Wiring a hot tub on a TT system

[devonsparky]

Just a quick one

I'm wiring up a hot tub tomorrow (yes, on a Sunday !) know I shouldn't transport a PME earth to the installation.
The house is out in the sticks and on a TT ................ my query is, would you still put an earth electrode locally to the hot tub or would you rely on the main earth ?

 

[Guest55]

well if its a TT supply you'll have no PME to export.
so fit earth rod local to hot tub.

 

[mayfair]

I cant quote for UK m8 but have done a few of these I always TT them. Not as deep as Eng 54 would like but thats life!

 

[MarkieSparkie]

We need a bit more information mate. Is the hot tub in the house or outside? What RCD protection? What's the quality of the existing TT earth.

 

[devonsparky]

Hot tub is outside ....... It is rated at 43.5A so I'm putting it on a 1 way board (Main SW 63A RCCB 30mA + 50A MCB) - 10mm SWA
Ze (TT) is 111ohms

Just curious to ideas on whether anyone would also earth electrode at the rotary isolator for the hot tub?

 

[Engineer54]

It is almost always better to link the earth electrodes on TT systems, ie ...the more rods on the system the better. This can be achieved by the SWA of your supply cable as a last resort, but better if you include a separate core in your cable to take back to the MET...

What is the hot tub sitting on, ...Grass, concrete or slab patio, Wooden decking?? If it's sitting on grass or concrete patio, then i would want to see a much better value than the existing 111 ohm Ra...

 

[i=p/u]

id earth from new mcb/rcbo enclosure....... would i have to pipe to my eaqrth rod is what i dont know, but i wouldnt do this job.. good luck

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i know mechanical protection from regs and all but just cant picture it and never installed an earth rod yet

 

[Engineer54]

id earth from new mcb/rcbo enclosure....... would i have to pipe to my eaqrth rod is what i dont know, but i wouldnt do this job.. good luck

i know mechanical protection from regs and all but just cant picture it and never installed an earth rod yet

Why would you Not give the earth cable mechanical protection, surely you wouldn't leave it underground without any protection, .....would you??

 

[i=p/u]

over certain size you dont need mechanical protectiosn

 

[Engineer54]

So because it says that in book, you would leave a TT protective conductor without any form of mechanical protection in a domestic garden environment?? Would you consider that a sound judgement??

 

[richy3333]

Mine always get mechanical protection. No amount of hazard tape can account for a numpty with a shovel and a desire to dig through to Australia!

 

[i=p/u]

so do you normally put in duct of what material??????? size?

 

[SPARTYKUS]

I've chopped through an SWA a few times with my spade. Thought it was a tough tree root.

What I'm saying is EVEN armoured cable isn't numpty proof. Especially one thats frothing at the mouth with a crazed look in his eye with a Steel spade

 

[keniff]

On my hot tub I had a small distribution actually inside the hot tub (manufactured like this) I took a earth spike to that board, and got it down to 13ohms, also I think your ok to supply with pme if you also get an earth rod with resistance bellow 22ohms locally

Also remember to take your swimming shorts to test it!