No electricity to electric shower. No pull switch installed.

[norm]

what if it goes again and it catches on fire? A switch wouldn't just fail for no reason. Esp one like a shower thats rarely turned off. But anyway fingers crossed for ya

Agreed, anything that is causing something to melt is not right. Possibly the MCB isn't tripping correctly.

Definitely not something to 'wing it', even at ordinary currents let alone the 40A this is pulling.

 

[413x]

So in end got electrian round. He's changing the ancient CU and installing a pull switch for the shower.

Looks like the old owners got someone in who bodged the job

Including a 100A rcd on a 100A supply which I never noticed

 

[dale1uk]

I see you got an electrician in now, but thought I'd point out that a 40a MCB is undersized for a 10.5kw load. Watts÷voltage=amps so 10500÷230=45.65

Presumably your electrician has replaced the MCB for a 50a and fitted a 50a DP pull switch?

Also, depending on the cable routing/installation type then you could be right on the limit for 10mm t&e

 

[413x]

Actually no. He said 40 was fine. But the cooker switch has been changed to a pull cable.
I'm not convinced it won't go again myself. And there was no burn etc on switch this time. No idea what issue was. But there is completely new cable between shower and pull cord now

 

[Jez]

I see you got an electrician in now, but thought I'd point out that a 40a MCB is undersized for a 10.5kw load. Watts÷voltage=amps so 10500÷230=45.65

Presumably your electrician has replaced the MCB for a 50a and fitted a 50a DP pull switch?

To second this, a 10.5kw load is going to pull more than 40a….that breaker isn’t large enough. Big boy said the same above too I think. Note that it won’t actually be as much as 45 as you should find that U.K. voltage is actually a shade over 240 rather than 230.

 

[NoobCannon]

To second this, a 10.5kw load is going to pull more than 40a….that breaker isn’t large enough. Big boy said the same above too I think. Note that it won’t actually be as much as 45 as you should find that U.K. voltage is actually a shade over 240 rather than 230.

not anymore, I do lots of daily testing and find that the average voltage seems to be 232-236. Unless it varies by area of course but this is across an entire county (essex)

 

[Jez]

not anymore, I do lots of daily testing and find that the average voltage seems to be 232-236. Unless it varies by area of course but this is across an entire county (essex)

Interesting, it is firmly over 240 around here in Oxon at idle (although i have only ever had cause to test a few houses). My main house at rest is always over 240, although it is amazing to see the voltage drop when you heavily load the supply (low 220s not uncommon when loaded up).
Interesting that your area differs, i assumed it would be the same nationwide.

 

[BigBoy]

not anymore, I do lots of daily testing and find that the average voltage seems to be 232-236. Unless it varies by area of course but this is across an entire county (essex)

Most of the south west is 230-238 hardly ever see 240v any more, apparently it's to do with bringing us online with Europe

I'm a main line engineer for EDF mostly working around Hinckley point..

 

[NoobCannon]

Most of the south west is 230-238 hardly ever see 240v any more, apparently it's to do with bringing us online with Europe

I'm a main line engineer for EDF mostly working around Hinckley point..

interesting to see how much it varies across the country.

 

[lewism]

So in end got electrian round. He's changing the ancient CU and installing a pull switch for the shower.

Looks like the old owners got someone in who bodged the job

Including a 100A rcd on a 100A supply which I never noticed

RCD doesn't deal with overload, there's nothing wrong with it.

Interesting, it is firmly over 240 around here in Oxon at idle (although i have only ever had cause to test a few houses). My main house at rest is always over 240, although it is amazing to see the voltage drop when you heavily load the supply (low 220s not uncommon when loaded up).
Interesting that your area differs, i assumed it would be the same nationwide.

Appendix 2 point 15 gives us the +10/-6 tolerance. I've seen it all over the place in in all varieties from 220 all the way up to 250. Probably depends what way the wind is blowing that morning. Which kind of moots the point of a max voltage of 230v in quite a few of the regulations.

I've also had a 10.5kw shower pulling 47amps hold on a 32a breaker for half an hour with not a care in the world. Electricity is a funny old beast and the IET are a safe old bunch. I wouldn't fancy terminating 16mm in to a pull chord anyway.

 

[BigBoy]

. I wouldn't fancy terminating 16mm in to a pull chord anyway.

Why not? 50a rated pull cord are designed to accept large cable sizes.

 

[Jez]

Appendix 2 point 15 gives us the +10/-6 tolerance. I've seen it all over the place in in all varieties from 220 all the way up to 250. Probably depends what way the wind is blowing that morning. Which kind of moots the point of a max voltage of 230v in quite a few of the regulations.

I've also had a 10.5kw shower pulling 47amps hold on a 32a breaker for half an hour with not a care in the world. Electricity is a funny old beast and the IET are a safe old bunch. I wouldn't fancy terminating 16mm in to a pull chord anyway.

Checked this last night out of interest as i had a meter in the house for something else, 244 in Oxon without my house pulling much. Dips heavily if you load the supply though down toward 220 - not sure if this is my supply cable causing voltage drop or the transformer on the pole outside sometimes being very heavily loaded (shared between around 12 houses in my immediate vicinity). Definitely fluctuates a lot, used to be able to tell from the halogen downlights, but those have all but gone now - nothing else notices.

 

[lewism]

Why not? 50a rated pull cord are designed to accept large cable sizes.

A Few Reasons, mostly personal choice,
because it's terrible to fit two 16mms in anything less than a two gang switch. And even then you need at least a 35mm pattress or deep plasterboard box. I'm not saying it can't be done, it's just not how I choose to install my circuits. Very rarely clients want to pay the extra cost for an extra kw of shower power when there are better solutions on the market.

Checked this last night out of interest as i had a meter in the house for something else, 244 in Oxon without my house pulling much. Dips heavily if you load the supply though down toward 220 - not sure if this is my supply cable causing voltage drop or the transformer on the pole outside sometimes being very heavily loaded (shared between around 12 houses in my immediate vicinity). Definitely fluctuates a lot, used to be able to tell from the halogen downlights, but those have all but gone now - nothing else notices.

Like I said, electricity is a funny thing. I'm not well versed on the supply (ESQCR) side of things, but DNOs are generally a law upon themselves.

 

[BigBoy]

A Few Reasons, mostly personal choice,
because it's terrible to fit two 16mms in anything less than a two gang switch. And even then you need at least a 35mm pattress or deep plasterboard box. I'm not saying it can't be done, it's just not how I choose to install my circuits. Very rarely clients want to pay the extra cost for an extra kw of shower power when there are better solutions on the market.

Yeah I totally get that, I work with cable from 10mm² up to 90mm² working with the big stuff in confined spaces is a real pain!

Like I said, electricity is a funny thing. I'm not well versed on the supply (ESQCR) side of things, but DNOs are generally a law upon themselves.

DNO still has to supply a static (semi) value within peramiters, at work I've seen single phase fluctuations from 210-600v (that get scary!).