swimming pools

[jj2785]

hi all new here,
i was having an early morning swim at my local DW sports gym and notice the cleaner walking round the side of the pool with some sort of tile cleaner pluged into a normal coil extension lead, is this ok? i know theres a lot of moden electrical safety things these days but i still got out the pool thinking of if she knocked it in the water!

 

[Chri5]

It isn't a problem

 

[ricicle]

I would question the use of such an item in the pool area when it is in use. Some appliances (such as underwater pool cleaners) are obviously designed to work in the wet but not when the pool in in use. I would be wary of this item unless the manufacturers instructions specifically say it can be used when the pool is in use.
If you are overly concerned speak to the pool manager.

 

[stillp]

I agree with the cautionary approach, but, slightly tongue-in-cheek, I wonder what would have happened if she had dropped it in the water? Would there really be a risk of electric shock to someone in the water?

 

[mikhailfaradayski]

probably not (assuming power is via an RCD) but i wont be in a rush to get my speedos on to go and prove it

 

[stillp]

Mikhail, I was thinking more along the lines of what the current path would be, rather than the operation of an RCD.

 

[bernardgreen]

Mikhail, I was thinking more along the lines of what the current path would be, rather than the operation of an RCD.

The chance of a serious electric shock does depend on the paths the current from live takes to reach neutral and or earth. There will be a voltage gradient ( volts per metre ) along thsese paths and to get a noticable shock the person must be in an area where the voltage gradient is high enough that different parts of the body are in water at different potentials.

If the cleaner has an earthed casing then then the majority of current flow in the water will be contained in the machine. If it is double insulated and no earth then it presents a greater hazard to swimmers as the live to earth current flow might be the full length of the pool if the earth ( pipe work etc ) is at the end furthest from the machine.

 

[securespark]

probably not (assuming power is via an RCD) but i wont be in a rush to get my speedos on to go and prove it

That doesn't sound like the mik of old.

I was rather hoping you'd have posted a video of you testing this theory by now...

 

[bernardgreen]

but i wont be in a rush to get my speedos on to go and prove it

Aren't speedo's made of insulating material ? The results would not be valid for a man in boxer shorts or a lass in a bikini.

 

[mikhailfaradayski]

probably not (assuming power is via an RCD) but i wont be in a rush to get my speedos on to go and prove it

That doesn't sound like the mik of old.

I was rather hoping you'd have posted a video of you testing this theory by now...

ooh, you smooth talker. No matter how much you try to butter me up (ooh-err matron) ill not be posting vids of me wearing budgie-smugglers







well, not here, anyway

 

[mikhailfaradayski]

Mikhail, I was thinking more along the lines of what the current path would be, rather than the operation of an RCD.

The chance of a serious electric shock does depend on the paths the current from live takes to reach neutral and or earth. There will be a voltage gradient ( volts per metre ) along thsese paths and to get a noticable shock the person must be in an area where the voltage gradient is high enough that different parts of the body are in water at different potentials.

If the cleaner has an earthed casing then then the majority of current flow in the water will be contained in the machine. If it is double insulated and no earth then it presents a greater hazard to swimmers as the live to earth current flow might be the full length of the pool if the earth ( pipe work etc ) is at the end furthest from the machine.

Also, lets not forget that if the cleaner did go in the water, it would take the supply neutral with it aswell, so another low resistance return path, in very close proximity to the submerged line conductor.
Not saying a shock to any pool occupants is impossible, but i think it would take a rather obscure set of circumstances for this to happen - maybe as the cleaner went in, it strained the supply flex and broke the earth and neutral conductor?

 

[stillp]

Also, lets not forget that if the cleaner did go in the water, it would take the supply neutral with it aswell, so another low resistance return path, in very close proximity to the submerged line conductor.
Not saying a shock to any pool occupants is impossible, but i think it would take a rather obscure set of circumstances for this to happen - maybe as the cleaner went in, it strained the supply flex and broke the earth and neutral conductor?

My thoughts exactly. Even then, would the fault current flow through the water to earth, or through the person? What's the resistivity of chlorinated water, compared to the resistivity of the human body?

[I know, I need to get out more!]

 

[mikhailfaradayski]

Im not sure about the resistivity of the chlorinated water, but im sure google would help you with that.

However, what may be more important is the relation of resistances between 1) the line and neutral at the machine, 2) the line and earth at the machine and 3) the resistance between line and some kind of earth potential (pool pump system maybe?) given an unknown distance and volume of water.