPL !!!

[Carl WA1KPD]

This is fun to read about as we finish up the construction of our pool. Hope we have a good electrician!

Beware Swimming Pool Shock Attacks
Feds Warn Of Poolside Hazards As Summer Season Nears

   
WASHINGTON, May 20, 2003
 (CBS/AP)

   
(AP) With Memorial Day approaching, federal safety officials warned Tuesday of hidden hazards that lurk near a summertime hot spot — the swimming pool.

The Consumer Product Safety Commission urged people to be aware of the risk of electrocution at backyard, community and public pools. The alert also applies to hot tubs and spas.

According to CPSC, electrical hazards in and around swimming pools have resulted in 60 deaths and nearly 50 serious shocks in the past 13 years.

Among the greatest concerns: faulty underwater lighting, aging electrical wiring, and sump pumps and vacuums that are not grounded. Radios, TVs and dangling extension cords also pose a danger.

CPSC joined with the American Red Cross to kick off the “Don't Swim With Shocks” campaign.

CPSC Chairman Hal Stratton advised consumers that the “best protection for families is inspection, detection and correction.”

One step they can take is to make sure lighting, circuits and other possible hazards are protected by Ground-Fault Circuit-Interrupter outlets, or GFCIs. These safety devices monitor a circuit's electrical flow, and if any problems are detected they automatically shut off power to that circuit.

CPSC asked pool owners to familiarize themselves with all the electrical switches and circuit breakers for pool equipment and lights, and to know how to turn off those switches in an emergency. Other tips included using battery-operated appliances instead of cord-connected equipment.

In the event of shock or electrocution, the Red Cross recommends turning off all power and using a fiberglass hook — a nonconductive device — to rescue the victim.

[WA1GFZ]

building inspector made us bond all the metal vertical supports to the ground return with a #8 bare when we did my Dad's pool. The voltage offset could be coming from anywhere even a neighbor. Bond it all to a common ground wire back to the service ground. I think we brought my Dad's back to the panel. after once around the pool and the case of the pump.

[wa1knx]

what you think of as ground, the neutral wire often times is not
at "ground" potential.  I had the same thing at my berlin ma
place. I could touch the cold water faucet, the ground rod to
the electical system etc, and get a shock.  the neutral wire was
coming in with 14vac above the real ground.  I had the power
company out and showed them. they did not know how to fix.
tying all the pool equipment, the railings etc to the common
electrical ground would be the best start. a series of ground
rods all around the pool tied in also might "raise" the potential
of the immeditate ground to that of the neutral. thats assuming
this problem is of the same nature.

[WB3LEQ]

Electric and water never mix.  Here is a link to another website to a similar situation but this was a pond where this took place:
http://forums.mountaineeroffroad.com/viewtopic.php?t=5397
Your friend needs to stay out of that pool and small children could suffer lethal consequences.

[Blaine N1GTU]

shouldnt all those breakers be GFI?
electrifying!!! SHOCKING!!!

[W1RKW]

I'm still waiting for a response from my friend.  I should have something by this afternoon and some results.

One thing I did not ask until now was whether this shock he was getting occurred when the pump was on or off.  So I'm waiting on that answer.  That should have been the first question.

One thing I did not mention in my previous post was the voltage he measured between the pool ladder and the water was around 10V.

[KF1Z]

Eek.....

A pool pump, and heater.... on 150 feet of #12?

I wonder if it's 240v, AND if the wire is at least 3 wire WITH ground....  (12/3 w/g)

If that's a 240 volt circuit, running on a 12/2, there may be a good source of a problem.

Wonder why the ground wire from the feed isn't connected??



I have to agree with whoever said it earlier.....

If it isn't easy to troubleshoot for him.... then his best bet is to get an electrician who is familiar with the local codes having to do with swimming pools to fix it......

I know... doesn't want to 'cause he wants to do it himself.... and not pay someone else to do it..... but gee whiz......

[WA1GFZ]

it is a no brainer fix just bond everything to a common ground.

[flintstone mop]

GFI's may suck, and trip for the dummest reasons, but it is a necessity.
Definitely sounds like "electrical leakage current" (pun intended) problem.
Fred

[W5AMI]

Bottom line here, as someone else suggested; get a GOOD Master electrician out there to lurk around and figure out the problem.  Get documents from him with time and date of when he made his analysis, and hopefully a fix.

Don't' take any chances with this situation from amateurs!  There are a lot of good ideas here, but get someone (qualified) out there to look.  A few spent dollars is well spent to protect the lives of those who venture into your pool.

Brian / WA5AM

[W1RKW]

Turns out the voltage he was seeing at the ladder would only appear when the pump was running.  There was no potential when the CB was open.  I told him to connect all his grounds in the outside CB panel. 

Problem solved. Thanks for the input

[k4kyv]

what you think of as ground, the neutral wire often times is not
at "ground" potential. 

You should NEVER think of the neutral as "ground".  The neutral should be treated exactly the same as a hot wire.  The ground should be a separate wire altogether.  There should be one and only one connection between ground and neutral, and that should be right at the service entrance to the building.

My shack is about 75 ft. from the house.  I notice enough potential difference  between ground and neutral in the shack to make a spark if the two are shorted together. I also noticed that if I temporarily ground the neutral wire in the shack, I get a.c. hum in about every piece of audio equipment in the station as a result of the ground loop.

The electrical code says I could ground the neutral where the electrical wires come into the shack and treat it as a second service entrance, but because of the ground loop problem I keep them separated, so that the only place on my entire property where the neutral wire is connected to ground is at the main service entrance to the house.

The BC1-T broadcast transmitter runs off 240 volts, and they ground the neutral directly to the transmitter cabinet.  I don't know why the did it that way, since it is a violation of the electrical code.  One of the first things I did to mine when I got it running was to lift the neutral wire from the cabinet, and run a separate heavy conductor from the cabinet to earth ground.

[W3TDH]

  I know that you believe that your friends problem is solved but it is not!  He has a direct buried underground feeder supplying a panel that serves pool equipment.  This renders the Equipment Grounding Conductor (EGC) vulnerable to corrosion.  All wiring outside the home that is used to supply pool equipment must contain an insulated EGC in order to maximize it's resistance to the corrosive effects of pool chemicals.  All of the grounding or bonding connections that are exposed to the air or to splashes of pool water should be potted with a water proof anti corrosion compound.  All of the EGCs must be connected all the way back to the service equipment's main bonding jumper.  If any of these things are not corrected it is only a matter of time before his stray current problem will return. 
--
Tom Horne, W3TDH

"This alternating current stuff is just a fad.  It is much too dangerous for general use."  Thomas Alva Edison

[W1RKW]

Tom,
Thanks for the input but one step ahead of you.  I recommended the exact same thing that you recommended.  Whether he has done this or not, or will he do it or not, I will not have proof. He could tell me one thing and it be another.  I can only hope.

[WA1GFZ]

yup in Ct. we had to run a #8 solid wire around the pool back to the panel bonded to the pool at the vertical supports.

[W3TDH]

Tom,
Thanks for the input but one step ahead of you.  I recommended the exact same thing that you recommended.  Whether he has done this or not, or will he do it or not, I will not have proof. He could tell me one thing and it be another.  I can only hope.

In addition to being a working electrician I'm also a volunteer fire fighter / rescuer.  In my work on the ambulance I've seen several electric shock victims.  Three were electrocutions.  Several persons have drowned along the Chesapeake bay as a result of being paralyzed  by stray current flowing through water in which they were swimming. 
--
Tom Horne, W3TDH