adapter leads.

[plugwash]

Background.

While wandering around Salford Quays recently I noticed a fat cable coming out of an open manhole behind some temporary barriers. On the end of this cable was a very large IEC60309 coupler (I think it was a 125A three-pase) which was plugged into a distribution box (similar to the stuff that rubberbox sell) which had breakers and a variety of smaller IEC 60309 sockets (I think it was a 63A three-phase, a 32A three phase and three 32A single phase).

Plugged into one of the 32A single phase sockets was an adapter lead with a 32A plug and two 16A sockets. Into one of these sockets was plugged a cable which I believe went off to feed a food van. Presumably the 32A socket was fed by a 32A breaker, so presumably the 16A sockets and cable were not overload protected at source, though there may well have been overload protection in the van.

Which brings me round to my question, are adapter leads like this considered dodgy? or is it considered the user's responsibility to ensure adequate overload protection is in place and/or that overloads are unlikely.

 

[Robin0577]

Simple answer is yes they are.

Problem 1, as you suggest, is the possibility of drawing up to 32A through 1 of the 16A sockets.

Problem 2 is that the security and/or IP rating of the cable gland on the 32A plug is most likely to be compromised by having two cables in it.

Such adapters are in fairly widespread use, and can be safe provided that suitable overload protection is in place and the circumstances do not require the full IP rating to be maintained.


However, there are some circumstances in which an adapter from, say a 32A to single 16A is both acceptable and useful despite the possibility that it could subsequently be used incorrectly and overloaded. Where a very long cable run is needed, it is common practice in temporary installations to use, say 32A extension cables for a 16A circuit, with 16>32 and 32>16 adapters at the ends in order to achieve acceptable voltage drop.

P.S. For full details, see the snappily titled, riveting read that is "BS7909:2011 - Code of practice for temporary electrical systems for entertainment and related purposes"

 

[JohnW2]

Plugged into one of the 32A three phase sockets was an adapter lead with a 32A plug and two 16A sockets. .... Which brings me round to my question, are adapter leads like this considered dodgy? or is it considered the user's responsibility to ensure adequate overload protection is in place and/or that overloads are unlikely.

Interesting question - and I'll be interested to hear what people have to say.

If one believes that overload protection is only there to protect the cable (rather than also the load), I suppose that the only thing that would matter would be that the cable connecting the 16A sockets to the 13A plug would be adequately protected by a 32A breaker - did it look as if that might be the case?

More generally, I suppose the same conceptual issue arises with 13A BS1363 plugs plugged into sockets or extension leads - and in that case it clearly is regarded as "the user's responsibility" to ensure that an appropriate fuse is put in the plug.

Kind Regards, John

 

[Robin0577]

As John points out, it does all come down to responsibility. In my previous job, working for a lighting & sound company, I refused to make up such cables for sale or hire to customers because the issue of the compromised cable gland effectively prevented them from passing the visual inspection part of a PAT.

 

[JohnW2]

As John points out, it does all come down to responsibility. In my previous job, working for a lighting & sound company, I refused to make up such cables for sale or hire to customers because the issue of the compromised cable gland effectively prevented them from passing the visual inspection part of a PAT.

That's obviously a rather different matter (different from considerations of possible overload). As a matter of interest, would you still have refused to make up such cables if some sort of gland had been available that was designed for two separate cables (or if the 'splitting' had occurred in some other item/enclosure which had glanding appropriate to the cables)?

Kind Regards, John

 

[Robin0577]

Good question. I must admit to using that as a solid reason to avoid doing it, thus avoiding the need to deal with the rather more grey question. I think probably I would have made them up, on the grounds that such an item would be safe if used correctly.

 

[JohnW2]

Good question. I must admit to using that as a solid reason to avoid doing it, thus avoiding the need to deal with the rather more grey question. I think probably I would have made them up, on the grounds that such an item would be safe if used correctly.

Fair enough. Per what I suggested before, I suppose it's conceptually similar to selling an item which is fitted with a cable and BS1363 plug, the cable not be up to 13A, but the fuse in the plug being appropriate for the supplied cable. There must be countless items like that being sold, and the manufacturer/selling is relying on the buyer not swapping the fuse for a 13A one!

Kind Regards, John