Using a 16A appliance in a 13A socket?

[JP Coetzee]

Ah OK. The reas> The compact socket looks like the following (joint the link back up in notepad): >

socket?

[TheOldFellow]

Yes, as you say. I learned something today too. I have to fit one for my planer (16A) R.

[Dave Plowman (News)]

Will you actually have to unplug the kiln that often? And since you said it has integral switching no need to worry about arcing. So why bother with a switched type? The CU is presumably nearby if you did need to isolate things quickly for any reason.

[Dave Osborne]

Have to agree with you on this one Andy.

IME, most workshops are wired so that each "machine position" has it's own radial circuit. There is usually only a 13A ring main for a bunch of

13A socket outlets for light-bench top use and then, if there are multiple benches, each one often has its own radial circuit with a local RCD.

Notwithstanding whether it's allowed on the 17th, I would be inclined to install a 20A radial circuit (i.e min 2.5mm2 cable) with a 16A MCB dedicated for this equipment.

OK, I've checked the 17th OSG and Appendix 8 Sec 8.3 allows for a radial final circuit using a 16A socket-outlet complying with BS EN 60309-2 (BS

4343).

The use of an interlocked socket outlet is *not* prescribed. The use of a switched socket outlet is *not* prescribed.

However, according to Appendix 10 of the OSG, whilst an IEC 309 connector is good for isolation and functional switching (by virtue of pulling the plug), it is not good for emergency switching, so really, there should be an isolating switch adjacent to or incorporated with the socket outlet.

Having allowed for diversity (none in this case) a 20A radial circuit is acceptable, in which case, the number of sockets is unlimited.

Minimum conductor size is 2.5/1.5 mm2 (Table 8A). Table 7.1 and Appendix

6 apply for grouping/derating.

[Dave Osborne]

Not so, according to OSG Appendix 8. BS4343 socket outlets are allowed and interlocking/shuttering is not prescribed.

[js.b1]

Yes, you pull it forward or push it back.

- It will not turn ON unless a plug is in (paperclip safe)

- It will not allow a plug to be removed unless turned OFF (flash safe)

If you search on that GW66xxxx part number you should get a website showing the dimensions - it is not huge, not small. It is smaller than the MK Commando version which is an extremely large "wedge shaped block of grey cheese".

The dedicated 16A circuit breaker is required because the 16A plug has no fuse :-) Contrast with your 32A ring final circuit which has 13A fused plugs, obviously you can not connect anything 16A to a 13A fuse (plug, spur) because it will blow the fuse within a few minutes as well as cause overheating.

[Dave Osborne]

No, an interlocked socket has a socket with an adjacent switch which are mechanically interlinked.

That is to say:

1. If there is no plug in the socket, the switch can not be turned to the on position.
2. If the switch is on, then the plug can not be removed from the socket.

This is good because, with this arrangement:

1. You can not connect or disconnect the plug under load.
2. The socket outlet can not be live if there is no plug inserted. This gives the same effect as shuttered 13A socket outlets (i.e. protects from prying fingers).

[Dave Osborne]

Such a solution would not (IMO) comply with regulation 537.4.2.5 which effectively requires emergency switching at the socket outlet as table

53.2 does not allow the use of an IEC309 connector for emergency switching.

[Frank Erskine]

No - it's a switched socket. Switching it on mechanically (at least on the ones I've seen) locks the plug to prevent it being withdrawn. The same mechanism prevents you from switching on unless there's a plug in.

[JP Coetzee]

The missus likes to turn the kiln off at the wall. That's pretty wise in a wooden shed.

*waits for questions about fire security*

That switched outlet is pretty compact, and angled downward so the cable will be out of the way. I like it.

[Tim Watts]

Scrump wibbled on Wednesday 03 February 2010 13:35

I mentioned a few posts back:

If the plug is out, you cannot move the switch to "On";

If the plug is in, you can now switch On;

Once "On", you cannot withdraw the plug (which is good also as it prevents any possibility of the plug being half out and making bad contact and getting hot.

