Disagreement between two electricians in new kitchen installation. Who's right?

[woz]

I'm having a new kitchen fitted with a bosch 7.2KW induction hob and bosch 3.45KW oven. Electrician 1 has decommissioned the old 6mm cable from the consumer unit and replaced it with a 10mm cable connected to the old 32a fuse on the RCD side of the consumer unit. From the 10mm cable he's put a 45a switch for the hob and proposed looping through another 45a switch for the oven. He says if the 32a fuse is found to be too low he'll replace it with a 45a one.

Electrician 2 says this is not safe. He says the 3.45KW oven is a 16a appliance an should be protected by a 16 or 20a fuse not 32a. He proposes putting a second small consumer unit on the end of the 10mm cable in a cupboard feeding just the oven with a 16 or 20a fuse inside. I don't want this, taking up valuable cupboard space. Another option would be to recommission the 6mm cable and connect it to a 16/20a fuse in the main consumer unit with RCD protection.

Who's right?? The kitchen fitter is returning tomorrow to remove the cupboard units to get to the plastered in 6mm cable and chase the walls for electrician 2 to fit a switch above the cupboard unless someone tells me the work done by electrician 1 is fine!

Thanks in advance.

 

[Darkwood]

Can you fill in your profile or provide you background here (what electrical knowledge do you have?), this allows us to tag you name and members can tailor there responses to suit.

We would need to know a lot more about the install to comment on fuse and cable sizes.

PS why have you got 2 conflicting Electricians on site, if they are from the same company it doesn't reflect well and I suggest you contact the boss and complain it doesn't give you good confidence in his employee's.

 

[woz]

Can you fill in your profile or provide you background here (what electrical knowledge do you have?), this allows us to tag you name and members can tailor there responses to suit.

done

We would need to know a lot more about the install to comment on fuse and cable sizes.

What more would you like to know about the install?

 

[Darkwood]

Cable length, installation methods, is there any de-rating factors to be applied like if the cables pass through insulation... just to get the ball rolling then members can give more accurate advice.

 

[woz]

PS why have you got 2 conflicting Electricians on site, if they are from the same company it doesn't reflect well and I suggest you contact the boss and complain it doesn't give you good confidence in his employee's.

The first electrician is the one I got in to do the work. The second electrician works for the company providing the kitchen installation to whom the kitchen fitter suggested I speak to after he saw the work electrician 1 had done.

 

[woz]

Cable length, installation methods, is there any de-rating factors to be applied like if the cables pass through insulation... just to get the ball rolling then members can give more accurate advice.

10mm cable length is approx 10 to 12m. On it's way from the consumer unit is doesn't pass through any insulation in the between floors ceiling void. Down kitchen wall it's clipped to the breeze block wall and plastered over.

 

[Octopus]

Never a good idea to get 2 independent sparks on the same job.

Not sure a 45A switch has enough space to accommodate 2 cables in the L & N!

 

[J.C.E]

the load of both the hob and the oven after diversity is applied (allowance due to appliances not running at 100% the full time) is around 27.5amps- aslong as the cooker isolator switch does not have a socket outlet on the switch?
10mm on a 32a fuse should be ok- may overload it at xmas time when your doing loads of cooking! how is the cable run? could possible upgrade the fuse to 45a

 

[woz]

Not sure a 45A switch has enough space to accommodate 2 cables in the L & N!

That's what I thought too. Electrician 1 proposes using a 2.5mm cable to loop through to the second 45a switch for the oven.

 

[Darkwood]

Without knowing too much at first impressions, your Kitchen Fitter Electrician sounds a bit clueless, I would go the your own electrician and ask him to fit the 40amp mcb anyway .. the hob and oven are classed as fixed loads and unless the manufacturers info' specifies reduced fusing which may be the case if it came with a standard flex and plug top then I would on the info provided go with your own Electrician.

 

[woz]

aslong as the cooker isolator switch does not have a socket outlet on the switch?

No socket outlet on the switch. It's a Crabtree double pole switch with neon.

 

[telectrix]

electrician 1 is right up to a point.... reason being that the fuse or breaker is there to protect the cable, not the appliance, and is rated accordingly. depending on the installation method of the cable, the current capacity may be reduced due to insulation. a 10mm cable has a current capacity of between 36A and 65A depending on how it's installed. ( insulation being the killer). the fuse/breaker rating should be below this value.



.elec.2 is talking out of his arse.

 

[Darkwood]

Never a good idea to get 2 independent sparks on the same job.

Not sure a 45A switch has enough space to accommodate 2 cables in the L & N!

1 switch to a duel outlet would be best IMHO

 

[telectrix]

1 switch to a duel outlet would be best IMHO

agree. i missed that bit. :jester:

 

[woz]

electrician 1 is right up to a point.... reason being that the fuse or breaker is there to protect the cable, not the appliance,

Electrician 2 said the cable that comes with the oven (the one with the kettle lead type of female plug) will burn before the 32a MCB goes if current is overloaded. Which is why he says a 16 or 20a MCB is necessary to protect the oven cable.