Did we have the conversation before or not. I can't remember, there have been so many topics covered here.

If you place a hot tub/spa outside on a wooden deck and the deck is up in the air off the ground. ( height doesn't matter) What do you do with the equipotential bonding grid? (EBG) Do you run it around the tub under the deck? Or leave it out completely? Or what?

If you read the letter of the code, you still need to bond the dirt under the deck or if you read it the other way you have to bond the wood. Non-conducting decking is really not addressed, nor is it excepted.

I think CMP 17 has been snorting the HTH.

Harold:

This is a tough one IMHO. Conflicting 'he said/she said', and a gray area within the NEC.

There are differing opinions on the conductivity of wood, which I don't want to debate, although someone will. Composite decking is also a debate by some.

Opinions that I have heard range from the absurd (IMHO) of 'bonding the wood' to ....nothing.

Most spas that I have seen install the rubber type listed mats under and around the spa; case closed.

Installs on existing concrete or paver patios are another tough call. Bonding the existing rebar/mesh is one option, the pads is another, or the grid around the slab. Problems arise when the 'slab' is a large patio. Solutions range from finding the rebar/mesh to saw cuts & #8, or..the pads.

Welcome to confusion!!

Now try to explain this statement to Joe Handyman:

"We'll laugh ourselves silly when we find you ran a GEC to the incoming plastic water line, but we'll red-tag you if you fail to bond the plastic deck."

Has anyone written a proposal yet?

apparently the CMP's insist on one shoe fitting all

for instance , would you feel comfortable installing a grounding grid under a spa that is in proximity to the service entrance g'ding electrodes?

~S~

Why not? The pool/spa ground grid is going to be bonded to the EGC of the supply conductors in a number of places and that is bonded to the GEC.
In the case of a gunite in ground pool, that is ultimately you best grounding electrode, even though we are slow to admit it.
If it is concrete or metal at my house, it is bonded.

well my point is , it's a potential noodle Greg

i mean, the more we bond, ground, lightning 780, or EGC a place, the more noodle potential it will have....~S~

Noodle?

Greg:

That's a common term in some areas for 'neutral'.

The GFCI pretty much eliminates that "noodle" problem in any circuits near the pool. I GFCI every circuit that leaves the house, even the things like luminaires that don't need it.
The code will catch up them soon anyway.

As long as everything is bonded together, it really doesn't make much difference what potential you are sitting at, since everything else is right there with you. That is why we have all of those rules in 680.26

Hey it's my B-Day, just got a "Happy Birthday" greeting from the ECN. Thank You whomever sent it.

As for this issue there is a TIA that came out in March of this year and it says:

680.42(B) Bonding. Bonding by metal-to-metal mounting on a common frame or base shall be permitted.
Exception No. 1: The metal bands or hoops used to secure wooden staves shall not be required to be bonded as required in 680.26.
Exception No. 2: A listed self-contained spa or hot tub that meets all of the following conditions shall not be required to have
equipotential bonding of perimeter surfaces installed as required in 680.26(B)(2):
(1) Is installed in accordance with manufacturer’s instructions on or above grade.
(2) The vertical measurement from all permanent perimeter surfaces within 30 horizontal inches (76 cm) of the spa to the top
rim of the spa is greater than 28 inches (71 cm).
Informational Note: For further information regarding the grounding and bonding requirements for self-contained spas and hot
tubs, see ANSI/UL 1563 – 2009, Standard for Electric Spas, Equipment Assemblies, and Associated Equipment.

I'm also big on GFCI's Greg. But the practical application in areas lousy with objectionable currents due to over zealous grounding has been a problem for me

~S~

bravo!

~S~

How can "over zealous grounding" cause objectionable currents as long as you are not regrounding the neutral somewhere and a GFCI pretty much eliminates that anywhere on the load side of the device.

For the purposes of this discussion we really should be saying "bonding" though.

Happy birthday George!

