Mains cable earth wire too short for new cooker control unit

[thebladder]

I tried to replace my cooker switch last night but the mains cable earth wire is 2 or 3 cm short.

On the old one, the earth connection was on the middle of the plate, however on the new one it is on the far right.
(cables come in left side of mounting box)

Here's the link to the wiring diagram
http://www.free-instruction-manuals.com/pdf/p3856276.pdf
(P1, 45A Cooker Control Unit)

What are my options for extending the earth?

Can I use a 30A terminal block or do I need to crimp on an additional piece of earth cable?

Any advice much appreciated.

 

[EFLImpudence]

Can I use a 30A terminal block

Yes, if it will remain accessible or you could screw it to the back box (drill hole and use large self tapper and washer) and use another wire from the back box terminal to the switch

or do I need to crimp on an additional piece of earth cable?

You will need really good expert tool and crimp. From what you write it will probably too awkward to do well.

 

[Paul_C]

This is the sort of situation where it's a pity that Britain doesn't use wirenuts widely these days.

 

[PrenticeBoyofDerry]

if the earth cable is stranded, you stand a better chance of getting good contact using the crimping method, you can indeed use a suitable rated terminal block.
But after screwing the accessory back test you have good continuity of the earth/CPC

 

[thebladder]

The earth wire is 2.5mm solid core,

so better to go with the terminal block?

 

[PrenticeBoyofDerry]

The earth wire is 2.5mm solid core,

so better to go with the terminal block?

Solids are not ideal for crimping, they often pull a part. So terminal block would be my personally choice

 

[Alarm]

This is the sort of situation where it's a pity that Britain doesn't use wirenuts widely these days.

Nothing stopping the OP getting one.

 

[thebladder]

cheers guys, went with terminal block.

 

[ban-all-sheds]

And the result of your testing was...

But after screwing the accessory back test you have good continuity of the earth/CPC

 

[thebladder]

measured the resistance with my multimeter.
0.3 ohmns across the join.

 

[PrenticeBoyofDerry]

Is that the resistance of the CPC end to end from CU to accessory/appliance?
Or is it R1+R2 reading?
Or is it the resistance between one side of the terminal block to the other?
If the latter that is very high for such a short distance. I would except it to be reading 0.00 ohms.
You need to do the test between the Phase conductor and the CPC(earth), this known as R1+R2, they should be linked up at the CU via connection block, then the test taken at the furthest point of the circuit or in your case at the cable supplying the cooker.
The reason I suggested a test after the plate has fitted was to assure the connection was still sound after the connection block had been pushed back in to the box and had not come loose under stress.

 

[thebladder]

that reading was taken approximately an inch either side of the connection block. I got an identical reading across the wire before the block too.

Perhaps I should change the battery in my meter or get a new one.

 

[ban-all-sheds]

http://www.ebay.co.uk/dsc/i.html?_n...=0&_trksid=p3286.c0.m270.l1313&LH_TitleDesc=1

 

[thebladder]

whoops, meter was displaying 0.1 ohms not ohms so the reading was actually 0.03 ohms

 

[PrenticeBoyofDerry]

That looks like a decent buy for a man in need.
Metrel-61557