Discuss Supply to summer house TT system in the Electrical Forum area at ElectriciansForums.net

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Hi all , this is my first post , i’m a qualified electrician but I spend my whole time sub contracting to a factory installing and moving machinery so i’m a bit out of touch ( although taking the 18th on may 3rd ) with domestic work! A friend has asked for a supply to his summer house so I took a quick look and ordered the bits , I’d like to point out there was a lot of clutter around the mains area ! It turns out it’s a tt system i’ve installed a lewden 63a switched fused with 10mm 3 core swa 30 metre run to a lewden garage unit 32a ring and 6a lts, the system isn’t running yet but I’m thinking i’m gonna have to install an s type rcd at the house end and an earth stake at the summer house, I haven’t taken a ze yet , i’m trying to get a definitive answer from the regs but other people’s view would be appreciated! Cheers Russ
 
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telectrix

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sounds like a plan there.delay RCD house end additional rod/s at summer house. 30mA RCD in summer house (as main switch?)
 
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Yeah , the garage unit has an rcd main switch so that’s sorted , I can’t believe what a pain in the arse a tt system is , I used to work for SSE and when you talk to the older lads they always said a TT system was the safest but the protection required makes you wonder!
 
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I’ve only put 16mm tails in but I figure any fault would take out the rcd before getting back to the cutout !
 

telectrix

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no way is TT the safest. fault currents are generally far too low to take out a fuse, this is why we need to fit RCDs for fault protection. a nice sub 0.3 ohms on a TN-S is my fac=vourite choice. TNC-S is good till you lose N on the DNO sullpy.
 

suffolkspark

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Literally all you need to do is wop the main switch out of the switch fuse and stick the type S in there and your good to go, good practice to have used a gland to secure the tails into that too
 
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Just had a thought , i’m gonna take the Rcd from the garage unit in the shed and put it in the fused isolater and have the main switch in the shed job done ! Also gonna swap the tails for 25mm as thats a note on a periodic!
 
You can only swap components if they are compatible with the enclosure. Don't go making ad hoc replacements it will not be compliant to the Regulations.
 
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No both units are both brand new metal clad , lewden units , believe me I won’t be taking any short cuts !
 
D

Deleted member 9648

You don't need an additional rod at the summer house end, it is compliant to use the rod at the supply end. However an additional rod will bring down the Ra and provide a more reliable earthing system. It's common for electrode connections to come adrift or be cut. Less chance of that with two.
 
You don't need an additional rod at the summer house end, it is compliant to use the rod at the supply end. However an additional rod will bring down the Ra and provide a more reliable earthing system. It's common for electrode connections to come adrift or be cut. Less chance of that with two.
Installing a rod at the remote end improves the overall effectiveness of the earth nest as you have a wider contiguous connected area.
 

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