16 amp circuit.

[Jake]

Was I? I didn't think so.

Oh, OK, apologies - what did you mean then?

 

[RogerS]

.....
As the wisdom/foolishness of having a 16A rated unfused socket protected only by a 32A breaker, well a fool might think it wise and a wise person might think it foolish.

And a pragmatist would look at the 8ft length of cable between the socket and the machine and ask the question...is this really going to develop a short circuit of such specific 'short-circuidness' that it will blow a 16A breaker but not a 32A breaker??

 

[dicktimber]

You can't see it..electric I mean.....
so don't dabble, dibble, consider, or think this should work......

Get a chap in that knows!!!!

and if you don't....
make sure your insurance company will pay out to work done by uncertfied DIY electricians
mike

 

[RogerS]

You can't see it..electric I mean.....
.....

No..you can't but you can measure it and Ohm's law is still valid :wink:

 

[Jake]

And a pragmatist would look at the 8ft length of cable between the socket and the machine and ask the question...is this really going to develop a short circuit of such specific 'short-circuidness' that it will blow a 16A breaker but not a 32A breaker??

How do you know how long the length of cable is?

And why are you assuming a simple short circuit fault, rather than something more complex.

Oh, I forgot. It's because you know more than the IET (urgh) because the BCO said so. :lol:

 

[RogerS]

And a pragmatist would look at the 8ft length of cable between the socket and the machine and ask the question...is this really going to develop a short circuit of such specific 'short-circuidness' that it will blow a 16A breaker but not a 32A breaker??

How do you know how long the length of cable is?

And why are you assuming a simple short circuit fault, rather than something more complex.

Oh, I forgot. It's because you know more than the IET (urgh) because the BCO said so. :lol:

Ever the lawyer :wink:

Of course I don't know how long the cable is...any more than both of us know if his cable is man enough to be supplied by a 40A breaker. But one can take a more reasoned and pragmatic view (although I do appreciate that pragmatism has no mileage in court).

I'm giving the OP the benefit of the doubt that (a) he is intelligent and (b) might just realise that that hot burning smell might indicate something was amiss...even though the MCB hadn't dropped out and/or (c) that he didn't leave his equipment running overnight all by itself.

I'm not suggesting that the 'land of make believe' pragmatic solution is the optimum (optimal?) choice but if he doesn't want to go the whole hog and get in an electrician to wire in a new 3-way CU then my approach is an alternative.

And Ohms' law still holds.

 

[Jake]

I'm giving the OP the benefit of the doubt that (a) he is intelligent and (b) might just realise that that hot burning smell might indicate something was amiss

I have no doubt about the former, and trust that he'll apply it to the right advice. The latter takes a leap through some assumptions.

...even though the MCB hadn't dropped out and/or (c) that he didn't leave his equipment running overnight all by itself.

How do you think the two legs of this ring are adequately protected - and where on the ring is this socket positioned?

I'm not suggesting that the 'land of make believe' pragmatic solution is the optimum (optimal?) choice but if he doesn't want to go the whole hog and get in an electrician to wire in a new 3-way CU then my approach is an alternative.

And Ohms' law still holds.

Optimal is nicer, there.

Why the false dichotomy? You seem to be saying that he needs to get an electrician in to do a proper job, but to do a bodged-up non-compliant job he doesn't?

Personally, I think the better advice is to do the optimal job, either way. Even, I would say, especially so if you are going to not get an electrician in.

I am interested in how Ohms law helps your cause?

(Oh, and have the IET not realised it exists?)

 

[OLD]

When you do a electrical job its a good idea to use best practice you have a 40a feed .New box with rcb (better protection) + 2x 16a mcb (16a +ring )&5a mcb (lights) thats 5ways used look at garage distribution units in toolstation and screwfix and you are adding 1x 16a mcb.

 

[RogerS]

.....
How do you think the two legs of this ring are adequately protected - and where on the ring is this socket positioned?

That's irrelevant if you think about it. You're concerned about potential overloading. Think about it. On the existing ring main there is absolutely no reason why two 2kW heaters could not be plugged into the same double socket. That's a total of 16amps (continuous and not a brief 16A on startup as would be the case with a machine). So any inherent faults in the ring main are just as applicable to its' existing purpose. Posit a spur of this same socket and another 2kW heater plugged in - that's 24amps now... do you concede the point?

So what we're really concerned about is protection for the cable from the ring main to the machine and the machine itself.

Consider the cable...Just what kind of fault do you envisage can happen to the cable that will blow a 16amp breaker but not a 32amp breaker? I can't.

Consider the machine. It's not going to be left on all night so we don't need to worry about it overheating in the wee hours. So we need to consider a fault on the machine that's going to take 17amps (for the sake of argument) - ie sufficient to blow a 16amp breaker but not the 32amp breaker. That's a total of just over 4kw being dissipated in that machine (assuming a phase factor of zero ...which is technically incorrect for a motor but does give worst case figures). Do you really think that that the OP is going to sit there getting hotter and hotter?