Greg,

OK, we are all in favor of safety and grounding and GFCI. However what would putting a #8 bonding wire under a wooden deck really do for safety?

I don't think I would bond a wooden/plastic wood deck, nor would I make an installer do it. 90-4 swings both ways.

Greg:

I agree with you 100% on the above.

On this subject, an interesting question this AM ."The tub is only 2' from the exterior wall of the house, can I cut the mat, or must the tub be moved"? Followed by....."do I have to install a 'bond' on/under the cedar shakes"?? Ya gotta love it!

because contrary to the doctrine , the earth itself can be a return path Greg, doesn't mean the Hot tub is the culprit, just the victim ~S~

I understand the earth can be a ground path and the whole pool, spa, screen cage, deck, pumps and cover may be somewhere above zero volts compared to some theoretical ground but it will all be the same amount above zero volts if everything is bonded together.

680.26(A) says it all



"Ground" is really pretty meaningless anyway. I have seen 35v between the ground electrode systems of 2 buildings (on my Dranitz). We ended up bonding them together to stop stuff from blowing up when we strung data cables between them.

ok, so what we have is a code consession Greg, due to 680.26 trumping 250.6 (note HB commentary, and 250.6D's commentary)

that said, this immovable NEC mobius strip logic does not mitigate the underlying irresistable electrical theory via the introduction of componets becoming inversley proportial to their intended goals

~S~

Greg,


I got it! I just thought of the perfect solution! I will router a line all around the hot tub on the wooden deck, stick the #8 bare in there and putty it all up, so that no one trips over the wire. Neat right?

And if it comes to a composite deck, I can use a hot knife to melt a track in the deck around the tub.


You know I am just kidding right?

There is no conflict between 250.6 and 680.26.

You are still supposed to separate the neutral from the EGC anywhere on the load side of the service disconnect so you should not have any circuit current in the EGC.

Any current you see in the EGC is going to be between separate services and technically it will be on the line side of the EGCs. We tend to deny that exists and it is not in the scope of the NEC.
I had a big dust up with an FPL guy one day when he said there was no current flowing through the earth from their wye distribution services. He simply did not understand the idea that current takes ALL paths. I showed him there was an amp or two flowing in the ground wires running down his poles and he still denied that was current flowing through the earth.
This one had almost 3 amps

well while you're describing a GEC vs. an EGC correctly, mine would be they do not exist exclusively

or put otherwise, one may try and do the other's job , in that you 'EGC' a large piece of anything to earth , especially in the right path, and it may well become one of those 'all paths' you speak of

~S~

I agree the GEC does become part of the distribution system but as long as everything on the load side of the MBJ is isolated from the neutral there should not be anything but fault current flowing and that should quickly operate the over current device. Outside it will certainly trip the GFCI

yes Greg, but let me pose a scenario.

Said GFI trips while the spas aren't even in operation

Naturally one would wonder about this.

Consider all ECG's and GEC's could be (and often are around here) married to the panel MBJ noodle bar

I suspect this is why the nec put (the old) 250.32B out to pasture, but the same phenomenon that inspired them to do so can still exist bettween dwellings, and even within dwellings.

consider, for example the old 3 wire dryers and stoves which bond noodles to their shells

~S~

I would like to get involved in the investigation of a GFCI tripping with no load present.

I would like to get involved in the investigation of a GFCI tripping with no load present.
It would scream, "regrounded neutral" to me.

The code pretty much dictates that the grounded, grounding and GEC all get connected together in the service disconnect can. The only time this is not true is when the GEC lands somewhere else on the line side grounded conductor.
It still does not change the fact that the grounded and grounding conductors should never meet again.

agreed on all counts Greg

i'd only state that we've a lotta old, and mostly uninspected wiring in Vermont.

for instance, we're lousy with 'subpanels' without a floating noodle

they all seem to fall under that 'existing' black hole

which is often the bane of my existence, being i end up the 'bad news guy'
~S~