mains change

[s18mcn]

Hello, ive just been to look at a job where the main fuse is in the middle of the kitchen due to an extension. The owner wants to tidy it up and move the fuseboard to other side of the doo, and the main head back outside. Would it be ok to run a 16mm t+e sub feed from the new metre position fe dvia a 63A breker to the new board with a seperate 10mm earth wire?
Also the board thats their is a split load one but due to the moving of it to its new position it has to be upgraded to 17th edition right?

 

[Spudnik]

Hello, ive just been to look at a job where the main fuse is in the middle of the kitchen due to an extension. The owner wants to tidy it up and move the fuseboard to other side of the doo, and the main head back outside. Would it be ok to run a 16mm t+e sub feed from the new metre position fe dvia a 63A breker to the new board with a seperate 10mm earth wire?
Also the board thats their is a split load one but due to the moving of it to its new position it has to be upgraded to 17th edition right?

You could use 16mm however, you may need to RCD protect it, which would then go against regs, depends on your chosen installation method.

No need to change CU, just use RCBO's where needed.

 

[SEC-Tom]

You could use 16mm however, you may need to RCD protect it, which would then go against regs, depends on your chosen installation method.

No need to change CU, just use RCBO's where needed.

Why would this be against regs? Discrimination?

 

[Spudnik]

............. Discrimination?

Yes as you would have 2 x 30mA in line.

 

[s18mcn]

could you not install a 300mA rcd? What would be the best way to get over this then?

 

[ajdeath]

This is very odd, I have just come on line to ask exactly the same questions with the same sinareo! I was going to take the 16mm t + E from garager to new board from a 60 a switch fuse but was also wondering about rcd as I wasn't sure about 2 in parrelel

 

[tuckermot]

use swa ( no rcd required ) to feed new ccu then fit your dual rcd board as normal .fitting two 30ma rcds in line is a big no no !!! discrimination will not take place!! depending on the sensitivity of the rcd ( if you was to use one ) protecting the feed to the new ccu this could trip could trip before the one in the new ccu causing you to loose all your circuits in the new ccu

Rich

 

[s18mcn]

Ive also seen a job where a 63A breaker has been installed next to metre then a 16mm t+e run to consumer unit. Is this also bad practice??

 

[Spudnik]

Chaps.

I know its hot but you need to have a little think

Will the submain need 30 mA RCD protection??

 

[SEC-Tom]

Ive also seen a job where a 63A breaker has been installed next to metre then a 16mm t+e run to consumer unit. Is this also bad practice??

I hate to say it but thats what iv done in the past, only due to the fact that I have been told to. I was in no position to argue it as I knew no better being a 2nd year apprentice. I just assumed that the 60a Isolator is the protective device if the T+E is damaged.

.fitting two 30ma rcds in line is a big no no !!!

So in a new dual RCD board. 100amp Main SW. and 2x30a RCDS is a no no?

 

[Spudnik]

.


So in a new dual RCD board. 100amp Main SW. and 2x30a RCDS is a no no?

What you are trying to achieve with those RCD's is to stop the whole CU going off should a fault on one circuit appear.

Thats why 2 RCD's protect 2 "sets" of circuits.

If you install an RCD ahead of the submain due to installation methods, this will not comply as, in effect, one RCD is covering the whole installation which is not permitted.

Make sense?

 

[SEC-Tom]

What you are trying to achieve with those RCD's is to stop the whole CU going off should a fault on one circuit appear.

Thats why 2 RCD's protect 2 "sets" of circuits.

If you install an RCD ahead of the submain due to installation methods, this will not comply as, in effect, one RCD is covering the whole installation which is not permitted.

Make sense?

Yeah iv got that, so you wouldn't install an RCD at the meter that would be a DP isolator?

 

[Spudnik]

Yeah iv got that, so you wouldn't install an RCD at the meter that would be a DP isolator?

Yes......as per DNO requirements if the sub is greater than 3 meters in length.