Electrical Bonding

[cbridges]

I am just completing a new inground here in Canada, and my electrician seems to be up to speed with Canadian code, but I just wanted some confirmation. My pool is steel walled, vinyl lined. He wants the walls, the rebar under the deck, the ladder brace all bonded with no. 6 stranded bare wire, returned via conduit into the garage where my equipment is, and bonded to the pump housing. Then he wants all that returned via the same wire to the house's main panel (a real hassle and expense, since it will have to run through the attic, etc.). I guess my question is that, in the U.S., the NEC seems to be amended in 2005 with this: "...the 8AWG or larger solid copper equipotential bonding conductor isn't required to extend to (or attach to) any panelboard, service equipment, or electrode." In other words, the NEC simply seems to want all the metal bonded, but not run back to the panel, or even to the house ground, etc. So is my electrician correct about the Canadian stuff? Why the discrepancy? How about the difference in wire (solid vs. stranded, 8 vs. 6)? Any comments and insight greatly appreciated.

[mshumack]

It sounds like your contractor is going overboard. The pool equip, decking, and pool steel only needs to be bonded together. Furthermore, I was told by the electrical inspector specifically not to bond to the electrcical panel.

[cbridges]

Yes, that's my take on it as well. In fact, it seems in the U.S. that the NEC was specifically altered in 2005 to NOT have the bonding homerun to the panel. I am going to seek clarification.

[JohnT]

I know that the requirement is different in Canada. There has been much discussion and debate about the requirements in the US. Code is code, and you have to do what is legal.

[cbridges]

Absolutey. It's not my intention to do anything but. I guess I'm just trying to determine if this is, in fact, the situation in the U.S., and, more importantly, the situation in Canada. As well, legality is legality, but it would be interesting if Canadian standards are actually in contradiction to the revised (2005) American standards, particularly if it has more potential harm than good to homerun the bonding grid back to the panel.

[JohnT]

Absolutey. It's not my intention to do anything but. I guess I'm just trying to determine if this is, in fact, the situation in the U.S., and, more importantly, the situation in Canada. As well, legality is legality, but it would be interesting if Canadian standards are actually in contradiction to the revised (2005) American standards, particularly if it has more potential harm than good to homerun the bonding grid back to the panel.

There are situations where the ground could potentially make the setup more sensitive to stray voltage, but it really wouldn't be a safety risk. Unfortunately, there is not universal agreement on what is best.

[matt4x4]

grounding/bonding - all end up in the same place in your panel.
Bonding - to bring all metal in your house to the same electrical potential, should something like a cut extension cord conduct electricity to this bonded metal, the bonding wire (also a ground wire) will carry the electricity back to the panel, but because of the high amperage it will blow the breaker.

Grounding - allows for you to safely ground something like a lightning strike which is low current and won't blow the breaker, but has high voltage which can potentially end your life

Both bonding and grounding (terms are even used together in the NEC) physically end up in the same place, but react differently because of the different electrical properties associated with both.
When you bond your pool equipment as per NEC, you protect against faults in your electrical system possibly making the metal live.

Grounding, you protect against acts of God's electricity or other outside sources of electricity possibly making your metal live.

Bonding does not need a tick wire to be effective, but will work through a thick wire just the same.

Grounding does need a thick wire because it will melt the thin wire instantly due to the high voltage that would be incurred.

in the end, the thick wire satisfies both scenarios, where the thin wire does not - your choice.

Codes are different everywhere, just because the NEC states what it does, does not make it right everywhere, I think the CEC took acts of God into account, the NEC is only dealing with minimum requirements for bonding purposes only.

Remeber, these are MINIMUM requirements, tehre's nothing stopping anybody from going above and beyond these giudelines.

They specify to use #14 as house wire, this doesn't mean you can't UPGRADE and use #12 or even #10.

