Electrical for new pool

Jump to latest Follow Reply
Ok, I went back and reviewed the NEC. You are right, bk406, a #12 insulated ground is required for the pump if it is run outside of the dwelling unit. Anything inside the house can be uninsulated. My area requires a GFCI breaker or receptacle, but I do not see that it is required unless it is cord and plug. I personally wouldn't have a pool that is not GFCI protected. I also would always drive a ground rod although it doesn't appear to be required by the NEC.

As far as running the pump at 120v, I would like to hear a reason why this would increase the temperature it would run. I have never heard of this before and I have quite a bit of experience with motors. Please educate me.
 
Lower voltages mean more power lost to resistance in the wires, which means more heat. How much more heat will vary, depending on assorted design details. In any case, the actual temperature and lifetime differences are fairly small under normal conditions. The primary issue with using 120v is that you will lose more power to the wiring runs between the motor and the main circuit breaker panel than you would at 240v. This is especially true for larger pump motors and longer wiring runs. With 20' of wire and 1/2 HP motor it doesn't matter much. With 150' of wire and a 2 HP motor it makes a significant difference.

Adding an extra ground rod that is not required can cause problems, both practical and safety related, if there are any significant ground currents. Which is to say that it has both advantages and disadvantages. A properly installed bonding system will provide electrical safety for swimmers, regardless of presence or absence of a ground rod.
 
Couple reasons. One romex isn't designed to get wet. The insulation and the paper inside isn't supposed to get wet. Conduit will get wet inside; no way around it.

The second reason is not really related but its the reason you can't run romex for a pool. The ground in romex is bare. Pool wiring requires an insulated ground.
 
i found this.

1. Revise 680.26 (C) & 680.26 (C)(1) as follows:
(C) Equipotential Bonding Grid.......

Exception: The equipotential bonding grid shall not be required to be installed under the bottom of or vertically along the walls of
vinyl lined polymer wall, fiberglass composite, or other pools constructed of nonconductive materials. Any metal parts of the
pool, including metal structural supports, shall be bonded in accordance with 680.26(B). For the purposes of this section, poured
concrete, pneumatically applied (sprayed) concrete, and concrete block, with painted or plastered coatings, shall be considered
conductive material.

My planned pool is polymer walled vinyl lined with one ladder and a composite wood deck. As I described in another thread, the pool is in ground, with 18 inch walls above ground, so the deck will be 18 inched above ground set on concrete deck blocks. Will these have to each be bonded? I will be building the deck after the pool builder is gone. if the pool is bonded correctly, will the addition of the deck affect it? When researching pool deck plans, i have never run into any mention of bonding the base blocks.

Dan
 
Polymer walls don't have to be bonded. The exception is added since this type of construction is relatively new. I honestly couldn't tell you if concrete piers for your wood deck need bonding. I wouldn't think so but that's something to ask the electrical inspector
 
Likely not the deck, but as BK said check with your inspector, but if the ladder is metal, it will need to be bonded.

I can't find it at the moment, but the is a LONG thread here with a member that was going crazy due to a stray current...I'll try to find it, but it's why you see we are kind of passionate about this stuff :wink:
 
woods780 said:
I also would always drive a ground rod although it doesn't appear to be required by the NEC.
Click to expand...

Not only is it not required by the NEC, they specifically note that it's not required, which is unusual.

Canada requires the bonding system to be directly grounded.

I was told that the grounding rod on the bond wire makes the pool safer in the event of a nearby lightning strike, while the lack of a rod makes the pool a little safer in the event of a power line falling nearby, an electrical appliance on a non-GFCI circuit falling in the pool, or a major electrical supply malfunction.

I'm not likely to be in my pool when a thunderstorm is anywhere near, but an electrical mishap can't be predicted.

Since the bonding system is connected to the supply ground through the pump motor housing, adding a grounding electrode results in multiple grounds on the system, which can cause unanticipated currents.


Dan, as far as the piers needing bonding, I don't believe so. An inspector might disagree. NEC doesn't require bonding for things inside a house, and I think your piers are under the same "spirit" of the code. They are inaccessible.

When in doubt, I believe this is the gist of the bonding requirement:

1.) If something is permanently mounted, conductive and bigger than whatever minimum size 680.26 says (I can't recall right now) and a person can dip one toe in the water while touching the object, it must be bonded. Unless it is inside a structure.

2.) If something is conductive and it is in contact with or could potentially come in contact with the pool water, it must be bonded.

IMO, your piers are out of reach of a bather. Whether wet composite wood is considered a conductor, I don't know. If you are talking about something like Trex, I think you are fine.
 
JohnT said:
Since the bonding system is connected to the supply ground through the pump motor housing, adding a grounding electrode results in multiple grounds on the system, which can cause unanticipated currents.

