Getting Shocked In Spa

[Zapped]

Hi,

I have searched and haven't found much information on this subject.

We are disappointed to still be having a problem getting shocked in our new inflatable spa. We had an indoor, inground pool that is currently a renovation project that also had this problem. We had lots of electricians/pool/ power company people out and they could never resolve the issue. We are the only house at the end of a 1.5 mile drive and have problems with surges and scavenger electricity.

The shocking occurs sporadically. For instance it was too strong to tolerate last night (felt like getting lemon juice in a cut) but was fine this morning. It happens with the gfi off but when the motor/filter/heater plugged into the outlet. Unplugged there is no shock. It happens when skin contacts the water in the spa while standing outside the spa. The spa is on a concrete floor in the same room as our indoor pool. I didn't test it to see what happened if I was standing on any kind of insulator. Also, it was first noticed after adding the hardener and pH up(using baquacil/softswim), could we be creating a battery type problem? We live next to a creek and all the ground water here is fairly acid (5.5+-).

What do you think? Could this be a bonding issue? We have a wood framed iron support beam in the wall behind the spa, probably 10" away. Our house is notorious for being poorly built, could there be a problem originating from the pool?

Could it be a grounding issue? Because of the scavenger electricity and surge problems, the electricians have installed lots of copper grounding rods. Could we have too many?

Thank you for any thoughts.

Zapped

[n1oty]

Hi,

I have searched and haven't found much information on this subject.

We are disappointed to still be having a problem getting shocked in our new inflatable spa. We had an indoor, inground pool that is currently a renovation project that also had this problem. We had lots of electricians/pool/ power company people out and they could never resolve the issue. We are the only house at the end of a 1.5 mile drive and have problems with surges and scavenger electricity.

The shocking occurs sporadically. For instance it was too strong to tolerate last night (felt like getting lemon juice in a cut) but was fine this morning. It happens with the gfi off but when the motor/filter/heater plugged into the outlet. Unplugged there is no shock. It happens when skin contacts the water in the spa while standing outside the spa. The spa is on a concrete floor in the same room as our indoor pool. I didn't test it to see what happened if I was standing on any kind of insulator. Also, it was first noticed after adding the hardener and pH up(using baquacil/softswim), could we be creating a battery type problem? We live next to a creek and all the ground water here is fairly acid (5.5+-).

What do you think? Could this be a bonding issue? We have a wood framed iron support beam in the wall behind the spa, probably 10" away. Our house is notorious for being poorly built, could there be a problem originating from the pool?

Could it be a grounding issue? Because of the scavenger electricity and surge problems, the electricians have installed lots of copper grounding rods. Could we have too many?

Thank you for any thoughts.

Zapped

The multiple ground rods can contribute to the problem, unless they are also directly tied together. You must BOND all metal together in an equipotential bonding grid. From your description, it sounds like the problem is external to the tub, however, it would be prudent to test all tub loads with a high quality megohmmeter.

John

[quantumchromodynamics]

If you can feel that much electricity, then your tub is not safe to use. You need to have your entire electrical system checked by an electrician. Stray current is often caused by inadequate or overloaded neutrals that are grounded. Have the electrician check the neutral to ground voltage and current.

Ohm's law equation (formula): V = I × R

Power law equation (formula): P = I × V.

P = Power in watts.

I = Current in amps

V = voltage in volts

R = resistance in Ohms

For example: A 1.5 H.P pump connected to your 115-volt line. Voltage from neutral to ground with no load should be 0 volts. When the pump is turned on the voltage from neutral to ground could go to 4 volts and the voltage at the pump could go to 111 volts. The current draw would be about 9.73 amps. Since the neutral is connected to ground, any potential difference (voltage) will cause current to flow from neutral into the ground.

Power being used for the pump was 111 volts x 9.73 amps = 1080 watts (1.45 horsepower)

Total Resistance was 11.4 ohms

At 4 volts and 9.73 amps, the power lost to the ground is 38.92 watts. This is one source of the stray voltage that pool owners sometime report being able to feel when they touch their water.

This means that the neutral has a resistance of 0.4111 ohms. This would correspond to a 100-foot 16-gauge wire. This is an example of an overloaded circuit. The correct wire for this neutral would be 10 AWG Copper, which would have a resistance of only .11417 Ohms.

If the resistance of the neutral was only 0.1 ohms, then the voltage from neutral to ground would have only been 0.973 volts, the power loss would only have been 9.47 watts.

The higher the current being carried by the neutral and/or the higher the resistance of the neutral, the higher the voltage differential from neutral to ground and the higher to power loss to ground.

For example, if a 0.4-ohm neutral is loaded with a total of 30 amps, the voltage from neutral to ground would be 12 volts and the power lost would be 360 watts. This is a loss of ten percent of your voltage and a loss of ten percent of your power.

This demonstrates why it is important to limit the use of the neutral to carry current and to make the wiring as conductive as possible. 230-volt equipment does not use the neutral.

The more the neutral is used, the more inefficient it becomes.

[Dr. Spa]

If you have more than one "grounding rod", you have a serious problem. Just because someone "is" and electrician, doesn't mean they have the experience, qualifications or knowledge to deal with an issue as rare or unusual as this (think OBGYN performing open heart surgery.....hey, he's a doctor, right?).

Some info on "grounding rods"...

Grounding through a grounding rod has its limitations. Grounding (earthing) of electrical equipment doesn't provide a low-impedance fault-current path to clear ground faults (translation: "lower" voltages don't travel well, or freely, through the surface of the earth). In fact, according to the NEC, code prohibits the use of the earth (a grounding rod) as the sole return path because it's a poor conductor of current at voltage levels below 600V [250.4(A)(5) and 250.45((4)]. In reality what this could do is potentially electrify the ground around the spa and has the potential of ELECTROCUTING you. If you were to be standing on the ground and touch something that IS properly grounded you could be fatally electrocuted (electricity in the electrified ground travels up through you and out to what your touching, which is properly grounded). There's actually a documented case of this happen at a fish farm in the UK. The little fishies were periodically being electrocuted from an improperly grounded/bonded power line TWO MILES AWAY.

Have you been there through a rainy season? Did it go away when the ground became water saturated (increasing the grounding ability of the "dirt").

I would tend to go back to the power company and ask them to check out any transformers in the area to see if any have a ground leak or stray voltsge (I seem to recall reading a few articles some time ago about this happening and the result was exactly what you're describing..AND they involved homes at the end of the power line run.)

There's also a weird and DANGEROUS test you can do to prove where the voltage is coming from. Get a volt reading from the water to "dirt"(what you're standing on when you feel the shock). THEN disconnect the ground (ALL grounds) from the spa and retest. If the voltage reading goes away, the electricity is coming from the "DIRT", passing through you and out the spas grounding wire.

[bart6453]

If you have more than one "grounding rod", you have a serious problem. Just because someone "is" and electrician, doesn't mean they have the experience, qualifications or knowledge to deal with an issue as rare or unusual as this (think OBGYN performing open heart surgery.....hey, he's a doctor, right?).

Some info on "grounding rods"...

Grounding through a grounding rod has its limitations. Grounding (earthing) of electrical equipment doesn't provide a low-impedance fault-current path to clear ground faults (translation: "lower" voltages don't travel well, or freely, through the surface of the earth). In fact, according to the NEC, code prohibits the use of the earth (a grounding rod) as the sole return path because it's a poor conductor of current at voltage levels below 600V [250.4(A)(5) and 250.45((4)]. In reality what this could do is potentially electrify the ground around the spa and has the potential of ELECTROCUTING you. If you were to be standing on the ground and touch something that IS properly grounded you could be fatally electrocuted (electricity in the electrified ground travels up through you and out to what your touching, which is properly grounded). There's actually a documented case of this happen at a fish farm in the UK. The little fishies were periodically being electrocuted from an improperly grounded/bonded power line TWO MILES AWAY.

Have you been there through a rainy season? Did it go away when the ground became water saturated (increasing the grounding ability of the "dirt").

I would tend to go back to the power company and ask them to check out any transformers in the area to see if any have a ground leak or stray voltsge (I seem to recall reading a few articles some time ago about this happening and the result was exactly what you're describing..AND they involved homes at the end of the power line run.)

There's also a weird and DANGEROUS test you can do to prove where the voltage is coming from. Get a volt reading from the water to "dirt"(what you're standing on when you feel the shock). THEN disconnect the ground (ALL grounds) from the spa and retest. If the voltage reading goes away, the electricity is coming from the "DIRT", passing through you and out the spas grounding wire.

wow....this is a scary one for sure.....I would hook up my fluke between the water and the ground....and see what kind of voltage and amperage is going through it. Just for curiosity's sake.....or at least information to let the electric company know what kind of stray voltage/amperage is floating around.

[Zapped]

Thank you the responses. It sounds like it could be a combination of old wiring (our house is 90yrs old) and being on the end of the line.

Thanks again, we will continue to try to chase it down.

[Dr. Spa]

I doubt it has anything to do with your homes wiring. But again, you can do a little test. Check for voltage between the spa water and "dirt", then shut off the entire main power to your home and retest for voltage.

If the voltage goes away, there's a problem with your home's wiring having a stray leak. If there's still voltage, you've proved it has nothing to do with your homes wiring.

[arnspa]

"Just because someone "is" and electrician, doesn't mean they have the experience, qualifications or knowledge to deal with an issue as rare or unusual as this (think OBGYN performing open heart surgery.....hey, he's a doctor, right?). "

___________

I really appreciate the exchange on this topic. When I had a concrete pad put in for our 1300 gal spa I failed to get the concrete guy to put in a link to tie the rebar to the ground I thought we would need there -- 50 ft from the main. And after, I had to insist to get the electrician to put a ground rod in at the spa switch box (50 amps).

About the analogy of electrician:surgeon, let me say, some GYNs are excellent surgeons. Last week my wife took a football sized ovary cyst from a 250 lb teenager through a 3" incision. But she doesn't do hearts.

Unfortunately, electricians aren't "board certified" as medical specialists are, and some are willing to underwire to give you a better bid, or are just unaware of the dangers working around water. Which is why we have permits and inspectors. You don't always get what you paid for, but you seldom get more than you paid for.

btw: Although my wife was the very first woman in the OB/GYN Dept at U of Virginia, about 80% of the GYN students she teaches now at Stanford are women. GYNS are likely to be she, not he. Power to them.