Over Current Protective Device for Socket Outlets

Europe has similar rules.

Wire size there is in mm2. Outlets in most countries have to be wired with 2.5 mm2 and the number is limited per circuit. Years ago, when I left it was 7. - or 7 double outlets. Some circuits like the bath rooms and kitchens must be separated and protected individually with some very sensitive earth fault detection. The circuit protector must protect all the components and the wires.

UK installations are to BS7671

UK plugs to BS1363 are internally fused up to 13A. Sockets are frequently connected to a ring circuit. A 2.5mm cable is run from the consumer unit via each socket in turn and finally returning to the CU the where the two ends are connected in to a single 32A MCB.

I believe depending on floor area and whether the sockets are wired in ring or radial circuit the sizes of MCB and wire varies.

BS7671/2008 will become BS7671/2012 shortly (1^st of January). The standards are amongst the highest in the world. From what I've seen of American and Canadian systems I wouldn't hold them up for comparison.

Your socket outlets are no match for safety. US MCB's in particular have a worldwide reputation for unreliability. Cabling is abysmal.

Sorry No Contest!

BS sockets have different ratings like 5A,13A and 15A, in addition there is 20A DP switch with indicator. Normally 13A ,15A & 20A radial circuits are protected by 16A & 20A MCB.13A sockets in ring circuits have 20A or 32A MCB as well as 2.5 or 4 mm^2 wire depending on the area(sq ft or sq m) of the room. How many 5A sockets could be wired radially and the cable size to be used in a 6A,10A and 16A MCBs?.

I would have a look at BS7671/2012 before commenting.

BS1363 plugs can be fused internally at 1, 2, 3, 5, 7, 10 and 13A. All quite happily connected in to a standard socket fed from a ring on a 32A MCB or a radial with a 20A MCB. We have no need of various sockets for differing loadings.

5A sockets are occasionally used for table lamp outlets controlled from the lighting circuits with a 6A MCB. These 5A sockets are to the same safety standard as their 13A counterpart. They are only installed to stop "the wife" plugging the vacuum cleaner in to the lighting dimmer.

I have found a table of circuit arrangements for 13A BS 1363 sockets,according to which

if installed in accordance with Appendix 5

a)ring circuit with 30/32A PD-pvc cable(2.5) or MICC cable(1.5),max floor area 100 sq m

b)radial circuit with 30/32A cartridge fuse or mcb,pvc cable-4sqm or micc-2.5,area-50

c)radial circuit with 20A PD,pvc-2.5, or micc-1.5,area-20 sq m

Note that quantity of sockets in a circuit is not given.

Why don't somone give NEC or VDE codes regarding sockets(receptacles)?.

<...quantity of sockets in a circuit is not given...>

That's because the quantity of sockets in a circuit is not restricted, as the circuit is protected by its circuit protective device(s) at the distribution board.

The only thing that is restricted is the number of spurs in a ring circuit not exceeding the number of sockets in that ring.

Hi One & All,

My understanding that the basic principle is that the fuse has to protect the wire size so it will not over heat.

BEN

It has to protect the weakest item. In principle the 2.5 mm2 can work with a 30/35 Amp fuse, although the regular outlets are not fit for these, probably except UK. Correct me if I'm wrong but Belgium, the Netherlands and Germany secure this with 16 Amps. Unless special outlets of a higher rating are used.

As I am sure the Holy and Most High BS standards aforementioned in these posts do refer to the same electrical characteristics that all Electrical engineers contend with. In order to stay on-topic, regardless of the standards or short-circuit protection devices used, it is important to take into consideration the following guidelines.

The Branch breaker (MCB) must protect the lowest rated device in each circuit and is sized at 125% of the device rating or at 100% if the breaker is HACR rated.

The Branch feeder cable must be able to carry the current that can be supplied by the breaker.

The Mains Circuit Breaker (MCB) Protects the panel board and is calculated differently so does not apply to your question.

To be specific, your 16A rated receptacle can be protected by a 20A breaker or a 16A HACR rated breaker. A 2.5mm cable can be used in either case except if the cable run is excessive due to voltage drop.

How can it protect the lowest rated device in any circuit when you consider a small load like a table lamp(60W) connected to a socket and protected by a 6A MCB?.

To the OP; when you are asking about the rules, is this just for general knowledge? or are you considering undertaking a wiring project?

If it is the latter, we really cannot tell you for sure. You really need to be asking your local AHJ (Authority Having Jurisdiction)

While we can quote how it s supposed to be done in our own locations, the rules could be (and most likely are) different in Indonesia. Only you local AHJ can tell you for sure.

If it is just for general knowledge then carry on It is always neat to here how it is done in other places.

The purpose of the current protective device is to protect the conductors irrespective of AHJ. If you use a larger MCB then the conductors may be exposed to currents beyond their intended purpose/rating. For more info please verify the conductor size and the circuit length.

Sometime people in the UK forget that BS 7671 only applies to electrical installations and that there are also other standards that are relevant depending on what you are trying to do, plugs & sockets maybe installed into other situations, eg if you are building a machine (note the exclusion in BS7671). You might need to consider EN 60204 series for example.

I'm sure that the same could apply elsewhere (other equipment covered by European regulations, lifts, medical equipment, radio equipment etc maybe?)

Also remember there are industrial plugs and socket up to 64A (I think).

In the UK & Europe you also or might have to consider instead BS EN 60309 Plugs, socklet-outlets and couplers for industrial purposes.

Another thing BS 7671 is not a listed standard for CE marking.

So BS 7671 mustn't be seen as the "holy of holy's" cause it ain't!

Thank you very much everybody.

I am still confused on how large circuit breaker can protect 16A Receptacles.

If 32A a MCB (miniature circuit breaker) protect 7 pieces of 16A Receptacles with 6 mm2 cable, cable will be protected by the MCB. However, you can connect a load of 32A to one of the 16A Receptacles without tripping the MCB. Is this allowed in your country?

By NEC, this is simple. 15A Receptacles can be protected by 20A Circuit breaker, but not by 30A or greater one.

Regards

<...allowed...>

It's not possible in this country.