UK Is my UK bought pool pump configuration safe? Should I change it?

[Gareth D]

Hi,

I hope that someone here might be able to put my mind at rest. I have an engineering mind and a reasonable understanding of electical work, but I'm not confident on this area and want to ensure the safety of my family.

I purchased a bestway splasher pool a few years ago (holds around 10000Litres of water). It came with a 240v externally sited circulation pump that is NOT submerged. This failed very quickly due to overheating and was replaced with another - same issue, so when it was replaced, I opted not to use it but bought a different branded pump (from intex). This pump is also 240v and externally siutated, however, it is submerged in the pool water as it sits inside the filter assembly, rather than just the impellor being in the water. Now, I am guessing that this is great for cooling since the pump is unlikely to overheat in the 14 - 24c water jacket. However, when the bestway pumps failed, they both failed by getting too hot and the epoxy seal on the pump cracking allowing moisture ingress.
If this were to occur on the intex pump, it would one presumes electrify the pool water to 240v until the RCD kicks in (we've a new consumer unit with a 30mA 80A RCCB covering this and other circuits).

Usually, I ensure it is always switched off at the mains before entering the pool, however, last night, my wife and son used the pool and forgot - so if it had of failed as described, I wonder if it was unsafe. My gut instinct says that it is unsafe however statistically unlikely (I think more than immediately apparent since the quality of the pump motors is likely cheap and cheerful if anything like my experience with the bestway ones).

As a result, I am considering a 24v DC external mounted "amphibious" (i.e. not sitting in water and designed as such) style pond pump. This will be plugged into the mains still, but, if I'm correct, being attached to a 24v transformer, it will result in substantially smaller risk of reduced life expectancy should it fail when someone is in the pool - thus allowing us to leave it switched on and e.g. run a waterfall effect while in the pool.

N.b. you might say "why not use a pool specified and designed pump" but the reality is that pool pumps are all large, high powered and consquently both expensive to both buy and run.

Both existing 240v and the 24v pump I'm considering are 45w. Hopefully this gives you an idea of the installation scale I'm talking.

So to recap, my questions are:
1. Should I be paranoid about the safety of the existing intex pool pump when someone is in the pool and it is running.
2. Can I sleep easy if I go down the route of a 24v DC transformer powered pump?

Many thanks for your time and consideration of the above. I've read and re-read the "requirements for electrical installation" manual that electricians learn to qualify, but I've not found the information needed to make a confident decision.

 

[Avo Mk8]

I hope the better informed will be along in a bit, but meanwhile, to give simplistic answers your questions:
1) If your pump is the Intex 633 model, I see the instructions say, in bold: "Do not operate this product when pool is occupied".
2) For your 'pond pump' project, you need to ensure any transformer you use is designed for safe isolation in your sort of application. I would suggest you need a product with a SELV transformer, see Separated Extra Low Voltage (SELV) - https://www.meanwelldirect.co.uk/glossary/what-is-separated-extra-low-voltage-selv/

With safety comes a degree of cost, and the electricity/swimming pool combination is a good example. Personally I would be looking for a solution that is designed to be safe and run while people are in the pool, not relying on "remembering" to turn it off.

 

[Mike Johnson]

Have a look at Koi Carp pool pumps, designed to run for 24hrs at a much reduced power consumption, just ensure you get at least two changes of water volume in a twenty four hour period to keep the water disinfected.

 

[Gareth D]

I hope the better informed will be along in a bit, but meanwhile, to give simplistic answers your questions:
1) If your pump is the Intex 633 model, I see the instructions say, in bold: "Do not operate this product when pool is occupied".
2) For your 'pond pump' project, you need to ensure any transformer you use is designed for safe isolation in your sort of application. I would suggest you need a product with a SELV transformer, see Separated Extra Low Voltage (SELV) - https://www.meanwelldirect.co.uk/glossary/what-is-separated-extra-low-voltage-selv/

With safety comes a degree of cost, and the electricity/swimming pool combination is a good example. Personally I would be looking for a solution that is designed to be safe and run while people are in the pool, not relying on "remembering" to turn it off.

Thank you Avo Mk8.

