16 amp commando sockets. 20 amp mcb on site guide as maximum value mcb

[David Rann]

Hello the on site guide lists 20 amp maximum mcb for 16 amps sockets. Having a debate with someone as to why this is? Why not 16amp mcb? I installed 20 amp mcb as it's for a car charger that charger's at 16amps for 8 hours and is not capable of pulling more than 16 amps but this has been pulled as a C2. I didn't install 16amp as have in the past and over time the bi metallic strip has worn and started to trip after 12 months or so.

Cheers

 

[Ian1981]

The clamp meter was out of interest but thanks for clearing up the scope of what an eicr covers because really I had no clue!

 

[David Rann]

An eicr is a report on the condition of an installation. It's your opinions backed up by regulations. If you C1 or C2 it then you have to have a reg number to back it up. You can't just go in and say in my opinion....

 

[Ian1981]

You do not need to state the regulation number on a eicr but yes the code does have to relate to something meaningful in the regulations that gives rise to possible danger and safety issues of the existing installation

 

[David Rann]

You do not need to state the regulation number on a eicr but yes the code does have to relate to something meaningful in the regulations that gives rise to possible danger and safety issues of the existing installation

Yes you don't need to write the reg next to it but if somebody questions it you need to be able to back it up.

 

[Ian1981]

It would seam he has fallen into the trap of Ib<In<Iz which is really only applicable if overload is a factor.
As this is a fixed load then he can't code it based on this alone.

 

[telectrix]

It would seam he has fallen into the trap of Ib<In<Iz which is really only applicable if overload is a factor.
As this is a fixed load then he can't code it based on this alone.

but Iz is the current capacity of the cable, not related to the socket.

 

[David Rann]

Exactly 433.3.1 (ii) since the car can pull no more than 16amps then overload protection need not apply only fault protection.

 

[Ian1981]

but Iz is the current capacity of the cable, not related to the socket.

Yeah but perhaps he's thinking of the flex that plugs into the socket if it's only 1.5mm2
Just trying to understand why it's coded
Nothing to do with the fixed wiring but it's maybes why?

 

[telectrix]

the flex on an appliance does not come within the remit of BS7671.

 

[Wilko]

From afar, I feel I would not have coded it at all. Can it be less than safe, given it's the OSG advice on p184 ?
Good discussion of design

 

[David Rann]

From afar, I feel I would not have coded it at all. Can it be less than safe, given it's the OSG advice on p184 ?
Good discussion of design

Exactly and when I question what reg they are coding it under I've heard nothing?

 

[Ian1981]

Because he can't give a definitive answer I would guess.
Maybe he realises he's had a nightmare

 

[telectrix]

Exactly and when I question what reg they are coding it under I've heard nothing?

regulation 000.00.000. thou shalt not code anything that does not contravene any of the other regulations that we, the all knowing, all seeing, IET, want to dream up to make electricians lives more difficult than we have already made them. ..........


......... excuse the break. amendments to the 18th neeed to be drafted.

these will, of course incur charges at you normal rates.

 

[davesparks]

It would seam he has fallen into the trap of Ib<In<Iz which is really only applicable if overload is a factor.
As this is a fixed load then he can't code it based on this alone.

It's a bit of a stretch to call a socket outlet a fixed load isn't it?

And the fact that when connected via a 16A mcb it trips on overload it suggests that the 16A socket is overloaded.

 

[Ian1981]

I've lost track dave, I thought this thread was about coding something incorrectly, then it's went to overloaded 16 amp socket.

 

[David Rann]

I've lost track dave, I thought this thread was about coding something incorrectly, then it's went to overloaded 16 amp socket.

It is! It's about coding something c2 when the iet clearly states it's okay! Nothing is tripping out?

 

[davesparks]

I've lost track dave, I thought this thread was about coding something incorrectly, then it's went to overloaded 16 amp socket.

It started out that way, but then the OP revealed that the reason he fitted a 20A ocpd was that the load causes a 16A ocpd to trip on overload.

 

[David Rann]

I've lost track dave, I thought this thread was about coding something incorrectly, then it's went to overloaded 16 amp socket.

It is! It's about coding something c2 when the iet clearly states it's okay! Nothing is tripping out?

 

[westward10]

BS7671 makes absolutely no reference as to the minimum or maximum protective devices for EN60309 sockets.

 

[David Rann]

No I said I have known over time for this to happen...20 amp mcb just takes the stress off

 

[David Rann]

So the point of reference is iet osg p184.

 

[westward10]

I would not use the OSG whilst doing an EICR.

 

[David Rann]

I don't do eicrs

 

[Richard Burns]

You have had your work queried during a subsequent inspection.
You know that the situation is not contravening the wiring regulations and the inspector cannot provide a regulation to match the C2 coding.
Advise the customer of this and finish the discussion.
Unless anything further comes up there is nothing to pursue.

You can consider the merits of the comparison of the protective device and the rating of an accessory but that is not really an issue in this case despite what you have mentioned about the loading and MCB operation. So long as the socket is not taking more than 16A then there is no problem.

 

[David Rann]

Always good to a few opinions because I've never had my work questioned subsequently by another electrician.

 

[David Rann]

Thanks for your input everyone. Great forum.

 

[bigspark17]

the flex on an appliance does not come within the remit of BS7671.

What about a storage heater or an immersion tank?

 

[jumpin212]

Would reg 722.411.4.1 be a possibility for the c2

 

[David Rann]

Can you state it?

 

[Deleted account]

What about a storage heater or an immersion tank?

Not wanting to put words in teletrix 's mouth but I think he meant flex on portable appliances as is the case in this thread.