Electrocution in baptistry

[wwn23]

I am investigating an electrocution that occurred in a baptismal. The baptismal had a 120V water pump and 208V water heaters. Testing revealed that the source of the electrical contact with the water was the electric heaters. The victim was immersed up to the chest area and made contact with ground by grabbing a microphone. Another person was also in the water and was shocked when they grabbed for the microphone, but not seriously injured.

The heaters were assembled by a local electrician and mounted to the tub wall. The metal casing of the heaters was not bonded.

The local electrical inspector stated that there should have been a GFCI breaker installed. I found that there is no requirement for GFCI on electric water heaters in NEC 680, 422 or 427. Should there be? Is this important enough to be required in the NEC??

 

[bphgravity]

Re: Electrocution in baptistry

If the heater units are "hard-wired", there is no gfci protection required. It is possible that if the units are cord-and-plug connected, the receptacle they are plugged in requires gfci protection. This all depends on how the "pool" is defined by the AHJ and the insurance company. If indeed called a pool, 680 requirements would apply.

What concerns me is your statement about metal parts of the heater not being bonded to the effective fault path. Has it been established that an equipment grounding conductor was run to to the heater units?

What exactly was the fault or condition that took place in the heater?

 

[wwn23]

Re: Electrocution in baptistry

There was no EGC run with the 208V circuit, just 2 #10 AWG wires. The conduit was not bonded to the heater enclosure.

The failure mode of the heater element is still being investigated using x-ray analysis. It is suspected that the heaters were left on when the water was drained out.

 

[charlie b]

Re: Electrocution in baptistry

Originally posted by wwn23:Another person was also in the water and was shocked when they grabbed for the microphone, but not seriously injured.

Are you looking into this aspect (i.e., the microphone) of the tragedy? In case you haven't seen it, here is another discussion of an electocution in a baptismal font.

 

[wwn23]

Re: Electrocution in baptistry

While the microphone and cord are being examined, I can not understand how they could be anything more than a ground path. I have experienced leaky microphones when I was in a band and got a tiny shock when my lip made contact with the mic and my hands were on my electric guitar strings.

I took actual measurements from the water to ground with each item energized independently. The water heaters were making direct contact with the water, no question.

The fact that two people entered the baptismal without noticing the energized water is because it was electrically isolated from earth ground. The only bonded item in the baptismal was the water pipe, and the faucet was above the water level.

Only when someone in the water touched something grounded did current flow.

 

[iwire]

Re: Electrocution in baptistry

Originally posted by wwn23:
While the microphone and cord are being examined, I can not understand how they could be anything more than a ground path.

Internal fault in the mixer and or amp?

Lifted ground at the mixer?

I have no idea what caused the problem but it seems ruling out anything simply because you where in a band is not a great way to investigate this accident.

 

[realolman]

Re: Electrocution in baptistry

Since nothing in the tank was grounded, it seems to me that the heater would also have to have been bad in order for a faulty mic/ amp to have had a current path.

I don't think you oughta be getting into a tank of water with a mic/ amp under any circumstances.

An EGC probably would have avoided the whole thing.

 

[petersonra]

Re: Electrocution in baptistry

Originally posted by wwn23:
There was no EGC run with the 208V circuit, just 2 #10 AWG wires. The conduit was not bonded to the heater enclosure.

How would you manage to run conduit to a heater and not bond it?

 

[charlie b]

Re: Electrocution in baptistry

I really don't know how much help we can be. You are there. You have seen the setup. We can only guess. But for what it may be worth, here are a few more of my thoughts.

Originally posted by wwn23: While the microphone and cord are being examined, I can not understand how they could be anything more than a ground path.

Did you read the thread I mentioned in my first post. It was the mike, and only the mike, that caused that electrocution.

Originally posted by wwn23: The water heaters were making direct contact with the water, no question.

You might not be saying everything you know about the heaters, or you might not be saying it clearly. But water heaters are supposed to make direct contact with the water.

Do you mean that there is some part of the heater, some energized wire, that is making direct contact with the water? If the heater has not failed, if there is no short circuit between a wire internal to the heater and the case of the heater, then the heater is not the cause.

Originally posted by wwn23: Only when someone in the water touched something grounded did current flow.

That does make some sense. But how can you be certain that the pool is electrically isolated from Planet Earth? It does not take much to allow a fatal current to flow. A plastic tub in contact with wood flooring in contact with concrete slab in contact with dirt might easily provide enough of a path for current to flow from a faulted power source through the water and into the earth.

