Consumer unit to be moved away from service head

[Chris]

Hi everyone.
I have been asked to relocate a consumer unit from a cupboard outside a house into the inside of the property. The main fuse and meter will be remaining outside however the run is about 6/7 metres long, i believe it states in BS7671 that the meter tails cannot exceed 3m in length.
would this require me to put a separate fused connection unit within the 3m of isolater and then run a 25mm SWA + 16mm earthing conductor from the fused connection unit, to the 6/7m away consumer unit location? If not who knows a better way?
thanks, chris.

 

[Spoon]

Yep, bung in a fused isolator mate.

 

[Baddegg]

Newbie question if I can,would a time delayed rcd comply in that instance?

 

[Pete999]

Newbie question if I can,would a time delayed rcd comply in that instance?

Hi everyone.
I have been asked to relocate a consumer unit from a cupboard outside a house into the inside of the property. The main fuse and meter will be remaining outside however the run is about 6/7 metres long, i believe it states in BS7671 that the meter tails cannot exceed 3m in length.
would this require me to put a separate fused connection unit within the 3m of isolater and then run a 25mm SWA + 16mm earthing conductor from the fused connection unit, to the 6/7m away consumer unit location? If not who knows a better way?
thanks, chris.

How far advanced are you in your career Chris, only to answer your question with any clarity it would help if we knew what your experiences are and what qualifications you hold, your profile throws up an error message.

 

[Leesparkykent]

What is the route from head/switch fuse to new location?

 

[Chris]

How far advanced are you in your career Chris, only to answer your question with any clarity it would help if we knew what your experiences are and what qualifications you hold, your profile throws up an error message.

no worries pete, i served a 4 year apprenticeship and have been qualified for 2 years and have my 17th edition (18th booked in), the 2357 NVQ and just recently passed the Inspection and testing 2391.

 

[Chris]

What is the route from head/switch fuse to new location?

It will be along the outside wall of the house which will be rendered over.

 

[Leesparkykent]

It will be along the outside wall of the house which will be rendered over.

Does the maximum demand require 25mm or could you get away with 16mm?

 

[buzzlightyear]

It will be along the outside wall of the house which will be rendered over.

what colour ?

 

[Leesparkykent]

what colour ?

Cement and sand coloured, mixed together one would guess......

 

[buzzlightyear]

is it black !I will blend in nicely .

 

[Leesparkykent]

is it black !

Is what black?

 

[Nigel]

Newbie question if I can,would a time delayed rcd comply in that instance?

What leads you to that?

 

[buzzlightyear]

Is what black?

the render .

 

[Baddegg]

What leads you to that?

Because that’s what’s been done in my house,not by me, this thread just reminded me so I thought I’d ask....
100A 100ma if memory serves me,not Home at moment.

 

[Nigel]

Because that’s what’s been done in my house,not by me, this thread just reminded me so I thought I’d ask....
100A 100ma if memory serves me,not Home at moment.

Are you on a TT?

 

[Baddegg]

Tns, but the consumer unit has been moved by someone before we bought the place as the original tails go into the rcd I mentioned earlier then leave the rcd in armoured and go to the unit under the stairs,

 

[Baddegg]

Apologies if I’ve hijacked your thread chris

 

[LankyWill]

the render .

Your really starting to annoy me, why do you always insist on taking threads of track. If your reply doesnt fall within the OP's question dont bother!

 

[Nigel]

Tns, but the consumer unit has been moved by someone before we bought the place as the original tails go into the rcd I mentioned earlier then leave the rcd in armoured and go to the unit under the stairs,

Then I cannot see why that RCD has been installed.

 

[buzzlightyear]

If your reply doesnt fall within the OP's question dont bother!

the op, is taking SWA has sub main to a new position and going to run it on the out side of the wall buried in render .me thinks it is bad idea .the op may has well run the SWA in the cavity if possible. or inside .

 

[Baddegg]

Then I cannot see why that RCD has been installed.

Thanks Essex,have been intending to look into this for a while this thread has just given me a kick up the arse,I believe it’s a 100a 100ma rcd main switch,not completely sure its time delayed I’ll have a look later

 

[Toneyz]

OP are you berrying the sub-distribution cable in the render as others are assuming that you are or are you cleating direct to render? What is your plan to run this cable?

