Connecting 10mm cable

[jackofnotrades]

I'm routing a cooker circuit (10mm cable; 32amp MCB) and bought 25m of cable - only to find that it's 3m short of what I need - damn measuring tape . What sort of junction box/connector do I need to attach a further 3m to the other 25m? I have some heavy duty 30amp junction boxes but they state that they are for 4mm cable max. I've seen some 60amp choc. boxes but do I need 60amp?

jackofnotrades

 

[securespark]

You live up to your name, I'm afraid, with logic like that. Change the whole length and put it down to experience.

 

[jackofnotrades]

securespark

Thanks. I have considered this and it is what I'm resigned to doing, I just wanted other views. Call me mean (no don't, it's not true) but I don't want to buy 50m of cable if I don't have to (25m not enough, buy it by the meter and it's too expensive). I'm not going to use the excess for anything.

Can you or someone advise why it is possible to join 2.5mm cable etc (at sockets or spurs via junction boxes etc) but seemingly not 10mm? I'm sure there is good reason but I would like to know why. I'm here to learn.

I do live up to my name - but I'm not stupid, when I'm not sure or don't know I seek advice and generally take it. Once again, thanks for your advice securespark.

jackofnotrades

 

[mildmanneredjanitor]

Why 10mm?

Isn't this large for cooker circuit??

Is it to do with the length? F'nar F'nar! Derating rules etc...

6mm is more commonly used and ok protected by a 32a mcb.

I'm sure one of the clever ones will tell you for sure (I'm not one of them )

Also, if you quote the power of the cooker this will help the real sparkies determine the correct size of cable for your installation.

 

[securespark]

It is possible, and there is the gear out there to do it. It's just much better to have a whole piece without a join. That goes for anything....the fewer the joints the better.

Think of it as the cost of a pub night out & curry. You can sacrifice that, can't you?

Pray tell what you are being charged for 50m of 10mm2 T&E? It's not that expensive from the right place..

One local w'saler can do 50m for 51.42 ex.

Compare that to an old catalogue I have going back to 1996 - 86.89!!

 

[AdamW]

Jack,

The problem with joining cables is that you still need to make the joint "accessible". There are plenty of discussions on what is accessible on this forum, but the consensus seems to be that buried in a wall is NOT accessible

Now, obviously you are loathe to go and buy a 50m length of 10mm cable, it is pricey stuff. (about £30 for the length you need) However, if this is a job you are doing in your own house, think of how much easier your sleep will come knowing that your kitchen won't burn down in the night. And if it is someone else's house, imagine how bad you would feel if the house burned down the day after. Even if it turned out your cable wasn't to blame, how low would you feel for those weeks before the investigation came out?

I think as Securespark says, you should put this one down to experience. You never know, you may need some 10mm cable at some point in the next few months. With the new colours coming in someone is bound to want to buy some to avoid having to sheathe all their existing cables next time they install some new cable.

As to why joining 2.5mm cables is OK and 10mm is not: I agree that at first glance it doesn't make much sense. However, 10mm is usually used for circuits that draw a LOT of current. 2.5mm is used for rings and these are circuits that draw (comparitively) little current. With your 10mm cable you really want to minimise the voltage drop. Hence one run of cable.

However, are you sure you need as much as 10mm on this? I hope an electrician will give us the proper figure here, but if you are on a 32 MCB wouldn't 6mm be plenty big enough (although it would only save £3 or so!)? The 28m run is the factor in the equation I am not sure of. Good on you for using 10mm either way, bigger cables are better.

 

[AdamW]

Compare that to an old catalogue I have going back to 1996 - 86.89!!

That's the commodities market for you, I bet you will find copper piping has got cheaper by a similar factor too.

 

[jackofnotrades]

All of you thanks. The consensus seems to be that although it is possible I should be cautious, cough-up and forget the curry and beer this weekend. I'll take the advice.

BTW it's a double oven bought on the internet (arrives tomorrow morning) with gas hob. I cannot find details on the web about power consumption other than 30amp connection required. I assume details will arrive with cooker tomorrow. My book states that for a cooker circuit with a 30amp MCB with a cable run over 21m it should be 10mm. Up to 21m then it can drop to 6mm.

The TLC quote for 50m of 10mm is £65.00 plus VAT. I will shop around - but I don't have a car and the nearest wholesalers is about 45min walk away - how much does 50m weigh? - but this is my problem!

Didn't know about the changes to cable colour (not being a spark) - so I'll look upon my excess cable as an investment. Who knows, one of you might be contacting me in a few months time when none is left?

jackofnotrades

 

[securespark]

Adam

although copper prices have shot up just recently. Apparently China have bought shed-loads of the stuff.....

 

[securespark]

If the two items were ONE appliance, then the total load would be some 10kW / 230V = 43.47A, so a single 6mm 32A circuit would not be sufficient to supply it.

The circuit should be in 10mm and on a 40 or 45A MCB.


The above is a snippet from another topic, courtesy of FWL Engineer.

You can see that it would not be impossible to want the extra capacity in a cooker circuit. You can have this with 10mm2 just by changing the mcb in future, so Jack is to be applauded for thinking of future expansion.

 

[kendor]

Does the cable make it into the kitchen? If it's just the double oven that's the problem can it not be built into a unit near to where the cable ends, have you already installed the unit for the oven?
and the gas hob will obviously go where the gas supply is, does it matter that you have to walk between them?

 

[securespark]

You What???

I know, my cable is too short, let's rearrange the whole f*cking kitchen instead of buying a new piece....

This iso switch cannot be more than 2m from the appliance.

 

[AdamW]

You jest, but stranger things have happened. We have all heard the one about the size of a Space Shuttle solid rocket booster being determined by the width of a railway tunnel, which can be traced back to the width of a horse's behind.

You could always climb onto the spool and roll the 50m of 10mm back home, like a lumberjack rolling logs down the river

 

[securespark]

Ken

The other thing you have to consider when laying out a kitchen is the working triangle (cooker, sink, fridge/food store)

 

[darren7]

jackofnotrades,

what about the Double pole switch, and then the outlet, you are doing it correctly?