SWG AGP, ladder rusting - earthing & bonding query

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M

mister_rossi_x

Active member
Apr 10, 2024
32
Leicestershire
Hi all

I have an above ground pool - 4m x 2m, wooden frame with metal braces. Covered by a polycarbonate polytunnel - i.e. rain and leaves kept out.

An electrician fitted outdoor sockets back to an RCD for the devices that are plug & play (filter pump, SWG) and hardwired the heat pump and the Aquajet (counter current system for swimming).

My problem is that my stainless steel (marine grade) has rusted. I'm being told (supplier/manufactures) that this is a combination of the SWG and a "stray voltage" and that I should do the following:

Earth the ladders at the very least
Earth the ladders and any other electrical equipment that’s within the plant room to a copper ground stake
+
"It’s no good connecting to the house earthing ring unless its in conjunction with a ground stake"

or

Consider fitting a sacrificial anode.

I've done some research and it seems there's a general recommendation (although it's debatable whether it's needed for an above ground pool) to BOND the pool too.

This hasn't been done and I'm not 100% sure it's necessary for an AGP / my scenario, nor how it relates to the above recommendations?!

So my question is: what do I do to resolve the rusting ladder situation, given:

Outdoor pools in the UK are a rarity and no local electrician seems to have a clue about any of these subjects
There are no local pool experts
Pool experts are extremely expensive here
I'm very low on funds!!

I believe I could source a "copper ground stake" myself and install in the ground, and connect the ladder to this.
Does that DO anything, or do I also need to connect to the "house earthing ring"?

The equipment in the plant room are surely already earthed - both the hard wired and plug and play; the UK uses a 3-pin system with an earth. But do I need to connect this copper stake to the earth (in which case I need an electrician) or is that just an added bonus; isn't the point of the stake to provide another earth?

My understanding is that if I just earthed the ladder (to the house wiring) that's not enough. Need to understand if the opposite is true (connect to ground stake only)?

Alternatively, I've looked into the sacrificial anode option. That also seems to have some very varying opinions on whether it works or not... seems the basic "put a zinc disk in the skimmer" option MAY work but the electric pipework based sacrificial anode is "better" - anyone have any real world experience of using this specifically to stop stainless steel rusting in a SWG based set up?

Oh, someone also mentioned chemistry levels: apparently SWG can make it tricky to keep PH and alkalinity down. I'm (just) about keeping on top of that; they said calcium can make this problem worse: my "hardness" looks ok though.

Many thanks
Ross

pool.jpg
 
mister_rossi_x said:
Hi all

I have an above ground pool - 4m x 2m, wooden frame with metal braces. Covered by a polycarbonate polytunnel - i.e. rain and leaves kept out.

An electrician fitted outdoor sockets back to an RCD for the devices that are plug & play (filter pump, SWG) and hardwired the heat pump and the Aquajet (counter current system for swimming).

My problem is that my stainless steel (marine grade) has rusted. I'm being told (supplier/manufactures) that this is a combination of the SWG and a "stray voltage" and that I should do the following:

Earth the ladders at the very least
Earth the ladders and any other electrical equipment that’s within the plant room to a copper ground stake
+
"It’s no good connecting to the house earthing ring unless its in conjunction with a ground stake"

or

Consider fitting a sacrificial anode.

I've done some research and it seems there's a general recommendation (although it's debatable whether it's needed for an above ground pool) to BOND the pool too.

This hasn't been done and I'm not 100% sure it's necessary for an AGP / my scenario, nor how it relates to the above recommendations?!

So my question is: what do I do to resolve the rusting ladder situation, given:

Outdoor pools in the UK are a rarity and no local electrician seems to have a clue about any of these subjects
There are no local pool experts
Pool experts are extremely expensive here
I'm very low on funds!!

I believe I could source a "copper ground stake" myself and install in the ground, and connect the ladder to this.
Does that DO anything, or do I also need to connect to the "house earthing ring"?

The equipment in the plant room are surely already earthed - both the hard wired and plug and play; the UK uses a 3-pin system with an earth. But do I need to connect this copper stake to the earth (in which case I need an electrician) or is that just an added bonus; isn't the point of the stake to provide another earth?

