Supply for shower board

[madmaz]

been to a job today where a seperate fuseboard has been fitted to supply an 8.5kw shower the supply and load cables for this board are 6.0mm twin and earth, the shower fuseboard has a 32a mcb and an rcd main switch and labelled up shower only, the feed for the seperate fuse board (only room for the one circuit) is 6mm twin and earth direct from the main Fuseboard incoming terminals is this ok ? The main fuse is 60a as the load is fixed at 32a and the 6mm cable is suitable for this the run between consumer units is surface mounted and double insulated less that 300mm long the only protection for the 6mm cable feeding the seperate fuseboard is the main fuse 60a no overloading of this cable is possible as the upstream 32a mcb restricts this the only issue would be a short circuit should the cable be damaged which with the PFC reading 1.2ka this is irrelevant isn't it ? Just wondering, Or have I misunderstood

 

[westward10]

Connecting from the live side of an existing board is poor, probably leaves no single means of isolation and quite frankly is the method of a Housebasher.

 

[Piratepete]

been to a job today where a seperate fuseboard has been fitted to supply an 8.5kw shower the supply and load cables for this board are 6.0mm twin and earth, the shower fuseboard has a 32a mcb and an rcd main switch and labelled up shower only, the feed for the seperate fuse board (only room for the one circuit) is 6mm twin and earth direct from the main Fuseboard incoming terminals is this ok ? The main fuse is 60a as the load is fixed at 32a and the 6mm cable is suitable for this the run between consumer units is surface mounted and double insulated less that 300mm long the only protection for the 6mm cable feeding the seperate fuseboard is the main fuse 60a no overloading of this cable is possible as the upstream 32a mcb restricts this the only issue would be a short circuit should the cable be damaged which with the PFC reading 1.2ka this is irrelevant isn't it ? Just wondering, Or have I misunderstood

If I read your post correctly the cables between the 60 amp cutout and the board are only 6sqmm. They have to be rated for 60 Amps whatever is downstream. In this case if Reference Method C, 2 single 10sqmm cables (tails) and a 10sqmm earth are required (assuming a PME supply). You could use 10mm T&E but run a seperate 10mm earth.
I would not connect these into the incoming terminals on the main board. It's messy and you run the risk of dodgy connections. I'd supply both boards from Henley Blocks.

Pete

 

[westward10]

If I read your post correctly the cables between the 60 amp cutout and the board are only 6sqmm. They have to be rated for 60 Amps whatever is downstream. In this case if Reference Method C, 2 single 10sqmm cables (tails) and a 10sqmm earth are required (assuming a PME supply). You could use 10mm T&E but run a seperate 10mm earth.
I would not connect these into the incoming terminals on the main board. It's messy and you run the risk of dodgy connections. I'd supply both boards from Henley Blocks.

Pete

6.0 tails are fine and if it is not supporting bonding so is 6.0 earthing conductor. The correct professional way to supply the shower is to replace the existing CU thus leaving a single means of isolation.

 

[Leesparkykent]

Or a double pole switch in the tails between meter and 1st/main CU. Henley block the tails after the double pole switch to feed shower board.

 

[westward10]

Or a double pole switch in the tails between meter and 1st/main CU. Henley block the tails after the double pole switch to feed shower board.

Tis a better option.

 

[madmaz]

Can I say this install is dangerous, and condem it ? It's been like that for years and in my mind looks to be neatly installed and electrically sound if as in so many cases you class the main fuse as the main isolator all terminations sound and no risk of overload just unorthodox

 

[Piratepete]

6.0 tails are fine and if it is not supporting bonding so is 6.0 earthing conductor. The correct professional way to supply the shower is to replace the existing CU thus leaving a single means of isolation.

Why are 6mm tails ok in this case? is it due to the shortness. What reg supports this?
Pete

 

[madmaz]

Why are 6mm tails ok in this case? is it due to the shortness. What reg supports this?
Pete

Can't be overloaded can only draw 32a maximum as there is a 32a ocpd fitted in the shower board

 

[Leesparkykent]

Why are 6mm tails ok in this case? is it due to the shortness. What reg supports this?
Pete

433.2.2 and 433.3.1

 

[westward10]

Can I say this install is dangerous, and condem it ? It's been like that for years and in my mind looks to be neatly installed and electrically sound if as in so many cases you class the main fuse as the main isolator all terminations sound and no risk of overload just unorthodox

It probably isn't dangerous as you said been like it for years. You can't class the main fuse as isolation, the property should have a single point of isolation, it is a domestic property and there is no excuse for ad hoc additions.

 

[madmaz]

It probably isn't dangerous as you said been like it for years. You can't class the main fuse as isolation, the property should have a single point of isolation, it is a domestic property and there is no excuse for ad hoc additions.

It just looks wrong then, there would there be no Issues had it been supplied from the load side of the switch then ?

 

[Leesparkykent]

It just looks wrong then, there would there be no Issues had it been supplied from the load side of the switch then ?

IET guidance note 2 says something along the lines of....A dwelling can have more than 1 electrical installation therefore one main switch is not required to isolate all consumer units simultaneously providing the consumer units have an integral main switch. Its a requirement that each device used for isolation to be clearly identified by positional or durable marking to indicate the installation it isolates. How ever the guidance notes are just that guidance and I agree its prudent to have a single point of isolation.

 

[madmaz]

So other than it being unorthodox it's neither dangerous or broken any regs in reality ?

 

[westward10]

IET guidance note 2 says something along the lines of....A dwelling can have more than 1 electrical installation therefore one main switch is not required to isolate all consumer units simultaneously providing the consumer units have an integral main switch. Its a requirement that each device used for isolation to be clearly identified by positional or durable marking to indicate the installation it isolates. How ever the guidance notes are just that guidance and I agree its prudent to have a single point of isolation.

I would read this as different tariffs of supply like off peak. A dwelling isn't a large installation which may require more than one supply. To me no excuse in a dwelling.