[tenax]

i just had a very qualified electrician whose done good work for me on other areas of my house check out my planned pool electrical and heating renos..i think he was smart to say,"

" i'm familiar with bonding and have done it but not since the code revisions..in the prior code it was not necessary to bond the pump , heater etc to the bonding grid, but..i'm going to bring an electrical inspector by to see what we are going to be doing and give me the final word"

that to me seems like the smartest route, right there..and yes, codes in us and canada are different on this as they are on ventilation. how different..not sure.

[matt4x4]

I looked into this last night some more, here's the results after talking to two certified electricians.
I printed off some of the stuff below from a website of FAQ's and had these electricians verify the integrity of the explanations.
I have pasted these explanations below and do not want to take any credit for explaining the two systems.

Bonding and Grounding end up in the same place but perform different functions as i have stated above, the function performed depends on what is happening electrically speaking.

Bonding explained - off web:

All "metallic systems" in a home that are capable of being
energized are required to be bonded to the grounding system.
This is usually taken to mean: metallic water supply, metallic
drain-waste-vent pipe, metal ducting, gas lines, and sometimes
metallic structural elements (eg: metal framing systems).

The rationale for this is simple: if somehow a hot conductor contacts
a water pipe, say, you don't want every plumbing fixture in your
home to become live. The bonding attempts to ensure that you have
a low resistance path to the ground system at the panel, and thence
to the neutral - ensuring that this ground fault is stopped by
a breaker or fuse tripping. Remember that this is independent of
the grounding electrode system's conductivity.

Normally the bonding of most of these systems are done by the
equipment involved. Furnace ducting is grounded by the furnace
connection. Gas line grounding is done by the gas man ;-)
So we'll mainly talk about water line grounding here.

The NEC appears to insist that each electrically isolated section
of metallic water pipe must be jumpered together. Take particular
note that you are required to provide a jumper wire that bypasses the
main water meter (especially if you're using the water supply line
as a grounding electrode), and a jumper between hot and cold if the
water heater is an electrical insulator. The CEC, for example,
also requires that the frame of your clothes washer is bonded to the
cold water supply pipe.

Here (clothes washer) you can already see the CEC is a little tougher on rules.

LOW RESISTANCE path means a conductor such as a wire.

Grounding explained - off web:

The grounding electrode system is a method by which the neutral
and grounding conductors are connected to the common "earth"
reference. The connection from the electrical system to the
grounding system is made in only one place to avoid ground
loops.

The grounding electrode system is not_intended to carry much
current. Ground faults (Ie: hot to grounded case short) are
conducted down the ground wire to where it is interconnected
with the neutral and hopefully the breaker/fuse trips. The
grounding electrode does not participate in such a situation.
While the conductors involved in this are relatively large, they're
sized for lightning strikes and other extremely short duration
events. The grounding electrode system is specifically not
expected to have enough conductivity to trip a 15A breaker.

The grounding electrode often has a moderately high
resistance. For example, according to the NEC, an acceptable
ground electrode system may have 25 ohms of resistance - only
5A at 120V, not enough to trip a 15A breaker.



So, judging by the explanations above, one can determine that:

This ensure that if you have a circuit in your electrical system short against a BONDED metallic system, the breaker will trip and if you have a lightning strike (external to your electrical system) hit your metallic system, that this lightning strike (low current, high voltage) will be safely carried to actual ground.

So, what it boils down to is the actual wire size running between your metallic systems and the panel - since bonding needs a LOW RESISTANCE PATH that is capable of carrying 110/220V with 15A of current, this can be done with a #12 wire, BUT, the same can be achieved using a #6 wire which would actually have LESS resistance than the #12.

For the grounding system, because of the high VOLTAGE that can be incurred, a larger wire (#8 or #6) is required since a #12 would melt instantaneously. Since the Ground electrode (actual ground rod outside the house) provides the resistance necessary to "automatically" differentiate between the two scenarios (grounding and bonding), the lower resistance of a #6 wire does not affect the functionality of the system.

Since most metallic systems are WITHIN your home, they will likely NEVER be hit by lightning, however, your Pool is OUTSIDE the home and thus has a higher risk of receiving a lightning hit associated with it.

