Bonding Hot Tub Pipe

[Wgoodrich]

Roger, I have to admit a LITTLE BIT of hoosier hard headedness. However I believe the saying says you can't teach old DOGS new tricks. Now being an old dog I can handle but I am going to have nightmares concerning the OLD GOAT terminology. It might be a self analysis but I am sure I am much better looking than an old goat ! Then again that may be why I haven't looked in a mirror for a while, afraid I might be starting to look like an old goat. Uh.

Wg

[Roger]

Well maybe 'old goat' was a little extreme but I only have your avatar to go by....HA ... BTW that avatar is several years old...

It might be a self analysis but I am sure I am much better looking than an old goat !

That's just the politician in you! You did clean up pretty good for your campaign picture.... I would have voted for you for sure.

At any rate I'm actually thinking that we are just having a 'cool hand luke' issue with our communication.

I went over to the American spa and pool professionals website and boy are they having a lot of controversy over what constitutes water bonding for a hot tub...

Have a good day WG

[Wgoodrich]

Martyn

You are confusing the relationship of a grounding connection for the electrical system and a bonding grid system. A bonding grid system bonds any metal 4" square or larger within 5' of the hot tub or pool. This bonding grid is not designed to be part of any electrical premisis grounding system other than incidental connections through equipment. What you are discribing if I understand you right is to connect the metal parts of the hot tub to the equipment grounding using the electrical system grounding electrode to make an intentional connection to earth. This is not the intent of a bonding grid found in 680 of the NEC. A bonding grid is designed as an expotential plain so electricity can not flow from metal to metal through the water or other equipment of the hot tub or pool.

Copied section of NEC 2008 handbook commentary;

680.26 NEC commentary - As described in 680.26(A), the function of equipotential bonding differs from the primary function of bonding to meet the requirements of Article 250 in that providing a path for ground-fault current is not the function of the equipotential bonding grid and associated bonding conductors.

electrical system equipment grounding and a bonding grid aka expotential plane are two different systems used for different principles to enhance safety.

Roger, SueMarkup and I were discussing a fine point of the design of the bonding grid requirements not having the equipment grounding system of the structural electrical involved in the discussion at this time.

Wg

Vermont uses the 2005 NEC.

Hot tub water is not required to be bonded as it is with 2008 version...

Good idea?

Yes.

required?

No.

Under the International Existing Building Code, it would also be exempt from bonding requirements provided any repairs did not make it any 'less' safe than it already was...

[Wgoodrich]

There was a change between the 2005 and the 2008 NEC rules by adding the bonding of the water to the bonding grid system. The reason this was approached was a concern created due to changes in pool and hot tub design. There are pools out there now that comes like a great big plastic or fiberglass tub with no metal on contact with the water. Then concerning transient voltages and leakage in motors associated with the pool or nearby underground power cable introducing power into the nonmetallic tub. This condition sets up a person in the water to be energized without them knowing it and nowhere for the current to flow to. Bonding the water with the bonding grid that is any metal part within 5' of the hot tub or pool keeps the potential equal in hopes to keep nowhere for the current to flow. The minimum area in contact with the water is 9 square inches which would equal a 3"x3" contact metal with the water. Normally this is done naturally by an inline heater metal casing of a motor or heater etc. However there are major discussions about what is adequate contact with the water.

The new rule is a good thing in reaction to changes in the designs of the pools. Many pools even have nonconductive fiber light thus eliminating even the bonding attachement of the a wet or dry niche that would make contact with the water. Just check to see if you have contact of a minimum of 9 square inches with the water. Then you have met the 2008 being more stringent than the 2005. In a hot tub most inline heaters are about 3" in diameter and about a foot long. The water from the pool or hot tub flows through that heater as the water circulates. This would meet that rule. It really is not hard to meet that rule in the design. It is just a change to address a new concern due to nonmetallic pool and hot tub designs getting more popular.

Wg

I applaud Wgoodrich for his gracious ability to explain without hostility the differences between the US 2005 and 2008 National Electric Code regarding swimming pool bonding....

I also applaud the gracious acceptance by Martyn to admit that UK and US standards for 'pool' bonding vary markedly....

Good Show!

To BOTH of you!