Replacement oven - incorrect switch?

[luckyNot]

Hi,

I just moved in to a new house and have encountered a number of 'interesting' wiring scenarios, but for now I will focus on the only one I think is ok ..

I have a 20A MCB, 4mm clip direct running 10 meters to oven isolator switch. The oven is 4Kw, so about 16A. There is 1 mtr of 2.5 flex between the oven and mounting plate - so rating 25A.

I need to replace the isolator switch. From what I can see a standard cooker switch is 45A, but isolator switches at 20A are available though not labelled 'cooker'. Is there a best practice here e.g. is putting 45A switch on a 2oA circuit misleading, or using a 20A for a cooker wrong?
Thanks

 

[telectrix]

you can fit a 45A isolator no problem, as the 45A is the max. rating of the isolator, any thing under a 45A load will just mean that it's not being overloaded.

 

[Strima]

20 amp will be fine as the MCB is rated at 20 amps.

 

[DJ Ovengloves]

The fact you’re askjng the question means you shouldn’t be changing it!

How many hundreds of thousands have you just spent, but yet you’re trying to save cash on something that could kill?

 

[telectrix]

or buy a labeller machine and label the existing switch.

 

[luckyNot]

The fact you’re askjng the question means you shouldn’t be changing it!

How many hundreds of thousands have you just spent, but yet you’re trying to save cash on something that could kill?

I am confused, but it may be I phrased my questions poorly. I wanted to know if the current install, using a 45A switch was wrong given the rating of the circuit. The responses here confirm that a 45A is ok (and not misleading), so I can replace like for like.
I am replacing the switch due to it being dirty and cracked.
Given this, is your view that I require an electrician to do this? If so, why?
Thanks

 

[DJ Ovengloves]

Not once have you mentioned cracked switched, more “interesting wiring”, with a load of pseduo spark speak and then misunderstood something basic in regards to ratings of the switch, which points to an amateur.

Why is the switch cracked..excessive heat, physical damage etc? How are you measuring that the cpc is viable etc?

 

[Wilko]

Hi - if there any issues with making the connections then there is risk of fire due to ohmic heating for example. It's very important for the earthing to be correctly carried through too.

 

[luckyNot]

Thanks for the quick response. I think we can agree my opening post was poorly worded/described
Pseudo spark speak it is. I looked on the forum and saw these were the sorts of details that people ask for, so I provided them.
What I was trying to understand, with regard to switch rating, was whether or not it was misleading putting a 45A switch on a circuit that did not appear to be be capable for running 45A. The responses suggest this is common practice and not misleading. So it seems I have indeed misunderstood something basic.
I am an amateur and this is a post in the DIY forum. I have chosen to ask here before acting for just this reason.
Following your question regarding damage, I have opened the switch and looked inside. There is no burn/electrical damage, the face plate is cracked but not heat marked.
I had to Google 'CPC' and I cannot make full sense of what I found. I think what you are asking is whether the earth feed is big enough for things to be safe. From what I can see in the switch the feed is using earth from the 4mm cable. Is this a concern?
Thanks again

 

[Deleted member 26818]

CPC = Circuit Protective Conductor, which is the earth wire you see in cables.
45A is fine, anything else and you run the risk of having to change the back box, which could mean chiselling out the old one and then filling a gap, etc.
Make certain all the conductors are terminated correctly.