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Jc1996

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Hi guys I have a question on installing an outside supply to a spa at home. I have a few questions regarding this one is the consumer unit has no spare ways have checked maximum demand and all seems okay for an additional 32 amp load. My plan was to get a garage style CU and take out out of the 6 amp lighting circuit breakers at the main board and replace with a 40amp breaker to feed the new CU containing the lighting circuit and swim spa circuits. I’m then planning on running a 6mm swa outside to a rotary isolator. 
 

first question is does the new CU require surge protection? (I know this will have to be signed off by someone who is registered as I’m not registered)

Does the lighting circuit require an installation certificate as well? I’m presuming it will as I’m installing it in a new board. 
 

and lastly (I know there is many debates about this) but what are your guys thoughts on TNCS supplies and earth electrodes? I’ve been told by the manufacturer they’ve never heard of any electrician ask about using an earth electrode? 
 

thank you for your replies in advance 

 
Last edited by a moderator:
surge potection is not obligatory.

you will need to test and cert the lighting.

Garage CU is fine

Exporting earth on TNCS is not a good idea, strictly speaking it's illegal to export the earth outside of the equipotential zone wthout permission of the DNO - there's various pots about this subject on here if you search them out. What I would do is TT the spa building, the sub main needs to be earthed at the house end, but do not connect this earth in the spa building, use a rod that end. 

 
Surge protection is required at the supply point of entry to the building. So one DB feeding another would only need surge protection in the first one. If the tails were split into Henleys then I would have a separate surge protector to protect the installation.

 
surge potection is not obligatory.

you will need to test and cert the lighting.

Garage CU is fine

Exporting earth on TNCS is not a good idea, strictly speaking it's illegal to export the earth outside of the equipotential zone wthout permission of the DNO - there's various pots about this subject on here if you search them out. What I would do is TT the spa building, the sub main needs to be earthed at the house end, but do not connect this earth in the spa building, use a rod that end. 
Illegal??

 
looks more like he's refering to the location of SPD being at supply end / first DB vs remote DB futher away, not you jumping to conclusions accusing him of saying that SPD is always required...


His words are "is required"

which certainly reads as if SPD's are required to be fitted 

If @sidney had written "can be fitted" it would be a different matter

 
Thank you guys for your replies, the CU is an old plastic one so not to current regs was just not sure if this meant I’d need to fit one when carrying out my work as I know that the additions we carry out have to be up to the latest regs. 
 

Is standard practice to earth the supply cable at the cu and then separate the earth in the local isolator and have an earth rod connect to the isolator which is then the earth for the spa? 

 
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