Any problems with this.....

[Ydraiggoch]

Planning a new kitchen install and will be looking to wire in new 7kW Induction Hob & 2 x 3kW Ovens

The ovens will be fed off their own Radial circuit, which I plan to run a 4mm Cable (~ 10m run max) to 2 x 20A Grid switches for each oven. - I will run 2.5mm to each oven from their respective switch. This Circuit will be protected by a 32A Breaker.

The Hob will again be on its own radial circuit and am thinking a 4mm cable and 32A protection will be sufficient based on;

7000W / 230V = 30A

But when considering diversity....

10A + 30% of 30A + 5A (for socket) = 24.1A

So, this is all good right?

Where I am not to sure of though is that I would like to run this cable in a metal conduit under the floor, which I think I'm right in saying is a no go for as per the regs (I may be wrong here). But in order to protect the cable against mice & possibly rats....don't ask! I want to run about 3m of the cable in conduit.

How would this effect my design? Should I step up to 6mm to account for this. And do you have any good suggestions for protecting T&E against Mice & Rats?

Cheers

 

[RF Lighting]

4.0mm² in steel conduit will be fine. Make sure you earth the conduit.

Steel conduit or using an alternative type of wiring is the only way to really guarantee protection against fauna.

 

[SlipperySid]

I would like to run this cable in a metal conduit under the floor, which I think I'm right in saying is a no go for as per the regs

No, you are very wrong.

...etc

Why not just answer the question or ignore?

 

[Ydraiggoch]

Thanks for the replies guys.

Am I right in saying that this would not be normal practice? If memory serves me right, the regs (handbook) suggests only having it in no insulation conduit etc. I don't have it to hand, but know that the table only suggests one method of install?

Although, technically it should be safer than having a Rat chew through the cable and then having to rely on protection back at the board. Prevention is better than protection I guess!

Thanks again

 

[winston1]

I would like to run this cable in a metal conduit under the floor, which I think I'm right in saying is a no go for as per the regs

No, you are very wrong.

...etc

Why not just answer the question or ignore?

He did answer one of the questions.

 

[ban-all-sheds]

Can somebody please confirm that it is now site policy that testing, EICs etc are no longer required for new circuits, and also please point me at the relevant Amendment to the Wiring Regulations, as I seem to have missed that change.

 

[RF Lighting]

Thanks for the replies guys.

Am I right in saying that this would not be normal practice? If memory serves me right, the regs (handbook) suggests only having it in no insulation conduit etc. I don't have it to hand, but know that the table only suggests one method of install?

Although, technically it should be safer than having a Rat chew through the cable and then having to rely on protection back at the board. Prevention is better than protection I guess!

Thanks again

It would be a little unusual to find steel cable containment in a domestic property, and not at all uncommon on a commercial property, but if that's what is required to protect your cables then that is what you must do.

You take the figure quoted in the regs, and de-rate it by all the appropriate factors such as conduit, insulation, fuse type etc.

I've done the calculation for you and as long as the cable or the conduit do not pass through insulation, 4.0mm² cable will be fine for your proposed circuits.

 

[ban-all-sheds]

I don't have it to hand, but know that the table only suggests one method of install?

Table 4A2 lists 54 methods.

 

[Ydraiggoch]

Thanks all for your replies.

It's good to confirm my thoughts with other sparks out there. I will go with the 4mm in Conduit for (mechanical)protection. As there's no insulation it will be passing through, and under the floor is 'well ventilated' I'm confident that this will be suitable.

I'll certainly cross check the Handbook myself once back home (currently offshore) but am now happy with my design.

Cheers