I agree that the intex pump (604 Model) itself says "don't use while people are in the pool". Their website states in the FAQ that their pumps are EN etc safety rated, but for local specific reasons (no idea what that would be), they have to state that you shouldn't be in the pool at the same time. Purportedly an RCD should protect against electrocution, so, having two in series would seem a fair mitigation, but presumably these aren't deemed bulletproof since current needs to leak to the earth terminal to trip them and if the water were to connect with the live wire first by a second or so.....

Larger pool pumps are externally mounted, and run from 240v, so it must be that it is possible for them to be deemed safe. When the pumps are externally mounted, and have a magnetic driven impeller (vs direct shaft drive), the electrics are totally isolated so theoretically there can not be an issue if the pump i configured like this regardless of size.

I've searched a fair bit online, discovered there are 24v pumps that match my requirements, though they are mainly incorrectly understating their power draw (found the source manufacturer and checked their specifications). I was initially hoping of buying a separate high current static voltage LED driver, but for the current draw actually stated at 24v, this isn't really cost effective. Not to mention that the pumps seem less efficient than the AC ones (then there's the efficiency of the transformer and rectifier too to consider).

I'm pondering a pond air pump at the moment to utilise creating an air lift pump combining with a gravity filter.

 

[Gareth D]

I hope the better informed will be along in a bit, but meanwhile, to give simplistic answers your questions:
1) If your pump is the Intex 633 model, I see the instructions say, in bold: "Do not operate this product when pool is occupied".
2) For your 'pond pump' project, you need to ensure any transformer you use is designed for safe isolation in your sort of application. I would suggest you need a product with a SELV transformer, see Separated Extra Low Voltage (SELV) - https://www.meanwelldirect.co.uk/glossary/what-is-separated-extra-low-voltage-selv/

With safety comes a degree of cost, and the electricity/swimming pool combination is a good example. Personally I would be looking for a solution that is designed to be safe and run while people are in the pool, not relying on "remembering" to turn it off.

Thank you Avo Mk8.

I agree that the intex pump (604 Model) itself says "don't use while people are in the pool". Their website states in the FAQ that their pumps are EN etc safety rated, but for local specific reasons (no idea what that would be), they have to state that you shouldn't be in the pool at the same time. Purportedly an RCD should protect against electrocution, so, having two in series would seem a fair mitigation, but presumably these aren't deemed bulletproof since current needs to leak to the earth terminal to trip them and if the water were to connect with the live wire first by a second or so.....

Larger pool pumps are externally mounted, and run from 240v, so it must be that it is possible for them to be deemed safe. When the pumps are externally mounted, and have a magnetic driven impeller (vs direct shaft drive), the electrics are totally isolated so theoretically there can not be an issue if the pump i configured like this regardless of size.

I've searched a fair bit online, discovered there are 24v pumps that match my requirements, though they are mainly incorrectly understating their power draw (found the source manufacturer and checked their specifications). I was initially hoping of buying a separate high current static voltage LED driver, but for the current draw actually stated at 24v, this isn't really cost effective. Not to mention that the pumps seem less efficient than the AC ones (then there's the efficiency of the transformer and rectifier too to consider).

You are indeed correct - it seems impossible to solve the problem in a bomb proof safe manner for a cost appropriate with the total cost of the pool. The whole pool and filter pump etc kit came to about £400, so the idea of spending a small fortune on the pump extra feels galling. Imagine buying a car, discovering something as fundamental as the engine was inadequate (think first generation VW camper vans), then having to buy a bigger one to make the car work as designed....only then it eats more fuel than budgeted for and was the reason purchased in the first place. Maybe there are better analogies, but RAH!

 

[Gareth D]

Have a look at Koi Carp pool pumps, designed to run for 24hrs at a much reduced power consumption, just ensure you get at least two changes of water volume in a twenty four hour period to keep the water disinfected.

Thank you Mike. My father in law pushed me towards the Koi pond equipment some time ago and I've resisted over the cost of it. I am not carefully hunting through. My existing pump uses (apparently as its written on the side) 45W, and it achieves a measured throughput of circa 1500LpH with filters etc fitted at a minimal head. Connections are all 32mm. I have borrowed an old 300W pool pump from a neighbor and this had a vastly superior head (experimented how high I could make a fountain with it) and flow rate - but, and it's just my opinion but it seemed so powerful it was literally blasting all the fine particles straight through the filters (I could see a cloud entering the pool again). I'm considering a gravity based filtration system now having seen this.