Downside, is you can't yank the plug out by the flex in an emergency (but you generally cannot with commandos as on the other non-interlocked versions, the lid retains the plug). So the machine, if dangerous, should have suitable emergency stop button(s) or isolators, but I guess they mostly do...

Beware - these can be stupidly expensive until you google around, then you can get them for sensible money.

[Tim Watts]

Scrump wibbled on Wednesday 03 February 2010 13:56

No, you turn the switch off at the socket (it's integrated).

See here:

fact, that is one of the more sensible prices you will see...

Another thing that is useful, is you can often put a padlock through the isolator to prevent anyone else turning it on when you don't want them to.

[Tim Watts]

JP Coetzee wibbled on Wednesday 03 February 2010 12:33

They exist:

that's silly money... Look around, the same part should be available from somewhere for rather less...

[Tim Watts]

Dave Osborne wibbled on Wednesday 03 February 2010 15:08

Reg 553.1.4: "Every socket outlet for household and similar use shall be of the shuttered type, and for an AC installation, shall preferably be of a type complying with BS1363."

As I said, I wouldn't get too hung up for a workshop, but the intention is clear - stop kiddies sticking things in...

Interlocking is the best way IMHO to achieve the spirit, but ensuring either unreachable sockets or a locked workshop would be other ways.

It's worth bearing in mind what happens if you sell the house - the next person may not be so clueful.

[Dave Osborne]

OK.

Agreed.

Agreed.

However, unfortunately, "unreachable sockets" are generally proscribed and in this case would likely break one or more provisions of Reg 537 (Isolation and Switching) e.g. 537.4.2.5 "The means of operation shall be readily accessible...".

Also, not so much a locked workshop, but a padlocked isolating switch would be in order again as per various provisions of Reg 537.

===

OK, the Regs and the OSG are at odds then.

In the Regs it hinges on the interpretation of "household and similar use".

Reg. 553.1.3 allows for IEC309 connectors for low voltage circuits, but

Reg. 553.1.4 then effectively precludes them for "household and similar use" because they are not shuttered.

However, the OSG recognises IEC309 connectors on a 16A radial circuit as a standard circuit arrangement for household and similar use, but does not prescribe interlocking in lieu of shuttering.

Section 20 of the Regs does not define shuttering and the word is not indexed either, so unless someone can point to a regulation (or BS) where shuttering is further defined, we would have to fall back on regulation 120.3 and make the argument that interlocking is just as safe as shuttering and may be implemented in lieu with impunity.

Cheers, DaveyOZ

[Harry Bloomfield]

You need to add another breaker rated 16amp and wire from that to a dedicated 16amp socket and fit a 16amp plug (like that of your URL, but a plug rather than the socket shown) to the kiln. The 16amp with an attached 13amp (in the URL) is to enable a caravan to be plugged in to the mains at home.

[Andrew Gabriel]

I've no idea what the warm-up period and duty cycle are, but you could well be right. This is not the case for a domestic oven though, as warm-up is usually quite quick, and then the duty cycle is low.

[Andrew Gabriel]

There is no requirement for emergency switching though. If you're leaning on the kiln and getting burned, disconnecting the supply quickly isn't going to make any difference. That's not to say that having a switch isn't sensible, but it would be for functional switching, not emergency switching.

[David Hansen]

On Wed, 03 Feb 2010 16:47:12 +0000 someone who may be Dave Osborne wrote this:-

I would just list the sockets as an exception, something provided for in the forms and regulations, and argue the case in court if it came to that.

[David Hansen]

On Wed, 3 Feb 2010 17:48:41 +0000 (UTC) someone who may be [e-mail] (Andrew Gabriel) wrote this:-

I imagine that a kiln is a fairly steady load, I would consider it to be at least as steady as an immersion heater, probably more steady. However, that doesn't matter if the ring circuit is otherwise lightly loaded, give it some work to do for once.

Given the spare way in this case it makes sense to wire a socket to that in most cases. However, in other circumstances, if the ring only powers a few hand tools, connecting the kiln will not be a problem.