Shower upgrade on a very old consumer unit

[sparky in training]

Hi all

Came across a situation today where somebody was enquiring about upgrading their shower from an 7.5kw to a 9.5. Apparently he had a very old consumer unit with only 4 circuits. lights up and down, sockets up and down. cooker and existing shower. I wanted to know how you guys would tackle this job? I'm aware of the requirements of ADS and cable sizing etc however how would you have dealt with he old fuse box, this contained the rewireable fuses.

Could you upgrade one of those fuses to say 45amp and then go into a new consumer unit with a MCB / RCD or RCBO or would you recommend a new CU?

Would the regulations see this as an alteration to an existing circuit seeing as the cabling will require upsizing? If it is classed as a new circuit can the existing CU be used as it is metal and just put an RCD in?

 

[Leesparkykent]

A lot of the main switches on these boards would only be rated to around 60A. I would discuss the benifits of upgrading the existing board and if that was a no go then I would be pricing to install a 2 way board with an RCD by splitting the tails.

 

[telectrix]

split the tails into th old CU using henley blocks. then fit a "garage board" RCD and 2 MCB slots. 40A MCB for shower, thren divert your shower cable from old CU to your new one. assuming it'd 6.0mm and man enough for the 9.5kW, no derating due to itchy-poo. test and cert. then the old CU and what it feeds is none of your concern.

 

[telectrix]

beaten to the draw by fast fingers lee.

 

[Ian1981]

If installing a 2 way DB for the shower circuit,As it's in a special location I would also consider the requirement of rcd protecting any circuit contained in the bathroom, despite not working on say the lighting you are changing the shower and the characteristics of the circuit by providing rcd protection to the shower.
Supplementary bonding the circuits in the bathroom to any extraneous parts is also an option.

 

[Octopus]

I would discuss the options with the client, and recommend a RCBO board ......

 

[westward10]

Replace the whole thing adding a garage board by splitting the supply is the house basher option.

 

[Octopus]

Replace the whole thing adding a garage board by splitting the supply is the house basher option.

That does not make sense!

 

[Phil Thompson]

I'd suggest the new CU to the client first then offer shower board and cut tails second.

All depends on their budget I guess.

 

[Phil Thompson]

That does not make sense!

He forgot the , between thing and adding lol

 

[westward10]

That does not make sense!

I mean replace the existing CU as opposed to lashing in a garage board.

 

[Leesparkykent]

I don't see how splitting the tails and adding a board for the shower is the "house basher" option.....If the customer hasn't the budget for a CCU change then you are doing them an injustice by not offering the option of doing it this way. I would go as far to say that not offering the option could be seen as trying to rip the customer off as you only want the CCU change out of it.

 

[Ian1981]

I don't see how splitting the tails and adding a board for the shower is the "house basher" option.....If the customer hasn't the budget for a CCU change then you are doing them an injustice by not offering the option of doing it this way. I would go as far to say that not offering the option could be seen as trying to rip the customer off as you only want the CCU change out of it.

Don't bite lee

 

[Leesparkykent]

Don't bite lee

lol....it's just some people don't seem to live in the real world and seem to see everything through rose tinted glasses....Yes in an ideal world the customer would go for the CCU change but some people just can't afford it. I've had to do similar for an OAP in the past.

 

[Ian1981]

lol....it's just some people don't seem to live in the real world and seem to see everything through rose tinted glasses....Yes in an ideal world the customer would go for the CCU change but some people just can't afford it. I've had to do similar for an OAP in the past.

I've done the same because the existing cu had tinned copper stranded cables and a poor overall IR , so rather than touch the existing wiring,I added a separate consumer unit and installed a new circuit for the shower and lighting in the bathroom.
Electrics isn't always straight forward and you have to adapt while trying to keep within the regulations as far as reasonably practicable.