Hot tub electric shock

[Samhhh]

Hi I'm looking for some advice, yesterday when exiting my hot tub I felt a slight electric shock when my foot made contact with the ground around the hot tub. I work as a cable jointer so a tingle is second nature to me so I double checked when in contact with ground and water I can feel a slight tingle in my fingers when isolated from ground I feel nothing. Today I put my multimeter onto a nearby earth terminal and probed the water to get a reading of 0.2volts. Im on a pme supply and have a cable running from a rcd to a isolated and then a feed to the tub. Any idea where this voltage could be coming from? And if installing a seperate earthing point with rods would solve the issue? Thankyou

 

[Samhhh]

I don't see why you needed to pull the main fuse.

I'm a cable jointer so it's just easier for me to deal with what I know ?

 

[timhoward]

He's said one way to prove it completely would be to turn off and open up the rotary isolator and remove the earth connection then test again if the voltage has gone then its potential difference as the tub Is no longer grounded itself, if the tub still has volts it could be that a component of the hot tub is leaking voltage into the water and not potential difference?

Wouldn't do that.
You are then running the hot tub with no earth, which is considerably more dangerous than the tingle you are trying to identify!

 

[LastManOnline]

Could this voltage increase and be dangerous or will it always stay the same dependant on conditions.

Try using your hot tub in "off peak" hours and see if you feel that "tingle". If you don't then as the other posters have already stated the sensation is very likely caused by the voltage difference between your PME earth and natural earth. This volt drop is normal and goes up and down depending on the current flowing in the DNO, s supply system.

 

[buzzlightyear]

Reading this post me thinks there is a fault on the hot tub.
Has pc 99 says it could be 12 volts from the lighting in side the tub, any higher he could be fried Chris. And dried.

 

[Samhhh]

Reading this post me thinks there is a fault on the hot tub.
Has pc 99 says it could be 12 volts from the lighting in side the tub, any higher he could be fried Chris. And dried.

But wouldn't this voltage go once the power is removed from the tub?

 

[LastManOnline]

But wouldn't this voltage go once the power is removed from the tub?

Correct. Once power is removed you should no longer feel any voltage. Is your rcd double or single pole?

 

[Samhhh]

Correct. Once power is removed you should no longer feel any voltage. Is your rcd double or single pole?

Double pole mate

 

[LastManOnline]

Double pole mate

Based on that then it can only be the supply earth that's causing the issue. I agree with your brother. Disconnect the supply earth and see if "tingle" disappears.That will confirm it.

 

[Samhhh]

Based on that then it can only be the supply earth that's causing the issue. I agree with your brother. Disconnect the supply earth and see if "tingle" disappears.That will confirm it.

I think for this one I will just stick with the multimeter results rather than doing the finger test ? thankyou for the help is much appreciated

 

[brianmoooore]

I would never install a hot tub on TNC-S. My own are on a genuine TNS system, and use the DNO earth, but if it were TNC-S, the tubs, and the buildings by them, would be TT.

 

[pc1966]

I would never install a hot tub on TNC-S. My own are on a genuine TNS system, and use the DNO earth, but if it were TNC-S, the tubs, and the buildings by them, would be TT.

More and more I am thinking all hot tubs should be on a TT supply, as even if your supply appears to be TN-S there is a chance that elsewhere repairs or cable replacement has essentially converted your supply to TN-C-S (just a rather long 'S' there).

 

[LastManOnline]

I would never install a hot tub on TNC-S. My own are on a genuine TNS system,

And now we come to the nub of the problem. An unsatisfactory supply system. TNS was and is the only proper supply system. Ironically I thought that a combination of outside metalwork like heat pumps, electric gates, electric vehicles etc would highlight the frailties of TNC-S. But I now wonder if it may be hot tubs that eventually highlight the issues!!

 

[brianmoooore]

By "genuine TNS" I mean that I can see all the earthing rods, and every inch of the supply cables, all the way from the 11kV - 230-0-230 Tx, to all three DNO service heads

 

[pc1966]

By "genuine TNS" I mean that I can see all the earthing rods, and every inch of the supply cables, all the way from the 11kV - 230-0-230 Tx, to all three DNO service heads

You are very lucky then!

 

[LastManOnline]

By "genuine TNS" I mean that I can see all the earthing rods, and every inch of the supply cables, all the way from the 11kV - 230-0-230 Tx, to all three DNO service heads

Then as pc1966 states you have truly a unique situation. Can I enquire about the earth rods? TNS is the one supply's system I have never worked on. What is the earth electrode arrangement?