downgrading a cooker circuit

[Gringoking88]

Hi all,

Tomorrow I am installing a cooker circuit and the client wants me to install 6mm on a 32amp breaker as she wants the flexibility moving forward to upgrade her cooker to a more powerful one.

At present her new cooker's instructions say it must be hard wired and protected using a 13amp fuse. Im looking for advice please on how best to add the fuse protection, e.g. would you take a feed from the connection unit to a FCU and then to the oven or would you feed a 6mm to a 13amp FCU and wire straight to this baring in mind its on a 32amp breaker?

I know its a basic question and apologise in advance so please be gentle. I am registered with NICEIC but hardly do any work tbh so am not involved full time and only tend to do small jobs for friends etc and want to make sure im doing this as safely and best as possible.

Many thanks,

M

 

[telectrix]

i'd change the CCU to a D/P FCU. hard wire the cooker in to that. at a later date it can always be put back as was.

 

[Octopus]

Assuming the existing cooker is connected via an outlet plate, I would replace the outlet plate with a 13A socket or FCU

 

[Gringoking88]

i'd change the CCU to a D/P FCU. hard wire the cooker in to that. at a later date it can always be put back as was.

Hi D/P,

Wow that was a seriously quick response lol D/P im assuming you mean, double pole FCU? Do they generally have a maximum supply current rating and will they generally take a 6mm cable?

Thanks!

 

[westward10]

I personally wouldn't use an FCU for any significant load as modern accessories, no matter the manufacturer cannot cope with it so I would go for a socket.

 

[Gavin John Hyde]

Hi D/P,

Wow that was a seriously quick response lol D/P im assuming you mean, double pole FCU? Do they generally have a maximum supply current rating and will they generally take a 6mm cable?

Thanks!

You can get a 6mm into the back box with a FCU no problem, you can then use the FCU that has a flex outlet at the bottom you cut out / or a round hole for flex. then run appropriate flex to cooker. maybe using pre fitted flex if provided on cooker. The fact the cooker circuit is on a 32 amp mcb, is not a huge issue as the fcu with a 13 amp fuse in meets manufacturers instructions. If really worried why not replace the mcb for a lower rating, you can leave the current mcb with customer in the event she wants to upgrade later on, afterall a mcb will only be a couple of quid.

If you were going to have a go at sourcing the bits cliffuk.co.uk is the place to look for connectors and the like

 

[Gringoking88]

I personally wouldn't use an FCU for any significant load as modern accessories, no matter the manufacturer cannot cope with it so I would go for a socket.

Hi Westward,

The manufactures instructions specify the cooker must be hard wired otherwise this would be far the easiest way lol.

Thanks

 

[Gringoking88]

You can get a 6mm into the back box with a FCU no problem, you can then use the FCU that has a flex outlet at the bottom you cut out / or a round hole for flex. then run appropriate flex to cooker. maybe using pre fitted flex if provided on cooker. The fact the cooker circuit is on a 32 amp mcb, is not a huge issue as the fcu with a 13 amp fuse in meets manufacturers instructions. If really worried why not replace the mcb for a lower rating, you can leave the current mcb with customer in the event she wants to upgrade later on, afterall a mcb will only be a couple of quid.

Hi Gavin,

Thanks for the reply, I think I will go for the FCU with flex outlet idea that sounds the best and avoids the need for a cooker connection unit!

 

[westward10]

Fit a 47mm back box for the FCU to aid installation.

 

[Octopus]

I personally wouldn't use an FCU for any significant load as modern accessories, no matter the manufacturer cannot cope with it so I would go for a socket.

Funnily enough I would exactly the opposite ....................and go for the FCU

Some plugs on the market are complete pants .....................

 

[Octopus]

I would fit the CCU above the worktop ....................

 

[Gringoking88]

Fit a 47mm back box for the FCU to aid installation.

Westward,

Cheers for the tip, funily enough I ordered 46mm lol but who's counting!

 

[Gringoking88]

On a side note, there is a pre existing gas pipe behind it and a very dodgy pre existing terminal block where the ignition system for the gas hob is connected. Two questions, what would you guys do with the connector block, im thinking put in a junction box to improve safety (im not going to add it to the new cooker circuit). The hob is so old there are no instructions available anymore nor are there any current ratings etc. The second question is, is there a min distance the oven must be from the gas pipe? Im going to note on the certifciate I advise a gas engineer move the isolator to somewhere accessible? I have attached a pic FYI

 

[Gavin John Hyde]

^ Above - was the existing oven on a 13 amp plug socket then? i had assumed it was on a ccu and you wanted to change it to a fcu? but why have a fcu where it cant be reached? it sort of defeats having a switch if you cant use it

 

[telectrix]

On a side note, there is a pre existing gas pipe behind it and a very dodgy pre existing terminal block where the ignition system for the gas hob is connected. Two questions, what would you guys do with the connector block, im thinking put in a junction box to improve safety (im not going to add it to the new cooker circuit). The hob is so old there are no instructions available anymore nor are there any current ratings etc. The second question is, is there a min distance the oven must be from the gas pipe? Im going to note on the certifciate I advise a gas engineer move the isolator to somewhere accessible? I have attached a pic FYI

View attachment 41263

just tidy that up with a wagobox.

 

[Gringoking88]

Gavin,

Believe it or not, the oven was wired straight into the terminal block shown in the photo. I was thinking the following setup; MCB on board - 45amp cooker switch - fcu with flex outlet to cooker.

 

[Gringoking88]

^ Above - was the existing oven on a 13 amp plug socket then? i had assumed it was on a ccu and you wanted to change it to a fcu? but why have a fcu where it cant be reached? it sort of defeats having a switch if you cant use it

Gavin,

Believe it or not, the oven was wired straight into the terminal block shown in the photo. I was thinking the following setup; MCB on board - 45amp cooker switch - fcu with flex outlet to cooker (based on all the helpful info above). Mainly because it would make it simple to upgrade.

 

[MDJ]

Apologies wrong reply

 

[westward10]

Westward,

Cheers for the tip, funily enough I ordered 46mm lol but who's counting!

Won't be deep enough you need 47mm.