I have no idea why you wrote all that.
Which part of what I wrote is incorrect?
Which part of what I wrote is incorrect?
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You wrote that the "OPD is too highly rated for the appliance flexes."
My "point" was that, while the UK requires 13 A (or lower rated) "fused" plugs in sockets rated at 13 A on circuits "protected" by 32 A (or 20 A) circuit breakers, other counties allow un-fused plug/socket-outlets which connect to circuits protected by circuit breakers with much higher rating than the plugs and "flexes" so connected.
My "point" was that, while the UK requires 13 A (or lower rated) "fused" plugs in sockets rated at 13 A on circuits "protected" by 32 A (or 20 A) circuit breakers, other counties allow un-fused plug/socket-outlets which connect to circuits protected by circuit breakers with much higher rating than the plugs and "flexes" so connected.
Ok.
Which countries are those?
Which countries are those?
Switzerland: overcurrent protection may be two sizes larger than the rating of the socket, commonly applied in the form of 10-amp sockets on 16-amp radials.
Belgium: 16-amp sockets on 20-amp radials
France: 16-amp sockets on 25-amp radials
Germany on the other hand tends to worry about 16-amp sockets on 16-amp radials if there are any extended overloads that remain within 1.45*In of the B16 MCB. At least some sparks do, others believe if the socket says 16 amps you're legally required to put it onto a B16.
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Thank you.
Or are there different intermediate ratings available?
Is it that loads greater than 10A in Switzerland and 16A in France and Belgium are not plugged in?
It seems some of the rules are just as ill-thought-out as the UKs.
What is the definition of a 16A radial if it is allowed to have a 20A (two sizes larger than 10A) overcurrent protective device?
Or are there different intermediate ratings available?
What is the reason for this?
Is it that loads greater than 10A in Switzerland and 16A in France and Belgium are not plugged in?
I would say that is obvious that you are but there are constant arguments about what a UK double 13A socket (or even a single) can handle.
It seems some of the rules are just as ill-thought-out as the UKs.
I was just giving examples, not necessarily complete lists of the arrangements used in various countries. I know that the French also use 25-amp sockets for large loads such as cookers and if I remember correctly, these are usually wired to MCBs matching the socket's nominal current. I don't think there are any loads fitted with a Type E plug that draw more than 16 amps but a power strip could easily be overloaded. The same is true for the US, where nothing prevents you from plugging a 15-amp power strip into a 20-amp NEMA socket, overloading the 15-amp plug and in some instances the flex. I believe the current regs require power strips to have 14 AWG flex, which is around 2 mm2 and shouldn't overheat immediately under a 20-amp load but you can certainly find plenty of older three-way extension leads with 18 AWG (0.75 mm2) flex still in use.
Switzerland has B/C13 MCBs, so two sizes larger than 10 amps is a B16. A T15 (16 amp) Swiss socket could be protected by a B/C25 if the information I've been given is correct.
I'd think every single country in this world has at least some questionable rules in the wiring regs.
Switzerland has B/C13 MCBs, so two sizes larger than 10 amps is a B16. A T15 (16 amp) Swiss socket could be protected by a B/C25 if the information I've been given is correct.
I'd think every single country in this world has at least some questionable rules in the wiring regs.
Ragnar_AT has provided examples of situations in some European countries.
At Post #30, I did show that, in Australia and New Zealand, the generally used 10 A plug can be inserted in socket-outlets rated from 10 A to 32 A - and the 15 A plug can be inserted in socket-outlets from 15 A to 32 A but not into a 10 A socket-outlet, and so on.
(The 10 A socket-outlets installed are usually in pairs [Photos 3 and 4 in https://www.plugsocketmuseum.nl/Australian1.html ] but "gangs" with 4 outlets are also available. https://www.bunnings.com.au/hpm-excel-4-outlet-powerpoint_p7050007 )
However, I neglected to mention that "normal" Australian/NZ 10 A socket-outlets are supplied by 2.5 mm2 cables, protected by 20 A Circuit Breakers (or RCBOs).
(When "Fuse" protection was/is used on 2,5 mm2 cable, the fuse rating is only 16 A)
I am still not sure what this is all about, but:
"normal" UK 13A socket-outlets are supplied by two 2.5 mm2 cables (or one 4mm²), protected by 32A Circuit Breakers (or RCBOs).
(When "Fuse" protection was/is used on two 2,5 mm2 cable, the fuse rating is only 13A)
However, my original point still stands.
Namely: for most items in the home (kettle, toaster etc) the 13A fuse in the UK plug is not really necessary.
also:
"normal" UK 13A socket-outlets are supplied by two 2.5 mm2 cables (or one 4mm²), protected by 32A Circuit Breakers (or RCBOs).
(When "Fuse" protection was/is used on two 2,5 mm2 cable, the fuse rating is only 13A)
However, my original point still stands.
Namely: for most items in the home (kettle, toaster etc) the 13A fuse in the UK plug is not really necessary.
You would know more than I do concerning such UK regulations.
However, considering that, in the UK, one can have a 20 A Circuit Breaker protected "Radial" with 2.5 mm2 cable off a CU feeding many 13 A Socket-Outlets, the use of a 13 A fuse on a "Spur" from a "Ring" does seem over cautious.
As I mentioned earlier, 2.5 mm2 cable was protected by 16 A fuses in Australia. I suspect that the same may have applied in the UK, since Australia developed much of its electrical practices from the UK (except, of course, the concept of a "Ring" - which is not allowed on "Low Voltage" circuits in Australia.)
I would agree with you, and include TVs, Radios, USB chargers etc.
Yes, but the problem is that there has to be A fuse in the plugs so people think it must be needed.
Also, when installing a spur with more than one socket on a 32A/2.5mm² ring, the example diagram in the regulations only shows the option of using a 13A FCU and 13A is the largest fuse anyway.
It does not show the use of cable with adequate CCC so people do not do it.
Yes - a legacy of BS3036 rewireable fuses and their 0.725 derating of the cable CCC.
The regulations for the special British ring circuit still applies for 30A BS3036 fuses even though MCBs would allow 40A to be used.
Did you just mean you are not allowed the anachronistic special British ring?
Would extending a compliant radial back to the CU to reduce volt drop etc. be allowed?
1. Yes
2. No
(Since a 2.5mm2 radial cable pair has a resistance of about 14 mΩ/m, even with a 30 m "radial" [with a resistance of about 0.42 Ω] at the maximum current of 20 A, the Voltage drop would be only 8.4 V
With a 240/230 V system, this drop is only about 3.5% and not really significant.
In North America with a 120 V supply, the 7% drop would be more significant.)
Instead of extending the end of a "radial" back to the CU, it would be just as easy to to run a new "radial" to any point of high current draw, with the need to provide an additional Circuit Breaker/RCBO.
When "window mounted" Air Conditioners were "in vogue" - about 40 to 50 years ago - it was often necessary to provide an individual 15 A outlet on a dedicated 2.5mm2 radial for them.
Virtually all Air Conditioners in this country are now "installed" (similar to Ovens) with a "dedicated" circuit of appropriate capacity.
The power drop ( loss ) in the cable is 20 Amp x 8.4 Volts = 168 Watt over 30 metres or 5.6 Watts per metre of cable
Since the total "draw" would be 4800 W, 168 W is still only 3.5% and 5.6 watts loss (heating) per metre of cable is (presumably) that which is deemed to be "safe", when enclosed in walls.
The size of cables supplying "loads" is determined by that which is considered to be both "safe" (for enclosure) and "economical".
Should anyone be concerned with reducing the losses necessary with physical distribution in any "installation", there is nothing preventing them from increasing the gauge of the wiring
concerned above the minimum required for the necessary safety, as specified by the regulator.
Economical matters
Some years ago the task was getting power to an equipment building some considerable distance ( several hundred yards ) from the nearest 230 Volt street cable
It was calculated that using a step up transformer at the supply end and running the long cable at a couple of thousand volts with a step down transformer at the equipment building was significantly cheaper than using a large cross section cable at 230 Volt.
Rules and regulations would not permit this economical solution.
A few years later when the equipment load increased an 11kV pole route was installed by the DNO
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