 

[Chris]

Ma

Does the maximum demand require 25mm or could you get away with 16mm?

Maximum demand is 140-150A dont suppose you know if this falls within the allowance for 16mm?

 

[Chris]

OP are you berrying the sub-distribution cable in the render as others are assuming that you are or are you cleating direct to render? What is your plan to run this cable?

No i am not burying in render it is my fault for the assumptions as i wasnt very clear, the wall is due to be rendered over and it will be cleated and ran along the wall, then drilled through into property.

 

[Leesparkykent]

Ma

Maximum demand is 140-150A dont suppose you know if this falls within the allowance for 16mm?

No and it doesn’t for 25mm either. What kind of house is this.... A grow house?

 

[Ian1981]

Ma

Maximum demand is 140-150A dont suppose you know if this falls within the allowance for 16mm?

How did you conclude 140-150 amps ,have you simply added all the rating of the OCPD’s up?

 

[Baddegg]

Gonna have to be really creative with diversity to get them down to 16mm

 

[Chris]

How did you conclude 140-150 amps ,have you simply added all the rating of the OCPD’s up?

Yes i havent ap

No and it doesn’t for 25mm either. What kind of house is this.... A grow house?

Ah my mistake ive just added the rating of the MCBs up

 

[Toneyz]

Considering the OP has told Pete that he has done his 17th and 2391 bit concerning.

 

[Leesparkykent]

Yes i havent ap

Ah my mistake ive just added the rating of the MCBs up

The old school rule of thumb is to exclude the highest rated circuit breaker, add up up the rest of the circuit breakers, times this figure by 0.4 and add this figure to the rating of the highest rated circuit breaker you excluded.

 

[Leesparkykent]

Yes i havent ap

Ah my mistake ive just added the rating of the MCBs up

The old school rule of thumb is to exclude the highest rated circuit breaker, add up up the rest of the circuit breakers, times this figure by 0.4 and add this figure to the rating of the highest circuit breaker you excluded.

 

[Chris]

The old school rule of thumb is to exclude the highest rated circuit breaker, add up up the rest of the circuit breakers, times this figure by 0.4 and add this figure to the rating of the highest circuit breaker you excluded.

Thanks, it comes in at 76.8

 

[Chris]

Considering the OP has told Pete that he has done his 17th and 2391 bit concerning.

Still learning!

 

[Toneyz]

What is the main REC fuse rating 100A? if so need 100A metal switch-fuse with 80A fuse.

Still learning!

Not a dig Chris but thought that you would have learnt regarding diversity prior to you doing 17th and 2391.

 

[Ian1981]

I often use the highest load such as a shower for example then add 40% of the remaining loads.
Similar to lees method maybe Just the formula transposed

 

[Chris]

What is the main REC fuse rating 100A? if so need 100A metal switch-fuse with 80A fuse.

Not a dig Chris but thought that you would have learnt regarding diversity prior to you doing 17th and 2391.

Yes main fuse rating is 100A, thank you.

And i know it wasnt a dig! I work for a housing association and havent done any maximum demand calculations since my college days.

 

[Toneyz]

Yes main fuse rating is 100A, thank you.

And i know it wasnt a dig! I work for a housing association and havent done any maximum demand calculations since my college days.

Fair enough as said Pete said no profile anyway know where you're coming from now and yes if not doing all the things learnt at college you soon get rusty no offence meant Chris.
I would run a three core SWA the only thing if you are using 25mm is that the core that you are using for the earth it fits in the main earth terminal.

 

[Chris]

Fair enough as said Pete said no profile anyway know where you're coming from now and yes if not doing all the things learnt at college you soon get rusty no offence meant Chris.
I would run a three core SWA the only thing if you are using 25mm is that the core that you are using for the earth it fits in the main earth terminal.

Yes i only made this the other day i am yet to fill in all the details, will get round to it soon.
Yeah the supervisors do all the drawings and calculations so the rust appears to have set in haha! No offence taken.
That was my thought too im almost certain it will be too large for the MET i may have to figure something out for that.

 

[Octopus]

The old school rule of thumb is to exclude the highest rated circuit breaker, add up up the rest of the circuit breakers, times this figure by 0.4 and add this figure to the rating of the highest circuit breaker you excluded.

I find multiplying by 0.25 a better calculation ......