multistrand singles for electric cooker

Hi all,

I need to install my in-laws cooker when they move to their new house. As I don't have any 10mm^2 T&E lying around I wondered if there was any regulation preventing me using 10mm^2 stranded singles in conduit? I tend to think that this would be a nicer installation ... but am worried if there are any legal implications with this.

Cheers, Mark

Reply to
marpate1
Loading thread data ...

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember " snipped-for-privacy@yahoo.co.uk" saying something like:

10mm? Must be a helluva cooker.
Reply to
Grimly Curmudgeon

That's perfectly acceptable providing you use the proper materials. Check the current rating for whatever installation method you're using. Note that you can't parallel up thinner conductors to make up 10mm - you need to use the right sized singles.

Reply to
Andrew Gabriel

10mm sq. I'm kind of thinking worse case here as I've not seen the cooker yet. Of course if the cooker does actually require 10mm sq. and the rest of the installation isn't .. then I'll be walking away pretty rapidly :)
Reply to
marpate1

Great .. .many thanks. I didn't even consider using multiple thinner conductors .... I must be losing my touch :)

Turns out the only cable I have available is red & black 8AWG ... so I think that I may just order some cable off ebay and save any future hassle!

Reply to
marpate1

snipped-for-privacy@yahoo.co.uk wibbled on Monday 04 January 2010 12:05

It needs to be in continuous conduit until it's junctioned back to T+E, or reaches the CU.

Are you sure you need 10mm2? *Very big* cooker? Or conduit in loads of insulation? I'm doing mine in 6mm2 on a 32A MCB which is a fairly normal setup. You are allowed to factor in diversity (ie it's not necessary to total up every ring, grill and oven and call that the design load, because even if you use everything, thermostats will start switching elements in and out anyway.

From the IEE OnSite Guide (17th) Appendix 1 (not verbatim)

Cooker circuits: For cookers in residences, allow

10A + (30% of the max full load of cooking appliance in excess of 10A) + (another 5A if the cooker switch contains a 13A socket).

Without a 13A socket that buys you:

F = full load amperes

Design current = 32 = 10 + 0.3x(F-10) =>

(32-10)/0.3 = F-10 =>

F = (32-10)/0.3 + 10 =>

F = 83.3 A or 19kW cooker as stated max full load

-----

With 13A socket,

32 = 10 + 5 + 0.3x(F-10) =>

(32-10-5)/0.3 = F-10 =>

F = (32-10-5)/0.3 + 10 =>

F = 66.7A or 15kW

HTH

Tim

Reply to
Tim W

Thanks Tim,

I chose 10mm2 as worst case as I have no idea what they have at the moment. From the calculations though I think that this way of an overkill and 6mm2 does sound much more sensible.

Many thanks! Mark

Reply to
marpate1

snipped-for-privacy@yahoo.co.uk wibbled on Monday 04 January 2010 13:07

I've just checked the Range Master Elan 110 wide all electric range cooker:

formatting link
total full load is stated as 15.9kW so I's say you are on safe ground with a 32A circuit... And that's a bloody big cooker by domestic standards. If you want to cut some slack, leave the optional 13A socket in the cooker switch out. I think it would be hard to find a 19kW domestic cooker, though I wait to be proved wrong!

Cheers

Tim

Reply to
Tim W

Thanks Tim!

Given their available space and budget I would expect a pretty standard single oven jobbie - certainly nothing this large.

I've ordered a couple of metres of 6mm2 T&E off ebay (didn't realise it was so cheap having only checked prices in the sheds before now).

Thanks again, Mark

Reply to
marpate1

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember " snipped-for-privacy@yahoo.co.uk" saying something like:

As Tim said, 6mil will be fine.

Reply to
Grimly Curmudgeon

snipped-for-privacy@yahoo.co.uk wibbled on Monday 04 January 2010 13:45

Another way to look at it is 15kW is more or less double the max sustained load that a 32A circuit can handle.

A type B MCB (and its equivalent fuses) will take around 1/2 hour to trip on an overload of double the rated current. This is safe as the cable takes time to heat up to exceed its operating temperature too - in fact the fuse curves are designed with this in mind.

So even if someone turned every element on from stone cold at once, there will only be an interval of typically less than that before thermostats start cycling the oven elements.

If you dump 15kW into a kitchen for any length of time you are going to get very warm indeed. I can heat most of my ground floor with about 8kW when it's -3C outside and half my roof insulation is missing.

:)

Reply to
Tim W

snipped-for-privacy@yahoo.co.uk wibbled on Monday 04 January 2010 13:45

Wait around for a bit and see if anyone (eg Adam, Andrew Gabriel or John Rumm to name a non exclusive few) spot anything that's cobblers with what I've written, but I'm fairly confident of the calcs I gave you.

It's not hard stuff, but I was feeding my son while typing that lot(!)

Double check it yourself - the statement re diversity I typed from the OnSite is accurate though... Assume V=230V for wattage calcs (even if you have 240V).

Reply to
Tim W

As stated 6mm is most likely fine.

The French do an interesting method whereby singles are in flexible conduit and just uncoiled into the channel you made (in zone I presume).

That potentially makes for easier replacement in future in terms of time & disruption (chop open a corner, drag out cable) compared to oval (sheathed cables often jam) & rigid conduit (better with studded walls). It seems the French do not require the conduit to be fixed first & cables drawn in later (like BS7671). The flexible conduit just enters backboxes rather than using conduit fittings AFAIK.

Reply to
js.b1

The 16th edition OSG advice was that a 30 or 32A circuit is usually appropriate for a household cooker up to 15kW.

And voltage drop is certainly not a problem if the OP has only had to buy a couple of metres of cable.

A 6mm 32A supply sounds the correct way to go

Adam

Reply to
ARWadsworth

Yes, but at least some of their flexible conduit is ridged internally and makes pulling a new core in at a later date problematic. As well as that their crappy backboxes tend to fall out of the wall when you pull a plug out!

SteveW

Reply to
Steve Walker

Fishing tape would be necessary... wishfulfishing tape.

Ah, that's the built in automatic extension cable facility :-)

Reply to
js.b1

I like it ;)

My parents have a holiday home over there and when we borrowed it, they carefully made socket covers, so that our youngest wouldn't be able to stick his finger or anything else into the unshuttered sockets and he promptly pulled one right off the wall, exposing the live wiring and terminals :(

As well as that, there's the really poor double sockets where each is hardwired in reverse to the other, so you can't guarantee which is live and which is neutral when you plug the (admittedly rarer these days) equipment for which this matters in.

SteveW

Reply to
Steve Walker

French sockets aren't polarised. Whilst you can't reverse an earthed plug, it's not defined which connection is live and which is neutral. Every double socket and 2-way adaptor I've seen has them hardwired the opposite way around. In some areas of France, there is no neutral (neither main conductor is near earth potential).

Actually in much of Europe the socket outlets aren't polarised. It's just with the French/Belgium ones, they look like they are because the plug can't be reversed, but actually they aren't.

Reply to
Andrew Gabriel

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.