So, in conclusion, to satisfy both scenarios at once, (killing two birds with one stone) use a minimum of #8 wire to tie back to the panel from pool bonding.
Use a #12 wire if you're not concerned about lightning stikes.

Both electricians I spoke to told me that the CEC takes the "two birds with one stone" approach, but could not verify the reasoning behind the #12 that is required by the NEC other than that they are NOT taking extenal high voltages into account.

It's nice to have friends in the right places who can shed some light on this type of stuff.

I hope the above information is useful to some of you trying to get a handle on this stuff, remember that code requirements are a MINIMUM and it is your choice if you want to go above and beyond these minimums, however, you do NOT have a choice to go BELOW these minimums.
In this case, personally, I would go ABOVE the minimum NEC requirements and go with CEC requirements.
Another couple of things I found out that were quite interesting - AG pools - being non permanent structures, do not require any of the above - doesn't mean you can't do it, but it's not required - fancy that!
On an IG pool, some type of electrode is required to ground/bond the water in your pool, this can be done by bonding a metallic pipe that carries the pool water, hoever, if your plumbing is Plastic, then you must have another electrode either inside the Plastic pipe, or have an electrode protrude into the pool low enough to accomodate the lowest water level normally incurred.


PHEW!!!! I need a beer!

[cbridges]

Matt, thanks for the excellent work. If I could buy you that beer, I would (Paypal?). It all makes sense. The part about the pool water being bonded -- can't find anything like that in the code! But it will be anyhow, as I am bonding my metal ladder, which always sits in the pool.

I also did some research with my electrian last night....we studied the three pages of section 68 of the CEC which deals with pools. Regarding taking the bond back to the panel, here is what it says: 68-058 (6): "The bonding conductor from the junction box referred to in 68-060 shall be run to the main panel, and if smaller than No. 6 AWG, shall be installed and mechanically protected in the same manner as the circuit conductors." Any interpretation of that?

Also, here's a curious one, regarding a GFCI circuit for the pump. 68-068 (7) "Except as permitted by Rule 68-070, the following equipment shall be protected by GFCI: (c) electrical equipment located within the confines of the pool walls or within 3 meters of the inside of the pool walls and not suitably seperated from the pool by a fence, wall or other permanent barrier." Well, guess what: my pump is located in my garage, about 4 meters from the pool, clearly behind a wall. So....no GFCI needed, according to CEC...which, in my opinion and my electrician's, doesn't make a lot of sense.

Go figger.

[matt4x4]

Here's what i get from that, first the smaller than #6 thing....
The junction box needs to be bonded, tehy would like to see a #6, however, if a #6 is not doable, then you need your Minimum to be equal and no less than the wire size of the wires feeding the junction box (circuit conductors) from the panel, which would make it the bare ground in your 2 wire #12 feed wire.

With regards to the GFCI - it's the hairdryer in the bathtub scenario here.
Since your pump can't possibly fall in the pool from inside the garage, and most likely can't get a continuous wet and conductive path to the pool, it no longer needs to be on a GFCI.
The part that doesn't make sense to me is the behind the fence thing, it's still outside if behind a fence and threfore should have a GFCI protecting it since if it shorts during a rainstorm and you're barefoot, standing on the wet ground beside it, you've just become part of the circuit.

Either way, go with a GFCI, obviously another one of those MINIMUM requirements that's just better to go the above and beyond route.

As for the water bonding, I don't know about what the CEC says, but I tripped across it somewhere on the NEC yesterday and it ended up in my pile of printouts I took home to review with my electrician buddies.

If you're bonding your ladder, it's more than enough since it drops deeper than the low point on the skimmer at which point without the ladder your pool water would be "disconnected" from the equipment.

Another way to do this is to bond one of the lower screws on the skimmer. Even though the wall and skimmer screws sort of meet and touch, this connection can fail and is likely not considered to be enough, that's why the NEC want a sepaprate bonding to the water, doing so on the skimmer screw/nut would provide a good solid bond.

As for the beer, I'll take you up on it (and a swim in your lightning safe pool) should I venture to BC one day!