.
Click to expand...

You got it. The pump (or heater for that matter if you have one) is grounded to the main panel. If a bonding wire that is attached to the pump motor housing is also grounded with a rod, it makes more than one path back to ground, unintentionally. It's the same reasoning why a sub panel has the bonding strap removed between the neutral bus and ground bus. Only ONE path back to ground is warrented due to the possibility of ground loops and stray currents. As I said earlier, the only exception is a sub panel thats not attached to the same structure as the main panel. Then, a second ground rod is required, but the neutral bus is still disconnected from the ground.

dpoelstra, you had no idea we could get this far down the road into pool wiring from your initial question huh? :lol: :lol:
 

Enjoying this content?

Support TFP with a donation.

Give Support
It varies from place to place, but many areas require a buried bonding wire all the way around the pool in a situation like this one, ie when there is a non-conductive pool surround. If so, it should be #8 solid copper, buried 4 to 6 inches below the top of the sub-grade and 18 to 24 in out from the water. Occasionally you also have to have a buried conductive grid that extends out 3 ft from the water all the way around, though that is not so common when there is nothing conductive in the area.

This is an area where it really helps to either find someone who is familiar with the specific rules and how they are applied by the inspectors in your area or to talk to the inspector in advance about what the requirements are. There are a couple of different editions of the NEC code in active use and often enough there are local variations as well. The most recent edition of the code, not yet in use in most places, also requires that the water be bonded via a section of conductive pipe, which is generally a good idea in this situation even when it is not required.
 
Ah, the grid. Everyone grab yourself a cup or bottle of something appropriate - I'm probably gonna ramble a bit.

Bond. James Bond. No, sorry. POOL Bond.

I'm gonna chime in and say that I believe that any non-portable pool over 42 inches depth requires an equipotential bonding grid. Realize that this is NOT designed to "ground" anything. It is designed to connect any and all conductive surfaces of the pool proper so that no one element may, in any fashion, ever be electrically at a different potential than any other element of the pool proper. This means that if any piece is at ground potential, all of it is at ground potential, and if any of it is at 120VAC potential, all of it is at 120VAC potential. That's pretty much the sole purpose behind it, the reason being so that you cannot receive a shock by touching two parts of the pool. That covers the reason and intent - I hope it is clear.

As to the physical requirements, I will state up front that I am not as well versed with the code for pools as I probably should be, but meh... whatcha goin' to do, right?
At the core, You should have #8 copper attached to all metal/conductive surfaces of the pool. There are NEC requirements and restrictions as to not having wiring under the pool, how close to a wall the wire can traverse vertically vs. horizontally, and such, but the practicality is that the ONLY important requirements are as follows 1) You must provide sufficient bonding to satisfy the AHJ (Authority Having Jurisdiction), and 2) you must make certain that ultimately, you, your pool guests, and your home are safe from pool-related damage and injuries. Pool guys and electricians and engineers and local handymen and second cousin's wife's office manager's uncle's fiance's old boyfriend or whoever can tell you exactly what you must have or must not have, but if the inspector claims something else, you will not get a permit. Period.
That's assuming that you need a permit, and in most places, you do, even if you think you can sneak by under the radar.

Most inspectors are not idiots, and are generally well trained, if not better qualified than many knowlegable electricians. I certainly hope yours is. Occasionally, stories arise about a ... um... less than optimally qualified inspector demanding something that doesn't seem right. Either way, he or she must approve your install. It will be far easier to seek out your AHJ (inspector) and arrange a time where you can just ask what the requirements, best practices, and his personal recommendations (you know, 'cause of all his experience...) and get yourself the best chance of a positive inspection result the first time. He would probably love to tell you some tales of some of the nightmares he's had to deal with. Probably good for a couple of cups of coffee, some funny stories, and a good rapport with the one dude who can stop your build cold. Your mileage may vary.

I also have to mention that sometimes, people can simply be sticlkers for very strict interpretations of the written code, and you may find yourself with an AHJ who demands that you have some odd fiberglass part bonded, or some such meaningless garbage, because "The code states that the SHELL MUST BE BONDED" or such. If you do, I'd suggest that you don't argue. Ask why, you know, so that he can enlighten you with that experience and knowledge we talked about earlier, and then just do it. Find a screw somewhere on a rib and connect a grid wire to it. Take a picture of it, though, so that after you have your permit, and your pool is complete, you can share your own story. Don't go laughing around town or the internet until you have everything done, though. Trust me on this one.


OK. Sorry for the soapbox sermon. I'm done for now.
 
