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[John Roberts {JR}]

So we all are thinking improper grounding?

How do we close the safety loop and save a life?  Email to AHJ?

Or do we just start a thread in ten years time titled "Hey, remember that hot tub thread, you'll never guess what..."

See something?  Say something.

There could be natural sources of small currents, but to repeat myself check to see if it is 60Hz? That would clearly not be from the earth's magnetic field or solar flares. In fact (steady?) AC seems unlikely from any natural source.

A simple test I would perform would be putting some long leads on a VOM, and probing around to see where the energy is strongest, that may lead you toward the source. If possible one lead of the VOM grounded to electrical safety ground.

JR

PS: For extreme cases a buried wire grid (like a ground plane under a broadcast antenna) could capture the leakage, but that seems extreme, perhaps a few well place ground rods could reduce the exposure to meat puppets.

[Mike Sokol]

Others have repeated theselves  so may I?  Not improper grounding, but improper bonding..

It is pretty worrisome that the hot tub owners have put in writing not to worry about small shocks. That's just crazy and opens them up to all sorts of lawsuits if someone is injured or killed in or near one of these hot tubs.

So I was thinking about this entire situation last night as I was adding a ground/bonding wire in my home service panel to the plumbing. And one of my kids who was assisting was asking why we had to bother to "ground" the plumbing when it went into the "ground". I showed him that only part of the house plumbing was copper and the rest was plastic, so we had to be sure that all steam pipes, gas pipes, water pipes and duct work had to be bonded to the same potential as the service panel neutral, or it would be possible to "electrify" the water going into the bathtub upstairs. That is, a plastic water pipe essentially acts like insulation around a conductive wire. That suggests it's possible that the bonding point of the water supply feeding the hot tub might not be connected to the service panel properly. It's also possible that the hot water heater feeding the hot tub might have a pin hole leak in the sheath, which I've personally measured at a few amperes of current flowing into the water. Of course, that would create a voltage gradient between the incoming water pipe and any "bonded" metal in the tub such as the drain plug.

Someone needs to get a meter on this thing to see exactly how much voltage is being measured and between what. We all know that even a 9 volt battery on the tongue will get your attention, so if your standing in a chlorinated water puddle I'm sure you can feel even 2 or 3 volts. But the hint is that something is really wrong with the ground-bond in this installation and that 2 or 3 volt moderate shock could turn into 20 or 30 or even 120 volts at any time. And that's killer voltage.

I wonder just who wrote up that sign? Some marketing committee maybe? I can't believe any inspector would have signed off on that.

[John Roberts {JR}]

It is pretty worrisome that the hot tub owners have put in writing not to worry about small shocks. That's just crazy and opens them up to all sorts of lawsuits if someone is injured or killed in or near one of these hot tubs.

So I was thinking about this entire situation last night as I was adding a ground/bonding wire in my home service panel to the plumbing. And one of my kids who was assisting was asking why we had to bother to "ground" the plumbing when it went into the "ground". I showed him that only part of the house plumbing was copper and the rest was plastic, so we had to be sure that all steam pipes, gas pipes, water pipes and duct work had to be bonded to the same potential as the service panel neutral, or it would be possible to "electrify" the water going into the bathtub upstairs. That is, a plastic water pipe essentially acts like insulation around a conductive wire. That suggests it's possible that the bonding point of the water supply feeding the hot tub might not be connected to the service panel properly. It's also possible that the hot water heater feeding the hot tub might have a pin hole leak in the sheath, which I've personally measured at a few amperes of current flowing into the water. Of course, that would create a voltage gradient between the incoming water pipe and any "bonded" metal in the tub such as the drain plug.

And you could tell them you know a guy (me) who felt an electrical shock from his shower.  when his hot water heater element casing rusted through.

BTW confirm that your HW heater chassis is grounded too... My plumber didn't bother when installing my new one, he just connected the two hot leads coming from the wall.

Someone needs to get a meter on this thing to see exactly how much voltage is being measured and between what. We all know that even a 9 volt batter on the tongue will get your attention, so if your standing in a chlorinated water puddle I'm sure you can feel even 2 or 3 volts. But the hint is that something is really wrong with the ground-bond in this installation and that 2 or 3 volt moderate shock could turn into 20 or 30 or even 120 volts at any time. And that's killer voltage.

I wonder just who wrote up that sign? Some marketing committee maybe? I can't believe any inspector would have signed off on that.

I'll bet some probing around identifies the culprit...  For the local government to tell people to ignore shocks, is shocking.

JR

[Stephen Swaffer]

PS: For extreme cases a buried wire grid (like a ground plane under a broadcast antenna) could capture the leakage, but that seems extreme, perhaps a few well place ground rods could reduce the exposure to meat puppets.