I think I'm beginning to see the purpose of the circulation too - its less about the filter and more about moving the chlorine around so that the algae cannot use it all up in one small area, then start growing and thus get a toe then foot hold....

 

[Mike Johnson]

Slowing down the pump and keeping it on longer saves a considerable amount of power, I used a VFD (variable Frequency Drive) overall savings over a year was 750EU with savings made on not buying chemicals from the pool store, I did write an article on this, but can't seem to find it at the moment, will have a search.

 

[Gareth D]

Slowing down the pump and keeping it on longer saves a considerable amount of power, I used a VFD (variable Frequency Drive) overall savings over a year was 750EU with savings made on not buying chemicals from the pool store, I did write an article on this, but can't seem to find it at the moment, will have a search.

Thanks for your response Mike. I'd be interested to read the article you refer to if you locate it In my case, if I opt for a DC motor, that will permit variable speed control, so hopefully I can achieve something similar.

 

[Mike Johnson]

Thanks for your response Mike. I'd be interested to read the article you refer to if you locate it In my case, if I opt for a DC motor, that will permit variable speed control, so hopefully I can achieve something similar.

Gareth D managed to locate the article, its eight A4 pages so too big for a post, PM me your e-mail address and I will send it to you.

 

[Gareth D]

Presuming I replace the existing pump with a 24V DC pump (not yet purchased) to be external (not submerged), will that alleviate the risk of electrocution entirely without getting the pool water bonded and the shed MCB configuration (modern with RCBOs and MCBs) switched to being a standalone TT system with an earth rod etc? My understanding is it is the fact the water is not bonded to the electrical earth that means there is a way the water could end up being 240v yet the RCBO not trip (ignoring electrical potential difference possibility due to connection to the PME), but presumably with a low voltage device, the possibility still though much more remote (with a magnetic drive in the pump, there would have to be some catastrophic pump failure) exists of the water being charged to the voltage of the low voltage device in use (in this case 24V) and there is no issue with regards the earth wire not necessarily being 0v since no connection exists past the transformer. Our house is currently TN-C-S. I should stress again, this is a temporary 10'000L splasher pool - electrical system alterations feel overkill (presumably the temporary pool sellers agree otherwise they'd be anxious about being sued for death by electrocution).

 

[mainline]

Presuming I replace the existing pump with a 24V DC pump (not yet purchased) to be external (not submerged), will that alleviate the risk of electrocution entirely without getting the pool water bonded and the shed MCB configuration (modern with RCBOs and MCBs) switched to being a standalone TT system with an earth rod etc? My understanding is it is the fact the water is not bonded to the electrical earth that means there is a way the water could end up being 240v yet the RCBO not trip (ignoring electrical potential difference possibility due to connection to the PME), but presumably with a low voltage device, the possibility still though much more remote (with a magnetic drive in the pump, there would have to be some catastrophic pump failure) exists of the water being charged to the voltage of the low voltage device in use (in this case 24V) and there is no issue with regards the earth wire not necessarily being 0v since no connection exists past the transformer. Our house is currently TN-C-S. I should stress again, this is a temporary 10'000L splasher pool - electrical system alterations feel overkill (presumably the temporary pool sellers agree otherwise they'd be anxious about being sued for death by electrocution).

Even if you used a 240v pump, as long as it's remote from the pool and no metal pipe work, it will be fine.

 

[Gareth D]

Even if you used a 240v pump, as long as it's remote from the pool and no metal pipe work, it will be fine.

Thank you for getting back to me.
My current solution is a 35w air pump that runs a few home made bubble pumps. This shifts well in excess of the volume of water that was being shifted using the old 45w centrifugal pump for less power and complete electrical isolation. It's still experimental really, but it seems to work very well so far.

 

[Mike Johnson]

230volt technology is well established as a pool pump in most countries around the world, I think you are worrying about something that would be such a rare occurrence it will probably never happen, don't complicate things unnecessarily, life is too short, go swimming its good exercise and very therapeutic with a G&T.

 

[Mike Johnson]

Gareth D managed to locate the article, its eight A4 pages so too big for a post, PM me your e-mail address and I will send it to you.

If anyone else is interested in this pool expense saving article, PM me and I will send it, unless the mods can find a way to post an eight page A4 document, I think it would be of interest to a lot of people.

The document has a fair few tables in it so converting to a PDF is not possible without loosing the pagination and making a nonsense of the content.