13amp hot tub

[Funkyfridays]

It's basically same as the inflateable hot tubs but with solid sides and better insulation

 

[bernardgreen]

Ask your electrician if he ( or she ) is happy to export the "Earth" from the house to be the "Earth" for the hot tub.

He ( or she ) may consider that a TT supply to the hot tub with a local "Earth" ( a ground rod close to the hot tub ) would be the better option for safe "Earthing" of the hot tub.

 

[Funkyfridays]

Ok, if the eli reading at the garage is ok wouldnt u think that providing an outdoor socket for the hottub using the same earth from the house would be sufficient?

 

[ban-all-sheds]

Why do you keep asking random strangers on an internet forum questions which only your electrician can answer?

 

[Funkyfridays]

I thought these random strangers were here to offer advice, I thought that was the idea of this site, I'm interested to know everyones opinion on this installation??

 

[bernardgreen]

PME "earths" are fine for earthing things inside the house. The house is then what is known as an equipotential zone. All things that are "earthed" inside the equipotential zone are at the same potential ( voltage ) so touching any two "earthed" objects in the house at the same time will not give you an electric shock. The extent of the equipotential zone is normally defined by the walls of the house.

A problem can arise when a person is touching an earthed object that is in the equipotential zone and at the same time is touching something outside the equipotential zone that is earthed by a connection to the real ground outside the house. A common "breach" of the zone boundary occurs when a person is standing on the ground outside the house and is touching a water tap on the outside of the house wall and the tap is connected by copper pipe (and bonding wire) to the PME "earth" inside the zone

For 99.9% of the time such a breach gives no noticable shock ( or tingle ) as the PME "earth" and the ground are at the same potential give or take a few volts.

It is when there is a fault in the local supply network and the PME "earth" is no longer at Ground potential that a serious risk of electric shock exists at any breach of the equipotential zone.

Exporting the PME "earth" to any object that can be touched while the person is standing on the ground creates a breach of the equipotential zone. If at the same time as the breach there is also a fault in the supply network affecting the PME "earth" then the risk of significant electric shock exists

 

[Funkyfridays]

Would earthing the socket with a spike overcome this as well as the earth from the house as I'm not sure I could entirely have a seperate tt earth as the house is only 5 Years old so the incoming mains cable is pme

 

[JohnW2]

Would earthing the socket with a spike overcome this as well as the earth from the house ...

Not really, since the impedance iof the TT earth rod would be far to high to make much difference to the sort of potentially dangerous 'PME fault' that concerns bernard.

... as I'm not sure I could entirely have a seperate tt earth as the house is only 5 Years old so the incoming mains cable is pme

That's would not be a problem/issue - you would simply keep the PME-derived earth (electrically) away from the hot tub, and use only the local TT rod for the tub.

Kind Regards, John

 

[bernardgreen]

I could entirely have a seperate tt earth as the house is only 5 Years old so the incoming mains cable is pme

If only the Live and Neutral are taken from the house to the location of the hot tub and the earth for the location of the hot tub is provided by a Ground rod at the location then the installation at the location of the hot tub is a TT installation,

 

[Funkyfridays]

But the neutral that would be taken from the house is connected to the earth via pme via the mains incoming so cant be seperated?

 

[bernardgreen]

A detailed explanation can be read HERE

The various "earths" and Grounds are connected via the mass of planet Earth but as can be seen in this diagram the person touching the hot tub cannot get a shock as the hot tub and
the ground he is standing on are at the same local ground potential due to the Ground Rod

 

[Funkyfridays]

That's cool thanks I'll get my electrician and see what he says, to me in effect the neutral is an earth if connected to a pme supply as they cannot be seperated

 

[ban-all-sheds]

Neutral is always an earth with the public supply in the UK, in the sense that it is earthed somewhere.

 

[JohnW2]

That's cool thanks I'll get my electrician and see what he says, to me in effect the neutral is an earth if connected to a pme supply as they cannot be seperated

All supply neutrals are connected to earth somewhere, even if only at the transformer in the substation - and with PME ('Protective MULTIPLE earthing') also at other places.

However, in the context we're discussing, it is not the neutral that we're interested in, since that is not something one cannot (should not be able to) touch. What we are interested in is how any exposed touchable metal has been 'earthed' - and that depends upon how things have been wired. If one connects that exposed metal to an earth derived from the supply neutral within the property, then one has a 'PME earth' (which invokes the issues that bernard mentioned). However, if the exposed metal is all connected (only) to a local TT earth rod, then there is no connection between that metal and the supply neutral.

Hope that helps!

Kind Regards, John

 

[Funkyfridays]

Awesome thanks for the information guys will be interesting to see what my electrician says, looking like the tt would be the safer option