My understanding is that if I just earthed the ladder (to the house wiring) that's not enough. Need to understand if the opposite is true (connect to ground stake only)?

Alternatively, I've looked into the sacrificial anode option. That also seems to have some very varying opinions on whether it works or not... seems the basic "put a zinc disk in the skimmer" option MAY work but the electric pipework based sacrificial anode is "better" - anyone have any real world experience of using this specifically to stop stainless steel rusting in a SWG based set up?

Oh, someone also mentioned chemistry levels: apparently SWG can make it tricky to keep PH and alkalinity down. I'm (just) about keeping on top of that; they said calcium can make this problem worse: my "hardness" looks ok though.

Many thanks
Ross

View attachment 619639
Click to expand...
What model salt water chlorine generator or what is the salt level? Swimming pool systems are way less salinity than ocean water so it’s unlikely to be caused by a little salt in the water.

Not sure I can help on the electrical part except to say the anodes won’t do much and that if you can measure any voltage between the water and surrounding items like ladders, anchors etc, that those would be the path to start searching for. Ideally there’s no voltage across the water to anything else.
 
mister_rossi_x said:
Hi - it's the Bestway Flowclear Hydrogenic 6g/h Saltwater Chlorinator. Can't recall salt amount off the top of my head but it's added as per the manual's recommendation and the unit glows green to say it's happy!
Click to expand...
How are you testing the salt level? The machine can’t measure it very accurately and can sometimes be quite off especially if it’s old. Sounds like yours is newish though. I’d ignore anyone saying salt is the issue unless you’ve got actual 35000ppm ocean salt water instead of 3000ppm pool water.
 
Hi - I've not tested. However, it's not going to be too high - if anything, it will be a little low, as my pool does leak a little / loose some water and I have to top it up. However, it hasn't got so low that it's affected the SWGs ability to produce chlorine; the chlorine levels are good.

I.e. it should have "about" the right amount of salt.

People aren't saying it's the salt causing it, they are saying it's the SWG and possibly a "stray voltage", whatever that is. Salt wouldn't rust a marine grade stainless steel ladder even if it was very high.
 
The solution for stray voltage is two fold - identify the source (remove it if possible)
& employ equipotential bonding.
This is different than grounding.
In the united states you should only have one ground rod per electrical service.

www.troublefreepool.com

Bonding vs Grounding

Electricity and water don't mix. Learn a few basic tips how to keep your family safe when dealing with electricity around your pool.
www.troublefreepool.com www.troublefreepool.com

Electrical Bonding - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
Thanks both. Note that my pool water is often just under 4ft; it's only if I over fill it when topping up does it go a little over. Hence the uncertainly over whether it needs bonding or not, but it sounds like it would be a good idea to do so. I've read through the attached and it sounds simple enough to do; although, what exactly does it connect to on any pool equipment? Any exposed metal part?

In terms of measuring the stray voltage - is this simply a case of putting a multi meter in the pool?? I've just tried and looks like I've got about 0.17V. I had this with the SWG running and not running (but still powered on in both cases). I also turned on the counter current system; no change in voltage.

Do I need to power off the SWG /filter pump / heater and see if powering off one of those stops the voltage in the pool?
 
All your equipment should also be gfci protected for safety.

Many plug & play equipment options have a built in gfci on the cord & do not have a bonding lug as they are double insulated.

You can still bond your water in this case.

I suspect your rusting may be due to your water chemistry.
You need a proper test kit and to follow the recommended
FC/CYA Levels
& What Are My Ideal Pool Levels?

In Indoor pools you want to have 30 ppm worth of cya. Not for sun protection but for buffering the fc.
Without it the fc can be harsh on people and equipment which can cause rust.
Low ph can also cause corrosion of metal parts.

The place to start is with accurate test results
Fc
Cc
Ph
Ta
Ch
Cya
Salt
Temp
 
Thanks; note I'm in UK - had to google GFCI:

"In the UK and in Europe when English is used it is called an RCD (residual current device). In the US it is called a GFCI."

