No cooker isolator???

[TPES]

Done a consumer unit change on a property, all circuits tested ok only problem i've come to now is I can't see cooker isolator in kitchen?, looked behind units and back of draws, my guess is it has been plastered over. How now would I test this circuit without dissconecting from back ofthe big double oven/hob.. What are my options?

 

[Spudnik]

You havent got any, other than disconnect the oven.

Whilst you are at it, you may want to drop an isolator in and then connect the oven to that as per the norm.

It may be that when the kitchen was refitted, the isolator was done away with.

 

[TPES]

So there's no other option? What if the customer doesn't want to pay for me to pull kitchen units out trace the cable back and fit a new isolator?

 

[beaver74]

So there's no other option? What if the customer doesn't want to pay for me to pull kitchen units out trace the cable back and fit a new isolator?

test for insulation l+n to earth
test earth r2 meathod
and note it on cert

 

[TPES]

test for insulation l+n to earth
test earth r2 meathod
and note it on cert

Quick thought.. Can Zs be calculated? Suppose I would need to know how much bigger the cpc is to live in 6mm (as in 1.67 x for 2.5mm T&E)..

Or can it just not be calculated?

So I won't be breaking any rules by not installing a cooker isolator aslong as I note it on cert?

 

[pushrod]

Quick thought.. Can Zs be calculated? Suppose I would need to know how much bigger the cpc is to live in 6mm (as in 1.67 x for 2.5mm T&E)..

Or can it just not be calculated?

So I won't be breaking any rules by not installing a cooker isolator aslong as I note it on cert?

Zs = Ze +( R1+R2)

You can calculate R1+R2 from table 9A (App 9) of the On Site Guide if you know the length of the run.

This value will probs be a bit higher than the real value.

 

[TPES]

I understand what your saying but can't get an R1+R2 Reading, and don't know
run length.

 

[pushrod]

Reckon you are disconnecting the oven then

Edit : or as beaver said if you have a long enough wandering lead you can work out R2 from the casing of the cooker and then calculate R1 as it will be the same length as the cpc

 

[Johno]

If I were you I would test Zs and R1+R2 at oven terminals and make a note on cert that there's no isolator. Is it 6mm2 T+E at terminals, just thinking that there may be a join somewhere, but if visible cable is correct and tests ok, then that is all you can do. but tell the customer first, they might agree to fit one