It really all depends on the upheaval and cost that the OP is willing to take (over there in far away land). Connecting the 16amp lead into the existing ring by removing a socket and terminating the cable there is eminently retrofittable and he can go back to the status quo.

Technically, of course, he shouldn't be doing anything of the sort because a workshop comes under Part P (and we all know now what a waste of time that is given my and Old's threads on our own experiences).

 

[Jake]

On the existing ring main there is absolutely no reason why two 2kW heaters could not be plugged into the same double socket.

The ring main is as I say, subtle - one of the assumptions it is based on is that people don't do that. The socket design is based on the same assumption, which is why a double socket has the same 13A rating as a single socket.

That's a total of 16amps (continuous and not a brief 16A on startup as would be the case with a machine). So any inherent faults in the ring main are just as applicable to its' existing purpose. Posit a spur of this same socket and another 2kW heater plugged in - that's 24amps now... do you concede the point?

You can very easily overload a ring if you try - it is a delicate pragmatic balance based on reasonable assumptions and expectations as to how it will be used, with a cap on each outlet via the fuse protection.

So what we're really concerned about is protection for the cable from the ring main to the machine and the machine itself.

Consider the cable...Just what kind of fault do you envisage can happen to the cable that will blow a 16amp breaker but not a 32amp breaker? I can't.

Do you accept cable ratings at all then?

Consider the machine. It's not going to be left on all night so we don't need to worry about it overheating in the wee hours. So we need to consider a fault on the machine that's going to take 17amps (for the sake of argument) - ie sufficient to blow a 16amp breaker but not the 32amp breaker.

But you've put this on a ring - how do you know what other loads are on it? Your three 2kW heaters for instance.

That's a total of just over 4kw being dissipated in that machine (assuming a phase factor of zero ...which is technically incorrect for a motor but does give worst case figures). Do you really think that that the OP is going to sit there getting hotter and hotter?

I dunno - it seems to me in your example he's pretty cold - why else does he have the three heaters on?

It really all depends on the upheaval and cost that the OP is willing to take (over there in far away land). Connecting the 16amp lead into the existing ring by removing a socket and terminating the cable there is eminently retrofittable and he can go back to the status quo.

It is very little more effort to do the job properly.

Technically, of course, he shouldn't be doing anything of the sort because a workshop comes under Part P (and we all know now what a waste of time that is given my and Old's threads on our own experiences).

I'm no fan of Part P, especially if it encourages rather than discourages a cavalier attitude. I'm all in favour of (responsible, educated) self-wiring - I don't think that entails putting homespun 'common-sense' over the carefully thought out regs, designed by expert electrical engineers to ensure that wiring is as safe as it reasonably can be.

Admit it, it is a pointless lazy bodge - it will save about £15 tops, and about ten minutes work.

 

[Digit]

Sorry about the late reply Jake I've been swearing at a new computer, why don't they understand what I want them to do? :lol:
I was simply observing that this sort of action is carried out by people and observing an old saying.
On a different tack there seems to be an assumption on the forum that a ring main means 32 amp fusing. That is not so.
My machines run on dedicated radial lines with a ring for the hand tools, vacuum cleaner etc and fused at 16 Amps.
The ring main was introduced after WW2 as a means of reducing expensive copper imports, the radial main was still the preferred option with fused 15 amp plug tops, ( haven't seen one of those for years now)

Roy.

 

[Jake]

Sorry about the late reply Jake I've been swearing at a new computer, why don't they understand what I want them to do? :lol:

No problem. They don't seem understand what I want them to do either - especially when I ask them to fetch me a beer.

I was simply observing that this sort of action is carried out by people and observing an old saying.

I see. I hope you can understand and forgive my mistake in thinking that you were endorsing its application to Roger's comments, rather than just typing it out apropos of nothing much other than it was a common saying.

Any reason you chose that one, rather than, say, "the early bird gets the worm"? :lol:

On a different tack there seems to be an assumption on the forum that a ring main means 32 amp fusing. That is not so.
My machines run on dedicated radial lines with a ring for the hand tools, vacuum cleaner etc and fused at 16 Amps.

True - it's just the standard (and max), and therefore a reasonable default assumption.

 

[Digit]

No problem Jake, as I've commented before, the short comings of the written word.

Roy.

 

[ike]

Admit it, it is a pointless lazy bodge - it will save about £15 tops, and about ten minutes work.

Actually, I think you've nailed it there.

 

[ivan]

True, but older heads like mine will have grown up with unfused 15A plugs, with the sockets fed by a ring main, and protected with a 30A bit of fuse wire. At the introduction, there were a lot of 'stupid safety nonsense' grumbles about the 13A fused plug system.

Whilst not tickety boo, putting one 16A socket into a ring main protected by a 30A breaker is an improvment on the fuse wire system of my youth.

 

[big soft moose]

Admit it, it is a pointless lazy bodge - it will save about £15 tops, and about ten minutes work.

isnt this biting the hand that feeds ?

without the "pointless lazy bodge" the legal fraternity would have a lot less work litigating for negilgence claims

 

[Jake]

True, but older heads like mine will have grown up with unfused 15A plugs, with the sockets fed by a ring main

Radial, surely?