Arctic or HO7RN-F extension lead?

[EightyTwo]

Quick question: I'm intending to run a summer house from a 4mm extension lead that will be run out when her shed is in use. I'll be using IP67 32A "Commando"-type plugs and sockets. Would you go for blue arctic cable or black HO7RN-F cable? The rubber is marginally lighter in weight but with a thicker diameter than the slightly cheaper PVC. We'll be winding the cable up when not in use but it might stay out for a few weeks in the summer.

What are your thoughts?

 

[oldbutnotdead]

What length is the cable run? What sort of switchgear is on the supplying circuit? What load are you planning?
I'd go the rubber myself (it'll coil better after being trampled in the mud for weeks) but if this summerhouse is a permanent feature you'd be much better off putting a permanent SWA feed in. While you're digging the trench you can chuck some duct in for ethernet, coax, alarm cabling, anything else that comes to mind

 

[EightyTwo]

It's going to be 20-30m long from the end of an outbuilding (with its own CU and RCD) to the summerhouse. The load coud be anything 50W to 5000W depending on whether she's charging a phone or running a heater. Burying SWA was my original thought but it's too much work for temporary use (probably a couple of dozen times a year...) and there's a concrete path and old cesspit to get past. If I had my way, she'd be using batteries and/or our normal extension lead! I thought that this "turbo" extension lead idea was a good halfway house (and I've seen it used on shipping containers and Portacabins). I'll be putting a CU in the shed, on the end of the Commando plug mounted outside. Thanks for your input @oldbutnotdead

 

[JohnW2]

... I'll be putting a CU in the shed, on the end of the Commando plug mounted outside.

If (as it sounds to be the case) you will just want some lighting and a socket or three, then you don't really need a CU - the sockets could be fed directly from the incoming supply, and the lights fed via a 3A FCU from the supply.

Kind Regards, John

 

[EightyTwo]

Good point John but I'd feel happier with another RCD and a couple of MCBs in case someone wants to plug in a hedge trimmer or something. The CU also acts as a convenient JB and an isolator inside the shed and, in the grand scheme of things, doesn't cost that much more.

 

[plugwash]

My concern with such a setup is that as much as you and your wife tell yourselves you will unplug it when not in use, in reality you won't. Then over the years it will get trampled into the ground/hidden in the undergrowth and not be visible. Then years later someone will put a spade through it or the insulation will fail in the places that get trampled most frequently.

 

[flameport]

We'll be winding the cable up

That won't happen, and blue 32A sockets are not appropriate for domestic use.

 

[EightyTwo]

... and blue 32A sockets are not appropriate for domestic use.

Huh? What does that mean? Are they only suitable for caravan and boat owners, people who work in data centre comms rooms and building site labourers?!

 

[JohnW2]

Good point John but I'd feel happier with another RCD ....

Other than for 'redundancy (in case the upstream RCD becomes faulty), there is nothing to be gained by having a second RCD protecting the same supply./circuit(s). In the event of a fault in the summerhouse, it would be pot luck as to whether one, the other or both RCDs operated.,

... and a couple of MCBs in case someone wants to plug in a hedge trimmer or something.

I'm not quite sure what you mean by that.

The CU also acts as a convenient JB and an isolator inside the shed and, in the grand scheme of things, doesn't cost that much more.

Largely true, but a downside of installing a CU is that such is 'notifiable' work, which means that (if you want to stay on the right side of the law) DIYng it would almost certainly not be cost-effective Mind you, if the whole setup is going to be a 'new circuit', originating at the CU in the other outbuilding, the whole exercise would be notifiable, invoking the same issue of cost-effectiveness (or not) of DIY.

Kind Regards, John

 

[plugwash]

Huh? What does that mean? Are they only suitable for caravan and boat owners, people who work in data centre comms rooms and building site labourers?!

I presume he is referring to the fact that BS7671 says that sockets for domestic purposes should be shuttered, I'm not sure it's defined anywhere exactly what is meant by shuttered and whether the sprung flaps on IEC 60309 sockets can be counted as a shutter.
.

 

[JohnW2]

I presume he is referring to the fact that BS7671 says that sockets for domestic purposes should be shuttered, I'm not sure it's defined anywhere exactly what is meant by shuttered and whether the sprung flaps on IEC 60309 sockets can be counted as a shutter. .

I don't think 'shuttered' is defined anywhere in BS7671, but I would doubt that the intent/spirt was that the 'spruing flap' of a 60309 one would count.

The regs seem pretty clear in saying that domestic ("household and similar use") sockets must be shuttered. Mind you, there are ones with 'interlocks' which render them safe when there's not a plug in them, aren't there? - if so, even if not literally 'shuttred', they would seem to be within the spirit of 553.1.201, wouldn't they?

Kind Regards, John

 

[oldbutnotdead]

Don't think you can get an interlocked trailing socket though....
@EightyTwo yes digging a 30m long trench will be a bore but you'll only be doing it once. 30m of 4mm 3 core flex is quite a big heavy cumbersome lump, you will very quickly get bored of coiling it up and storing it somewhere safe.

 

[JohnW2]

Don't think you can get an interlocked trailing socket though....

I think it's probably a ('male') 'power inlet' attached to the building that were talking about ..

.... I'll be putting a CU in the shed, on the end of the Commando plug mounted outside.

... which presumably means that the need for shuttering/interlocking/whatever would relate to the trailing ('female') whatever-one calls-it - and, as you imply, such an animal may well not exist.

Kind Regards, John

 

[plugwash]

Don't think you can get an interlocked trailing socket though....

Lewden seem to make them in 16A and 32A and a variety of voltage/pole configurations.

https://www.lewden.com/media/docs/catalogo-xcee-0919.pdf

Page 16.

Actually buying them seems like it might be difficult and expensive though.

 

[EightyTwo]

I think I'll go for the rubber - it might be more UV stable and flexible than the PVCÒ and it will mostly be out in the summer. I reckon it'll probably weigh around 15kg.

Thanks for all the warnings about (not) rule-following. Duely noted (but this post was about the type of cable).