Spur from cooker supply

[Callumh1992]

Good Evening. I’m currently carrying out an EICR. I have a cooker circuit radial with a 32amp mcb fed from and RCD split board. There is a 45amp double pole switch fitted with a single socket on the plate. Fed in 6mm T+E.

Then there is a 2.5mm T+E off the load side of the cooker switch down to a single 13Amp switched socket.

My question is will this be within regs? Probably not the best practice I know but just want others opinion. As far as I understand it would be ok as the most current going along the 2.5mm would be 13amps?

Look forward to your opinions.

 

[timhoward]

It's quite common to see this coming out of a cooker plate to serve hob ignition.
If it's clipped and <3m long I've generally taken the view 433.2.2 ii) covers this scenario.

However, if there is no cooker/oven, just a single 13amp socket on switch and another one on the load side, would it not be simpler to just advise changing the MCB to 16 amps?

 

[Callumh1992]

It's quite common to see this coming out of a cooker plate to serve hob ignition.
If it's clipped and <3m long I've generally taken the view 433.2.2 ii) covers this scenario.

However, if there is no cooker/oven, just a single 13amp socket on switch and another one on the load side, would it not be simpler to just advise changing the MCB to 16 amps?

Hi. Unfortunately the cookers is connected to it

 

[James]

Good Evening. I’m currently carrying out an EICR. I have a cooker circuit radial with a 32amp mcb fed from and RCD split board. There is a 45amp double pole switch fitted with a single socket on the plate. Fed in 6mm T+E.

Then there is a 2.5mm T+E off the load side of the cooker switch down to a single 13Amp switched socket.

My question is will this be within regs? Probably not the best practice I know but just want others opinion. As far as I understand it would be ok as the most current going along the 2.5mm would be 13amps?

Look forward to your opinions.

Flip your thinking around, can you think of a reg that it contravenes?

 

[Callumh1992]

Flip your thinking around, can you think of a reg that it contravenes?

I’m hopeless with regs. That’s why I’m looking for advice?

 

[James]

errmm, why are you doing an EICR?

understanding the regulations is in my opinion one of the most important skills required to do electrical inspections.
installation is fine, you can generally focus on the regs that apply to the type of installation work you carry out.

but to inspect something you should have a better understanding than "I’m hopeless with regs."

Spend some time bringing your knowledge and skill level up, it is good to learn.

 

[timhoward]

I’m hopeless with regs. That’s why I’m looking for advice?

An interesting statement given what you are trying to do!
I'm trying to help you here.... you had an inkling there is something not quite right about this. You are actually right. What was it that made you think "hang on"?

 

[Callumh1992]

errmm, why are you doing an EICR?

understanding the regulations is in my opinion one of the most important skills required to do electrical inspections.
installation is fine, you can generall focus on the regs that apply to the type of installation work you carry out.

but to inspect something you should have a better understanding than "I’m hopeless with regs."

Spend some time bringing your knowledge and skill level up, it is good to learn.

An interesting statement given what you are trying to do!
I'm trying to help you here.... you had an inkling there is something not quite right about this. You are actually right. What was it that made you think "hang on"?

The change in cable size got me thinking. But I know there is a Reg about length of cables for tails etc. so thought I’d check.

 

[Callumh1992]

errmm, why are you doing an EICR?

understanding the regulations is in my opinion one of the most important skills required to do electrical inspections.
installation is fine, you can generally focus on the regs that apply to the type of installation work you carry out.

but to inspect something you should have a better understanding than "I’m hopeless with regs."

Spend some time bringing your knowledge and skill level up, it is good to learn.

I’m carrying out an EICR because it’s part of my Job as an approved electrician. It’s not that I’m hopeless I know a lot but there’s a lot I don’t. Part of learning I guess.

 

[James]

perhaps, i over reacted.
it was the quote

I’m hopeless with regs. That’s why I’m looking for advice?

left me a bit stunned.
I hope that the above statement is not actually correct.

 

[timhoward]

The change in cable size got me thinking.

So the general rule is that the current carrying capacity of the cable will exceed the protective device (32 amps) in
normal cases. 6 sq mm will normally carry 32 amps. 2.5 sq mm won't.
So the correct alarm bell went off.

We're therefore looking for exceptions to this rule.
I've believed (and maybe I'm about to be shot down myself!) that the reg I posted above regarding overload protection, and the similar one for fault protection could be applied to the situation where there's a cable that no-one can get to, if adequately secured, and there was a further protective device within 3m.

 

[Callumh1992]

So the general rule is that the current carrying capacity of the cable will exceed the protective device (32 amps) in
normal cases. 6 sq mm will normally carry 32 amps. 2.5 sq mm won't.
So the correct alarm bell went off.

We're therefore looking for exceptions to this rule.
I've believed (and maybe I'm about to be shot down myself!) that the reg I posted above regarding overload protection, and the similar one for fault protection could be applied to the situation where there's a cable that no-one can get to, if adequately secured, and there was a further protective device within 3m.

Ok so the cable is clipped to the posts running about 1.5m from the cooker switch down to the 13a switched socket. I’m assuming the 13a plug top counts and a protective device or would I change to a spur?

 

[James]

So the general rule is that the current carrying capacity of the cable will exceed the protective device (32 amps) in
normal cases. 6 sq mm will normally carry 32 amps. 2.5 sq mm won't.
So the correct alarm bell went off.

We're therefore looking for exceptions to this rule.
I've believed (and maybe I'm about to be shot down myself!) that the reg I posted above regarding overload protection, and the similar one for fault protection could be applied to the situation where there's a cable that no-one can get to, if adequately secured, and there was a further protective device within 3m.

I agree, if it was not possible to feed a socket from 2.5mm (single run) from a circuit spurred off or joined to a 32A distribution circuit or similar then 90% of homes and businesses would fail on that point.

lets face it, a spur from a ring has similar protective devices and a single 6mm cable is similar to 2 x 2.5mm run in a ring or parallel.
overload is obviously sorted by the fuse in the plug so we are only looking at fault protection anyway.

 

[James]

There is a huge difference between

comparing an instalation to what is considered best practice and trying to figure out how to code things that dont match up

to

understanding the science behind the regs and applying them with a level head to ensure the installation is actually safe, ensuring that failures are noted correctly.

 

[Pretty Mouth]

I would put this down to 433.3.1(ii) - no overload protection needed because the load at the single socket can't overload the cable, being fused at 13A. The 32A protective device should deal with fault current.

But actually, this arrangement is shown in appendix 15, figure 15B on p556 - a 4mm radial on a 32A, with a twin socket spurred in 2.5mm. If diversity says it's okay (which in my experience it usually does) then all good

I’m hopeless with regs.

They're not easy reading it has to be said, but persevere, you'll get to understand them better if you keep at it. I recommend reading chapter 43 - protection against overcurrent on p92. It's only about 8 pages long and covers this subject. Just ask if you have trouble understanding, we'll help you out. Also appendix 15 p555.