 

[George Stolz]

Re: Electrocution in baptistry

Originally posted by wwn23:
I took actual measurements from the water to ground with each item energized independently. The water heaters were making direct contact with the water, no question.

Same question: You mean you tested and the water heater conclusively read 208 Volts? What did you test with, a DMM or a wiggy? It's conceivable (especially without an EGC to the heater) that the voltage detected is induced, and not from direct connection.

Is the service neutral bonded to the water pipe? Is the water pipe metallic and continuous to the heater?

The fact that two people entered the baptismal without noticing the energized water is because it was electrically isolated from earth ground.

That would be a feat, no pun intended. The people entering the font would likely be barefoot. What is the material of the deck? I would think the step potential would be tremendous from the deck to the first step into the font. That step should be painful, if not bowel loosening, if not lethal.

The only bonded item in the baptismal was the water pipe, and the faucet was above the water level.

So the heater was part of a recirculating system not connected to the supply at any point? The seperate piping isn't bonded per 250.104? (Article 680 aside.)

 

[rattus]

Re: Electrocution in baptistry

wwn23, is this the Waco incident?

 

[wwn23]

Re: Electrocution in baptistry

Thanks for all the feedback. I'm a little reluctant to discuss all the details of this case since it is pending. My main concern is that something needs to be done to address this issue. Article 680 of the NEC doesn't specifically address baptismals; I think there should be a section added for baptismals in light of this incident.

I'll try to answer some of the questions that were posed. The baptistry is made of fiberglass. the decking around it is made of plywood supoorted by wood. The baptistry was about 4 feet above the concrete floor.

The soil pipe is PVC. The cold water supply is copper, bonded to the neutral bus at the service entrance. The installation is 60's vintage with no EGC - they relied on the EMT conduit.

I found no GFCI outlets anywhere in the vicinity of the baptistry.

The water pump was 120V and had a cord plugged into an extension cord which went into a non-GFCI outlet.

I have investigated several similar electrocutions involving pools and spas. They are all tragic and deeply disturbing. The NEC 680 has done much to address these fatalities, especially with regard to plug and cord devices and proper bonding.

The real issue is that the water heater was made by an electrician out of parts and pieces from a hardware store and wired back to the panel. It was a listed unit, just a home-made device that hung on the side of the baptistry, isolated from the world.

The conduit was not bonded to the water heater and the leads were simply taped up for the last ten inches or so from the cut end of the conduit.

This left the water heater without any recognized ground path.

The water heater was simply switched on and off from a disconnect switch without a thermostat or flow switch. It was effectively a tankless heater, but without any controls. I suspect the element was damaged when the baptistry was drained and it was left on.

I'll keep everyone posted as things develope. I sure appreciate your feedback and comments. They are very helpful.

Thanks everyone!

 

[wwn23]

Re: Electrocution in baptistry

I made a typo above, the heater was NOT a listed item, it was home-made by an electrician.

Also, the testing was done using a Fluke DVM. I placed one lead in the water with aluminum foil to increase contact area. The other lead was connected to the ground prong in a receptacle. First the pump was turned on and off, then each water heater (there were two). The voltage was zero until the water heaters came on, then it went up to 85V.

I had no way to test the microphone system as it was taken by the police. I have since collected it.

 

[rattus]

Re: Electrocution in baptistry

WWN23,

You might be measuring capacitive coupling with your hi-Z VM. You should place a resistive load across the VM to determine the level of current.

I would try 100K & 10K. 80V would generate 0.64Watts in 10K which would be a little much for a 0.5Watt resistor.

Sounds like you are on the right track.

Rattus

[ December 07, 2005, 09:50 AM: Message edited by: rattus ]

 

[wwn23]

Re: Electrocution in baptistry

Thanks again everyone.

I did read the thread about the microphone and cord and found it very informative. The only thing I wonder about is that the microphone system is still being used and the microphone in question was used almost daily with no report of shocks or tingling.

I understand that being submersed in water lowers body resistance.

I am looking into the microphone and cord system. The sound system was plugged into receptacles installed within the past five years which were connected to newer conduit with EGC. No GFCI though.

 

[don_resqcapt19]

Re: Electrocution in baptistry

wwn23,

I'm a little reluctant to discuss all the details of this case since it is pending.

This appears now to be involved with legal preceedings. The forum rules do not permit such discussions, so I am closing the thread. If this is not the case send me a PM. Thanks.
Don