Everything is wired up via RCD/GFCI.

I'll double check the CYA level but think it's within range.
 

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mister_rossi_x said:
Thanks both. Note that my pool water is often just under 4ft; it's only if I over fill it when topping up does it go a little over. Hence the uncertainly over whether it needs bonding or not, but it sounds like it would be a good idea to do so. I've read through the attached and it sounds simple enough to do; although, what exactly does it connect to on any pool equipment? Any exposed metal part?
Click to expand...
You would encompass the pool with a continuous copper wire and bond the pool wall at 4 equal points (if its metal) to this ,
then the water itself (there are inserts that can added to your plumbing or skimmer), possibly the ladder,
And any equipment that has a bonding lug. (Different than the equipment ground)
Show us pics of your pool wall, the ladder and each piece of equipment.
mister_rossi_x said:
In terms of measuring the stray voltage - is this simply a case of putting a multi meter in the pool?? I've just tried and looks like I've got about 0.17V. I had this with the SWG running and not running (but still powered on in both cases). I also turned on the counter current system; no change in voltage.

Do I need to power off the SWG /filter pump / heater and see if powering off one of those stops the voltage in the pool?
Click to expand...
Yes
 
I've added some photos as requested. I need to check if any of my equipment has bonding lugs.

I'm struggling to isolate the cause of the stray voltage, as my multi meter is playing up - sometimes it gives no readings and you have to reset it. I've got a small battery with me so I can check it's working at any given moment, but the stray voltage doesn't always show. Sometimes it's only 0.04V, others in the 0.17 - 0.21V range. Other times it's showing only 0 or 0.01V. However, I haven't managed to get it to read above 0.01V with the SWG off after multiple attempts, so I'm thinking that's the cause.

Shouldn't a SWG introduce a small charge anyway, as part of the process of how it works??

I've realised I don't have any test strips left that measure CYA so need to buy some more.
 
Last edited:
I suggest you accept the rusting ladder as a consumable and plan to replace it every few years.

You are unlikely to fully resolve your stray electrical situation.
 
ajw22 said:
I suggest you accept the rusting ladder as a consumable and plan to replace it every few years.

You are unlikely to fully resolve your stray electrical situation.
Click to expand...
Well, my family motto translates as something like "we will not be defeated" - sooo... I'm gonna at least have a go trying to fix this!!

Also, it's rusted a lot, very quickly (2 months) - and it's leaving debris in the pool - so I want to at least minimise the rusting / slow it down if possible.

Also, the ladder came with the pool and is designed to fit it onto one of the long sides - due to my enclosure, I could only fit at the short side, and I had to do some heavy modification / wood drilling that was blimmin' difficult and time consuming, so that's another reason I'd like to keep this ladder!

Anyone any experience please with a similar situation and going down the sacrificial anode route??
 
mister_rossi_x said:
Well, my family motto translates as something like "we will not be defeated" - sooo... I'm gonna at least have a go trying to fix this!!

Also, it's rusted a lot, very quickly (2 months) - and it's leaving debris in the pool - so I want to at least minimise the rusting / slow it down if possible.

Also, the ladder came with the pool and is designed to fit it onto one of the long sides - due to my enclosure, I could only fit at the short side, and I had to do some heavy modification / wood drilling that was blimmin' difficult and time consuming, so that's another reason I'd like to keep this ladder!

Anyone any experience please with a similar situation and going down the sacrificial anode route??
Click to expand...
0.4V is quite a lot. Is this just a wooden frame with a liner? If so, it would seem you could bond the water and the ladder together to the bonding lug on the equipment.

A ladder rusting that fast is pretty unusual. I’ve got a stainless ladder in mine for 5 year now with a SWCG. and no sign of rust. It had been in the water for 20 years prior without a SWCG.
 
mister_rossi_x said:
Sorry, typo - have corrected - I meant 0.04V! The highest I've seen it was 0.21V.

It's a wooden frame and liner, but there are 4 metal braces too.
Click to expand...
That’s good. Though 0.21V is kinda high. If it’s only high when equipment is on then that’s something to look at fixing.
 

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