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

 

[telectrix]

assuming the cable is 2.5mm (or greater) then a 20A MCB is fine to protect the cable. as it's a dedicated load incapable of overloading the 16A socket, then i can't see a problem.

 

[Andy78]

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

Who has coded it a C2 issue ?
Have they quoted a regulation that it does not comply with ?

 

[westward10]

You can use 20A to supply 16A sockets but I would only do this if the circuit supplied more than one. If it is one socket I would not use 20A.

 

[David Rann]

I have gone back with page 184 on IET on site guide 20 amp maximum. It's 2.5mm over 10 meters. I don't know who has gave it a c2 as this is coming from the customer I did the job for 18 months ago.

 

[David Rann]

Why is this?

 

[David Rann]

You can use 20A to supply 16A sockets but I would only do this if the circuit supplied more than one. If it is one socket I would not use 20A.

Why is this? Can you show me a regulation number? Cheers

 

[telectrix]

then get the customer to enquire as to the specific regulation that applies to this C2.

 

[westward10]

Why is this? Can you show me a regulation number? Cheers

No but I do not see the sense in putting a single 16A socket on a 20A protective device.

 

[David Rann]

I have gone back and asked him for reg number. This was a few days ago. Still not heard anything.

 

[David Rann]

No but I do not see the sense in putting a single 16A socket on a 20A protective device.

Because it's an ev charger and like I said in the original post charges for 16 amps constant. Over time I have had them wear the bi metallic strip and start to trip. 20 amps takes the stress off and complies with IET on site guide.

 

[telectrix]

I have gone back and asked him for reg number. This was a few days ago. Still not heard anything.

because there isn't one.

 

[David Rann]

Well I will wait and see what they come back with. Part of me thinks they are on a ....that needs changing we can do it now for £200

 

[westward10]

Sounds like the 16A socket is not big enough.

 

[David Rann]

Sounds like the 16A socket is not big enough.

Possibly but never had an issue with the commandos only the breakers.

My point being if you are going to C2 something you need to back it up with a regulation otherwise it's just an opinion?

Cheers

 

[westward10]

I wouldn't Code it at all but if a 16A device trips then it is inadequate for the connected load and this must also apply to the 16A socket, change it to a 32A socket.

 

[David Rann]

Can't change it to a 32amp as it's a fixed adapter with electronics inside.

 

[telectrix]

if the charger is designed to plug into a 16A socket, then the 16A socket is sufficient.

going by the argument of whoever coded it, that means we need to fit 13A socket circuits with a 13A MCB.

 

[Simlec]

20 amp should be fine supplying your 16amp socket as you say its covered in OSG part H3.
Out of interest have you hit mainly drains installing your earth rods for your EV chargers ?

 

[David Rann]

20 amp should be fine supplying your 16amp socket as you say its covered in OSG part H3.
Out of interest have you hit mainly drains installing your earth rods for your EV chargers ?

I don't know! Scary every time though. Bought a cat scanner for cables but still!! 18th edition takes out the "where reasonably practical" bit. So expect a lot of People hitting utilities

 

[David Rann]

16 amp commando and the osg.

 

[Simlec]

lol, I was expecting to see lots of pic's online of earth rod explosions and like but nothing yet (that I have seen) but I feel its coming.

 

[David Rann]

lol, I was expecting to see lots of pic's online of earth rod explosions and like but nothing yet (that I have seen) but I feel its coming.

I need to make sure my public liability covers it!

 

[davesparks]

Because it's an ev charger and like I said in the original post charges for 16 amps constant. Over time I have had them wear the bi metallic strip and start to trip. 20 amps takes the stress off and complies with IET on site guide.

This suggests it is either a poor choice of MCB or actually pulling more than 16A.

A single 16A socket shouldn't need to have an ocpd of more than 16A supplying it, if it does then it is most likely overloaded.

 

[David Rann]

This suggests it is either a poor choice of MCB or actually pulling more than 16A.

A single 16A socket shouldn't need to have an ocpd of more than 16A supplying it, if it does then it is most likely overloaded.

Would you C2 it though?

 

[Ian1981]

Stick a clamp meter on the circuit to see how many amps it's pulling

 

[David Rann]

No point...this is about someone coding a c2 contradicting the IET

 

[Ian1981]

delete

 

[Simlec]

What does he need to clamp it for? He has designed it correctly and no parts are in danger .
No code and I don’t see how you can code it.

 

[Deleted account]

An EICR is only to test and inspect the electrical installation. Not the equipment/ appliances plugged into it. If an appliance is over loading the 16a commando socket then that is an issue with the appliance, not the installation.

 

[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