JohnT said:
Since the bonding system is connected to the supply ground through the pump motor housing, adding a grounding electrode results in multiple grounds on the system, which can cause unanticipated currents.
Click to expand...
The equipment ground is also connected to this. Since a ground takes the path of least resistence, I would assume that the bare #8 bonding wire buried and connected to the pool would become this path and not the #12 wire to the house panel. I know the purpose is to keep everything at the same potential. This is another reason I always want the pump to be GFCI protected.


JasonLion said:
Lower voltages mean more power lost to resistance in the wires, which means more heat. How much more heat will vary, depending on assorted design details. In any case, the actual temperature and lifetime differences are fairly small under normal conditions. The primary issue with using 120v is that you will lose more power to the wiring runs between the motor and the main circuit breaker panel than you would at 240v. This is especially true for larger pump motors and longer wiring runs. With 20' of wire and 1/2 HP motor it doesn't matter much. With 150' of wire and a 2 HP motor it makes a significant difference.
Click to expand...
This is why you derate the wire for longer distances (the resistence also causes voltage drop). I would imagine there are very few instances where a temperature difference could be measured in a pool scenario or with even a small 2 hp motor and 150' with the properly derated wire size.
dpoelstra said:
bk406 said:
Sounds ok. I still have issue with romex in conduit.
Click to expand...

I am not arguing here, I am just very curious why romex in this application is so bad :?:
Click to expand...

bk406 said:
Couple reasons. One romex isn't designed to get wet. The insulation and the paper inside isn't supposed to get wet. Conduit will get wet inside; no way around it.

The second reason is not really related but its the reason you can't run romex for a pool. The ground in romex is bare. Pool wiring requires an insulated ground.
Click to expand...
Right and because NEC 680.21(A)(1) says so, outside of the dwelling unit.


Great discussion. I have definitely learned some things. :cheers:
 
woods780 said:
The equipment ground is also connected to this. Since a ground takes the path of least resistence, I would assume that the bare #8 bonding wire buried and connected to the pool would become this path and not the #12 wire to the house panel. I know the purpose is to keep everything at the same potential. This is another reason I always want the pump to be GFCI protected.
Click to expand...

It would depend a lot on soil conditions, electrode conditions and maybe even the way you hold your tongue as to whether the bond wire serves as the ground. It's often in gravel backfill, and even when in the soil it is near the surface. Both situations will be dry during much of the swimming season in a typical installation.

Like you say, the equipotential is the key. You and I are at +/-50,000V right now, referenced to something. As long as we don't touch that something, we are good. :shock:

When I installed my pool, I used a GFCI breaker for my pump, even though code didn't require it at the time. A properly installed bonding grid could hide the effects of a ground "leak". Even though it would protect you, I like the second layer and the warning you get from GFCI trips.

The NEC changes as situations arise that nobody anticipated, and 680.26 has been changing quite a bit lately. That should tell us that this isn't a simple concept.
 
JohnT said:
680.26 has been changing quite a bit lately. That should tell us that this isn't a simple concept.
Click to expand...

True enough. When my pool was built, Massachusetts didnt require a mesh bonding grid under pavers that is tied into the rest of the bonding circuit. I believe now they do. But, from what i hear, a lot of inspectors (good ones by the way), dont enforce it unless there are underground power lines within so many feet of the pool. Am I going to rip up everything to put one in? I dont think so since I consider what I have to be safe. As Jason said in an earlier post, now the water is being bonded :shock: . A study I ran across that was put out by IEEE showed that a drop in pool had some stray voltage hanging around and if a metal disk (9"x9") was attached to the bonding wire, the potential went to zero. That got the NFPA thinking about it and the idea it ought to be a part of the NEC. Some discussion i've seen says that if you have a ladder IN the water and the ladder or anchors are bonded, its as good as having the water bonded (I actually think this is true, but I'm not looking for a discussion on it. :wink:

Believe it or not, the NFPA (national fire protection association) who writes the thing is a private organization; they are not a government entity. The NEC is really a SUGGESTION, but authorities having jurisdiction (AHJ) usually adopt it. However, realize a lot of towns/cities/states are 1 and even 2 versions behind (they come out with a new one every 3 years). It's also over 1000 pages :shock:
There is no way that you can keep up with it and even modify a small portion of the changes to make existing "stuff" code complient. The best thing to do is to try and do things as close as possible and realize that some of this stuff can be over kill. Even really good electrical inspectors "overlook" things from time to time since in their experience, the NEC is some areas is overkill. (Same for other trades too. Plumbing inspectors overlook a few things here and there tas well). Do I really think putting romex in conduit is gonna result in DEATH, DESTRUCTION AND MAYHEM!!!?? LOL. Not really, but it can be a safety issue under certain circumstances. Like Ohm boy, i guess i'm done....for now :wink:
 
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply