Continental plugs don't have fuses, so why does UK?

[ban-all-sheds]

Now imagine that we had 15/16A radial circuits with fused plugs,

There would be no point to fused plugs.

and shutters and all the other features of BS1363, and someone said let's remove the fuses from the plugs, remove the shutters and switch to unpolarised plugs.

Shutters and polarisation are unconnected with ring/radial designs.

CEE 7/7 plugs are polarised, and there are shuttered sockets.

It is my opinion that fused plugs and shuttered/polarized sockets are safer than unfused plugs and unshuttered/unpolarized sockets because they eliminate potentially dangerous situations.

On the contrary, when you rely on fuses for protection because the circuit OPD is too large, and those fuses can be replaced with the wrong value (or bypassed completely) by people who don't know what they are doing, you create an opportunity for dangerous situations.

The reason I believe that ring mains are better than radials is that they require less copper.

That's been shown to be wrong.

 

[JohnW2]

The reason I believe that ring mains are better than radials is that they require less copper.

As I said before, that's not necessary the case. It depends a lot on the required maximum load 'per circuit'. If 20A (or maybe even 25A, given appropriate conditions and finding a 25A MCB) per circuit is considered adequate, then ....

... take any 2.5mm² ring circuit. Remove the cable joining the middle two sockets. Separate the two legs of the ring at the CU and feed each from its own 20A (or maybe 25A) MCB. You now have two radials, providing appreciably more capacity (40A or 5A) than did the ring (32A), and the radials are using a little less copper than did the ring.

Kind Regards, John

 

[EFLImpudence]

Remove the cable joining the middle two sockets. Separate the two legs of the ring at the CU and feed each from its own 20A (or maybe 25A) MCB. You now have two radials, providing appreciably more capacity (40A or 5A) than did the ring (32A), and the radials are using a little less copper than did the ring.

While your having that done it would be advisable to uprate the cooker circuit to 10mm² 'just in case' you buy an industrial kiln and

oh! better fit 25mm² tails 'just in case' they replace your 60A fuse some time in the future.

 

[JohnW2]

Remove the cable joining the middle two sockets. Separate the two legs of the ring at the CU and feed each from its own 20A (or maybe 25A) MCB. You now have two radials, providing appreciably more capacity (40A or 5A) than did the ring (32A), and the radials are using a little less copper than did the ring.

While your having that done it would be advisable to uprate the cooker circuit to 10mm² 'just in case' you buy an industrial kiln and
oh! better fit 25mm² tails 'just in case' they replace your 60A fuse some time in the future.

Eh? You've totally lost me there. I was merely illustrating that, contrary to what had been asserted, radials do not necessarily use more copper than rings - I wasn't saying anything about 'future proofing'. I must be dim - what was your point?

Kind Regards, John

 

[EFLImpudence]

No, I wasn't contradicting you but sarcastically stating what goes on.

There isn't much point working out whether rings or radials use most copper when numerous cases exist on various forums where wasteful over-engineering of circuits is taking place because 'electricians' just do things because they do.

 

[JohnW2]

No, I wasn't contradicting you but sarcastically stating what goes on. There isn't much point working out whether rings or radials use most copper when numerous cases exist on various forums where wasteful over-engineering of circuits is taking place because 'electricians' just do things because they do.

Oh, I see - I was being a bit dim/slow

What you say is obviously very true. However, I think there are some situations in which the subsequent hassle of upgrading cables (e.g. if they are underground, or extensively buried in building structure) may justify 'wasting' some copper in the name of a degree of 'future proofing'!

Kind Regards, John

 

[JBR]

...and someone said let's remove the fuses from the plugs...

...they wouldn't work at all!

 

[jabuzzard]

Now imagine that we had 15/16A radial circuits with fused plugs,

There would be no point to fused plugs.

As I stated earlier a 3A flex on a 15/16A radial circuit is still unsafe and still needs fusing for maximum safety. The alternative is to use properly rated cable for all flexes. However this is bulky and leads to use of large amounts of copper so is not done.

Consequently while the difference might be low in deaths, injuries and damage to property there will be circumstances where a fuse in the plug would have prevented a problem.

Consequently it is safer to have a fuse in the plug than not to have a fuse in the plug if the use of flexes rated below the maximum capacity of the outlet are in use.

 

[JohnW2]

Consequently it is safer to have a fuse in the plug than not to have a fuse in the plug if the use of flexes rated below the maximum capacity of the outlet are in use.

Whilst that is literally true, I think it might take you a lifetime of hunting to find examples of an appliance flex ever having done any harm in the manner you are considering. In the scenario being considered, the chances of a fault arising that could result in the flex causing harm without also causing a 15A/16A PD to operate are probably incredibly small. There are far, far, greater risks in everyday life.

Kind Regards, John

 

[EFLImpudence]

There would still be 433.3.1(ii)

 

[JohnW2]

There would still be 433.3.1(ii)

Indeed. That's essentially what I was saying (in different words) when I said that a fault causing overload (but not 'fault') would seem to me to be extremely unlikely. However, jabuzzard appears to believe that, in some (unspecified) situations, overload current is 'likely'.

Have said that, and to be fair to jabuzzard, he was not really discussing the situation under regs 'as they are' but, rather, was talking about the consequences of disappearance of the requirement for (fused) BS1363 plugs. In such a hypothetical scenario, many of the associated regs would probably also change - so it's anyone's guess as to what they might say (including what they might say about the CSA of appliance flex).

Kind Regards, John

 

[securespark]

Cor blimey! This still goin'?