I would agree that a grid seems extreme-and also impossible to implement after the fact.  I simply listed Code requirements.  I don't know if stats drove this or if a contractor specializing in such installs pushed for its inclusion.  Obviously, the closer you get to this "ideal" the better it will be-the question being how much better is better enough? (The answer to that, if it is my grandkids is, "can it be better enough?"   )

The pinhole in a heater element is also the root cause of the baptismal shock from a few years ago-if my memory serves me correctly.  Bonding the water might have caused a breaker to trip in that case-it most certainly would have tripped a GFCI (had one been in place)-which is a much safer scenario than letting the pastor be the conductor tripping the GFCI.

[Mark Cadwallader]

(Snip)

  For the local government to tell people to ignore shocks, is shocking.

JR

The written material that says that the ground currents at hot tubs are (usually) nothing to worry about was written by a property management company, not a local government. It's a "don't bother us, we don't care and won't do anything" paragraph.

[Mike Sokol]

The pinhole in a heater element is also the root cause of the baptismal shock from a few years ago-if my memory serves me correctly.  Bonding the water might have caused a breaker to trip in that case-it most certainly would have tripped a GFCI (had one been in place)-which is a much safer scenario than letting the pastor be the conductor tripping the GFCI.

Yes, that's a reason for a number of baptismal electrocutions, as well as dozens of RV hot-skin conditions that I've discussed on my RVtravel column. I've created this pin-hole hot water heater condition on purpose and found that you'll get maybe 1 to 2 amperes of current flow into the water if the tank is bonded. And remember that a glass-lined hot-water tank will tend to direct the fault current to the inlet and outlet pipes, NOT the surrounding tank itself. So it's plausible that this fault current could find its way into your plumbing system and eventually a shower head or hot tub.

And here's the original story that got me interested in shower electrocutions. http://www.cnn.com/2008/US/05/28/soldier.electrocutions/index.html?_s=PM:US
It's bad enough that the enemy is shooting at you, but to be electrocuted in the shower is horrible.

[Ed Hall]

I appreciate everyone's responses.

I suppose I'm guilty of what several have done before. I made my decision, to not allow the kids in the tub, then came here looking for validation of my decision.   

I've have and continue to learn a lot from these boards. It's the reason I knew what the tingle was, how to check it, and to not let anyone in when I couldn't correct it. It was only about 6 VAC with no detectable current...at the time I checked! Who knows what it was the day after or the next! I know enough about electricity for my little sound business.  I also know when not to mess with it, like at a rental property, that I don't own and am not licensed to work on. And in case anyone was wondering, the drinks were just as cold on the deck all week long!

We did notify the rental management company when we left. Being that they put a paragraph in their renter's booklet addressing it, I doubt anything will be done.

[Frank DeWitt]

You might want to send the rental company a copy of this thread.  It shows them that it is "out there" and therefore they have less cover.  If it was me, I would name them.

[Stephen Swaffer]

Re-reading the OP begs another question.

Was the hot tub breaker a GFCI (did it have test button on it)?

If not, I can almost guarantee you it was replaced because of "nuisance" tripping-that was really a red flag that there was a real problem lurking.

[Tim McCulloch]

Others have repeated theselves  so may I?  Not improper grounding, but improper bonding..

An equipotential bonding grid requires a copper #8 connection between these:

1.  Re enforcing steel or #8 copper grid on 12" centers bonded at every crossing
2.  Perimeter surfaces-same as shell
3.  Metallic components
4.  Underwater lighting
5.  Metal fittings
6.  Electrical equipment
7.  Fixed metal parts (within 5' of pool)
8.  Pool water.

Interestingly,  this bonding doesn't have to be extended back to a panel-short of other bonding requirements for electrical equipment.  It is intended to make evryting you can touch essentially one "wire".  If you can't touch parts (including water) at different potentials you can't get shocked.  (With modern plumbing, water can be completely isolated with plastic piping-so water is a 2017 addition-probably not enforced hardly anywhere-but the OPs experience may illustrate the purpose for the new rule).

This is obviously an extreme synopsis-don't use this to design from!  The biggest issue I have is the property owners characterization of this as "normal".  Lightning is "normal" too!

I took the time to type this because it is an illustration of what should happen in any sound/entertainment scenario-albeit without the extreme copper mesh.

About 18-20 years ago I saw a very literal star grounding system, I think on either a Clair or ShowCo rig.  The 4/0 EGC from the company switch terminated to a large copper plate at soundco's main distro that became the grounding bus.  All EGC from sub-distros terminated there, as did separate conductors bonding the staging frame and the metal rails of amp racks.  Back in the day before cellphone cameras or I'd have a pic of it... but I think this is a remnant of addressing the Pin 1 Issue via heroic copper means.

I'm having a flashback to what it took to interface stuff 25 years ago - a whole lotta stuff, usually - and make it quieter than ambient noise in a room designed for athletics.  <shudder>  We have it so much better these days. 

[ProSoundWeb Community]