13A and 16A sockets on the same 20A radial. OK or not?

[Mark42]

I’ve just had a ‘robust exchange of views’ with a visiting engineer about the 16A sockets in my workshop. These, together with local 13A sockets, are run from radials in 2.5mm, protected by 20A RCBOs.

I say it’s fine to have say a couple of 16A interlocked sockets, and lots of 13A doubles on each radial.

See pictures below: All the sockets in each picture are on the same individual radial (Ignore the 3P socket and the drill supply).

The visitor insisted you must have a separate circuit for 16A sockets, protected at 16A.

I say that’s rubbish, as the protection in this case is rated to the cable CCA and length, and 20A max is fine for 16A sockets as 16A plugs are not fitted to equipment which draws more than this.

All is under the supervision of trained personnel. Care is taken with load balancing as the supply in this remote building is limited to 20A per phase anyway.

Who is right?

 

[davesparks]

There are 13 Amp sso involved 4mm2 32 Amp no worries, wire the 16Amp sso on their own 20Amp OCPD

Your post certainly didn't make that clear.

So what you're suggesting here is to remove this perfectly compliant installation and install new circuits?

 

[Pete999]

Your post certainly didn't make that clear.

So what you're suggesting here is to remove this perfectly compliant installation and install new circuits?

Yep I am 4mm2 for the 13Aand 2.5 for 16A 32 and 20 OCPDs respectively

 

[radiohead]

Yep I am 4mm2 for the 13Aand 2.5 for 16A 32 and 20 OCPDs respectively

What would be the advantage over an already compliant circuit which is apparently in service without issue?
Explain please.

 

[Mark42]

... My biggest concern is how clean and tidy that workshop is, that can't be healthy.

Ha Ha! It was not always thus.

Now I'm semi-retired I rent the workshop out as a sideline. So it has to be nice and tidy, to aerospace/military standards: Mop the floor, polish the bloody sockets, clean the tops of the doors and so on ...

I used to have six work tables, all of which gradually got covered with works-in-progress in a total mess and there was never anywhere to put anything down. So to solve this, I didn't get rid of the works-in-progress, I got rid of the tables. Reduced to two. So I now have to put stuff away properly, in nicely-labelled boxes in the tool room.

Which means, of course, that I can no longer find anything!

 

[davesparks]

Yep I am 4mm2 for the 13Aand 2.5 for 16A 32 and 20 OCPDs respectively

But why? It is fully compliant and safe now, to suggest replacing the installation for no valid reason is just ridiculous

 

[Pete999]

What would be the advantage over an already compliant circuit which is apparently in service without issue?
Explain please.

I don't believe that how it is wired now makes it a standard final circuit as [er BS 7671, that's my opinion. like you Davesparks disagrees with me. that's OL we all have our opinions.

 

[radiohead]

I don't believe that how it is wired now makes it a standard final circuit as [er BS 7671, that's my opinion. like you Davesparks disagrees with me. that's OL we all have our opinions.

An indication of where the trade has gone wrong, sharp intake of breath, shake of the head, no engineering judgement. Got a box to tick so it'll have to be ripped out and rewired Sir.
Just my opinion.

 

[Pete999]

An indication of where the trade has gone wrong, sharp intake of breath, shake of the head, no engineering judgement. Got a box to tick so it'll have to be ripped out and rewired Sir.
Just my opinion.

I judge it as wrong Mate

An indication of where the trade has gone wrong, sharp intake of breath, shake of the head, no engineering judgement. Got a box to tick so it'll have to be ripped out and rewired Sir.
Just my opinion.

Go for it!

 

[radiohead]

If I was installing it I'd do the same as you, 13a outlets either on a ring or radial, each 16a outlet on a dedicated 16a radial. But it seems pointless to change an existing installation which is compliant and working satisfactorily, really for no other reason than to tick an..... 'its not how I would do it' box.

 

[westward10]

I would say it is more unconventional as opposed to non compliant. If it were a 30/32A ring final I would suggest the 16A socket outlets should not be protected by such a device. As it stands there is no real issue.

 

[davesparks]

I don't believe that how it is wired now makes it a standard final circuit as [er BS 7671, that's my opinion. like you Davesparks disagrees with me. that's OL we all have our opinions.

No it isn't a 'standard final circuit' as far as it doesn't match the pretty pictures in the idiots guide exactly, But there is absolutely nothing in the regulations requiring anyone to follow the 'standard circuits'.
The regulations tell us the rules for designing circuits and give us the option of using the standard socket circuits if we wish to, there is nothing saying they must be followed.

Electricians are supposed to be technically competent people capable of designing circuits to suit an application and not just blindly follow pictures in a book.

There are no standard circuits for appliance supplies, lighting circuits or anything other than ring or radial socket circuits.