Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 20 replies
  • Subscribers 38 subscribers
  • Views 2344 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Which is safer/safest pump style in a garden 'splasher style' swimming pool?

GaryD

I'm really struggling to opt for the safer option on pump. This has come up because instructions on the pumps supplied state "do not use while in the water", but, as was inevitable eventually, someone forgot and swam without switching it off once....

I was provided with a 240v pump, externally mounted, but instructions state "do not use while in water". This design pump blew up (2x) - likely overheating as it was the resin seal that failed both times.

I bought a different one (designed for pools still), but this I discovered on arrival is submerged within a sump in the filter - it hasn't over heated - water cooled, but again "do not use while in water" label attached.

So... I know a little bit about electricity, but not a lot. So I figured that I could purchase a 24V DC pump, externally mount it, and this would be powered by an SELV transformer. The pump is 100W.

Would this DC pump running with the SELV transformer be safer?

I'm concerned because SELV means that there will not be anything  that causes the electricity to cut out if there is a fault on the DC side.

The RCD and AC 240v option however, has an earth at the motor, so theoretically, a failure will cause an earth fault and trip the RCD, but, if for some design reason, the earth isn't affected by the mechanical fault and water gets to the live, the pool is then electrified to 240v and then RCD does not trip. Typically, this is accounted for by bonding the pool water to the earth, though it's not as I understand it so trivial, since if you do that, you expose the water to potential fluctuations in the earth voltage (TNCS supply). To avoid that, you'd then convert the supply to TT setup.

In short, my understanding is that there is a risk that without bonding the pool water, especially with a submerged pump, there is a risk of electrocution even with a modern RCD fitted, regardless of type.

Hopefully you can see my confusion, and knowing a bit more than me, be able to put my mind at ease as to the safest option. Ideally without converting the supply to TT and installing earth bonding for the (temporary!) pool water.

What would you install if you owned a splasher style temporary pool?

Parents
  • 0

    Worth also noting that:

    1. There is no voltage considered "safe" when someone is fully immersed in water.

    2. In Sections 701 and 702, BS 7671:2018+A2:2022 limits the types of electronic equipment that can be used as a source for SELV/PELV in certain zones.
  • 0 in reply to gkenyon

    Thank you for pointing me to that section. 702.410.3.4.1 does at the end state "The socket outlet of a circuit supplying such equipment and the control device of such equipment shall have a notice in order to warn the user that this equipment shall be used only when the swimming pool is not occupied by persons".... which is great (and effectively explains why all the pump manuals state "this product must not be used while water is occupied", but public swimming baths / water splash parks etc have pumps running while occupied, so there must be more to it than what is contained with the "requirements for electrical installation". Is there a separate british standard used for commercial pools / water parks (fountains in an enclosed space children run around in and under)?

    Many thanks.

  • 0 in reply to GaryD

    I think that a commercial pump in a public swimming pool will be an entirely different beast to that which you'd be prepared to have on your domestic setup.

    For example, it would probably live in a plantroom, it could be a mechanical pump driven my a separate electric motor. If the mechanical coupling of the two is made of an insulating material & they are mounted on a non-conductive bed it would be pretty much impossible for a fault in the motor to transfer to the water. 

  • 0 in reply to AdrianWint

    I wired a couple of pumps for a public swimming pool, not that many years ago.

    The pumps were standard types close coupled to induction motors, as would be used for chilled water or wet central heating in large buildings.

    The pumps were some distance away from the pool, and the pipes were plastic, presumably the length of plastic pipe was considered a sufficient precaution.

    I did not design the installation, but was simply connecting pumps installed by others. Two duty/standby pairs of pumps. One pair for a waterfall and the other pair for a waterslide. 

    The heat from two large air conditioning chillers was rejected into the swimming pool thereby warming the water. This worked well except in heatwave conditions when the pool became too warm. I suggested that in such conditions that the waterfall pumps be run at night in order to cool the water.

  • 0 in reply to gkenyon

    I accept your point about no voltage being safe - having scared myself with the sparks from a car battery and indeed electric fences, the idea even of attaching electrodes from 12v let alone a 24v power running through the water and certainly much less 240v doesn't thrill me - which means I'm nervous where this might be done for me at some random point by an electical fault.

Reply
  • 0 in reply to gkenyon

    I accept your point about no voltage being safe - having scared myself with the sparks from a car battery and indeed electric fences, the idea even of attaching electrodes from 12v let alone a 24v power running through the water and certainly much less 240v doesn't thrill me - which means I'm nervous where this might be done for me at some random point by an electical fault.

Children
No Data

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines