Sockets used for out door equipment who is responsible for safety?

ericmark · 7 Jun 2021

If I give an example, where I work we have the blue 16 amp sockets for powering the yellow bricks when working outside, these are also used during events for anything from the steam organ to volunteers caravan.

Likely all RCD protected, but not so sure of supply type, it could well be TN-C-S.

I would guess the yellow brick connects the input earth to output earth? Seen no provision for connecting an earth rod, and even inside the buildings some have steel rails which extend for 8 miles outside the building, not looked to see if bonded, but not seen any bonding.

Of late increased use of caravans and the like, with sockets being used for their supply, although not fitted with that in mind.

If the PEN was lost and rails are earthed likely no real danger, may get some sparks when changing the points, but the question is should the PEN be lost and it is a TN-C-S supply who is at fault, the person who plugs into the supply, or the person who fitted the socket?

SUNRAY · 7 Jun 2021

ericmark said:
If I give an example, where I work we have the blue 16 amp sockets for powering the yellow bricks when working outside, these are also used during events for anything from the steam organ to volunteers caravan.

Likely all RCD protected, but not so sure of supply type, it could well be TN-C-S.

I would guess the yellow brick connects the input earth to output earth? Seen no provision for connecting an earth rod, and even inside the buildings some have steel rails which extend for 8 miles outside the building, not looked to see if bonded, but not seen any bonding.

Of late increased use of caravans and the like, with sockets being used for their supply, although not fitted with that in mind.

If the PEN was lost and rails are earthed likely no real danger, may get some sparks when changing the points, but the question is should the PEN be lost and it is a TN-C-S supply who is at fault, the person who plugs into the supply, or the person who fitted the socket?

The installer is responsible for fitting it correctly testing and documenting. After that the owner is responsible for maintaining it.

Sockets installed on camp sites require double pole MCB & RCD so I'd guess yours should be installed the same if used for that purpose.

The funny thing was I had to make up a glass fibre enclosure containing such protection for the lorry yard at a company. I opted for 3 CU's fitted with main stitch, RCD, 1x 32A MCB for 32A socket & 2x 16A MCB for 16A sockets, total of 7 slots, and fed by a D63A MCB. it was delivered to site and installed by my colleagues. While the job was being signed off, physically at someones desk shuffling bits of paper and cheque he ordered another tith 12x 16A sockets for the camp site along the river, I priced for a bigger enclosure (to take , DP MCB's and individual RCD'd (total 0f 14 slots). The guy needed some persuading the additional cost of the second unit was required, this was a while ago but I'll imagine it was more than double.

AdrianUK · 7 Jun 2021

So, playing devils advocate here for the purposes of discussion....

A socket outlet (& I'm including Ceeforms here) is a general purpose thing intended for use by an ordinary person. Soooo .... that socket should be installed in a manner such that it is safe for use by the unskilled in the environment in which it is fitted.

This being in contrast to, say, a 'tailing-in point' which is intended to be used by a skilled person who understands what he is doing & how to deal with the risks....

SUNRAY · 7 Jun 2021

AdrianUK said:
So, playing devils advocate here for the purposes of discussion....

A socket outlet (& I'm including Ceeforms here) is a general purpose thing intended for use by an ordinary person. Soooo ....

Bearing in mind Ceeforms are provided 'as standard' for hook up points on campsites I'd have to agree the point, however they are not permitted in domestic situations so I'd have to disagree your point.

that socket should be installed in a manner such that it is safe for use by the unskilled in the environment in which it is fitted.

Every socket shoud be installed in a safe manner and for the environment.

This being in contrast to, say, a 'tailing-in point' which is intended to be used by a skilled person who understands what he is doing & how to deal with the risks....

I'd love to know where this is heading, at this point the two are polar opposites in my mind. In the mean time I agree a 'tailing in point' is way outside the permissable job for an 'ordinary person'.

Aragorn84 · 7 Jun 2021

SUNRAY said:
however they are not permitted in domestic situations so I'd have to disagree your point

AFAIK they are, they just need to be interlocked?

SUNRAY · 7 Jun 2021

Aragorn84 said:
AFAIK they are, they just need to be interlocked?

Don't you mean shuttered?

SimonH2 · 7 Jun 2021

Interlocked - as in you can't have live contacts accessible. If the plug is out, then power is locked off; if power is on, the plug is locked in.
Essentially the same function as shuttering - just a different route to achieving it.

SUNRAY · 7 Jun 2021

SimonH2 said:
Interlocked - as in you can't have live contacts accessible. If the plug is out, then power is locked off; if power is on, the plug is locked in.
Essentially the same function as shuttering - just a different route to achieving it.

But the interlocked sockets I've seen only stop the plug being inserted or removed when switched off, nothing to stop it being switched on with no plug inserted. After a hundred operations all of the flimsy nylon strips have failed anyway. Very unlike a 13A socket.

SUNRAY · 7 Jun 2021

But the interlocked sockets I've seen only stop the plug being inserted or removed when switched off, nothing to stop it being switched on with no plug inserted. After a hundred operations all of the flimsy nylon strips have failed anyway. Very unlike a 13A socket. My "known" experiences are resticted to MK & Gewiss although I used others.

JohnW2 · 8 Jun 2021

SUNRAY said:
But the interlocked sockets I've seen only stop the plug being inserted or removed when switched off, nothing to stop it being switched on with no plug inserted. After a hundred operations all of the flimsy nylon strips have failed anyway. Very unlike a 13A socket.

Interlocked sockets are equipped with an integral switch ensuring safe electrical disconnection and isolation. In order to prevent disconnection of the plug and socket coupling under load, it is not possible to turn the integral isolator switch to the ‘on’ position until a mating plug has been fully inserted. The plug cannot then be withdrawn until the isolator has been selected to the ‘off’ position

Kind Regards, John

SUNRAY · 8 Jun 2021

JohnW2 said:
View attachment 235838

Kind Regards, John

Ok I get that description but in my experience it doesn't apply to the MK or Gewiss unless they have all been faulty.

The very early interlocked sockets where the plug was inserted and turned clockwise about 45° were fine but they went out of fashion a long time ago.

I don't think I have any interlocked sockets at the moment as they are too big for portable work.

JohnW2 · 8 Jun 2021

SUNRAY said:
Ok I get that description but in my experience it doesn't apply to the MK or Gewiss unless they have all been faulty.

Fair enough. I have no experience of any, so cannot comment - I just remembered that the Lewden ones (which are what I posted) had the functionality described above - which (assuming it works!) sound very reasonable.

Kind Regards, John

SUNRAY · 8 Jun 2021

JohnW2 said:
Fair enough. I have no experience of any, so cannot comment - I just remembered that the Lewden ones (which are what I posted) had the functionality described above - which (assuming it works!) sound very reasonable.

Kind Regards, John

As it happens I installed some Lewden interlocked sockets between '96 to '02 to a previous design but I truly don't recall thier action.

bernardgreen · 8 Jun 2021

I recall from years ago 13 Amp plugs that had a notch on the Earth pin that enabled them to be locked into the interlocking socket when the socket was switched ON

SUNRAY · 8 Jun 2021

bernardgreen said:
I recall from years ago 13 Amp plugs that had a notch on the Earth pin that enabled them to be locked into the interlocking socket when the socket was switched ON

That sounds familiar too.

Also some metal clad 13A plugs and sockets with a lock ring which operated a switch as it was screwed on, if you were really careful it could be just far enough to provide just one pole and it was a toss up (between different devices) whether it was L or N. I never did work out how the switch operated so I didn't find a way of using a standard plug in them. They were particularly found in green houses.

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Sockets used for out door equipment who is responsible for safety?

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