in this Q and A video we're going to answer the question am i allowed to install
round pin sockets and plugs according to the regs
in a recent video Gary and Gordon reviewed a clever dimmer switch from the MK Base range and
as part of their demonstration rig they used a couple of unusual socket outlets and plugs
with round connections instead of the more common rectangular pins which led a
few people to ask if this plug and socket arrangement was acceptable for use still
well the accessories in question comply with the British standard that in fairness is pretty old
namely BS546 now this standard bears the year 1950 on it which does make it fairly antiquated however
a quick glance at the BSI shop website shows its status as current so it's still a valid standard
but is this a bit of an oversight maybe it should have been retired but
it had been missed well let's look at BS7671 and see what it says with regard to this standard
under heading 553.1 plugs and socket outlets we find regulation 553.1.3 where we read
except where regulation 533.1.5 applies in a low voltage circuit every plug and socket outlet shall
conform with the applicable British standard listed in table 5 5.1 in table 5 5.1 we find a
list of plug and socket types that are acceptable for use in our installations and we've got our
familiar BS 1363 socket which is described as fuse plugs and shuttered socket outlets two pole earth
for AC however in the next line down we find a slightly different arrangement where we read
plugs fused or non-fused and socket outlets two pole in earth and if we track across to the
British standard column we find the BS 546 so you can see there that we can indeed use BS 546 plug
and socket connections however there are a couple of provisos to this the regulation immediately
after table 5 5.1 states that every socket outlet for household and similar use shall be of the
shuttered type and for an AC installation shall preferably be of a type complying with BS 1363
so there's two key points here if the socket is in a domestic setting then it must be shuttered
BS 546 sockets come in both shuttered and unshuttered formats so you'd use a shuttered
one in someone's home and it also says that the preference in this type of installation is a BS
1363 but notice that's just for preference not an absolute also for a ring final circuit we find
this direction in regulation 433.1.204 accessories to BS 1363 may be supplied to a ring final circuit
with or without unfused spurs protected by a 30 amp or 32 amp
so that very specifically directs that we need to use the square pin sockets for a ring final
circuit and there's no mention of being able to use sockets complying with BS 546 so where in a
domestic setting might you decide to use a BS 546 socket well one example would be for a lighting
application if we turn to regulation 559.5.1 under the heading connection to the fixed wiring we read
at each fixed lighting point one of the following should be used for the termination of the wiring
system then indent 5 a suitable socket outlet complying with BS 1363-2 BS 546 or BSEN 60309-2
so let's say you want to operate a standard lamp in the corner of a living room from a switch by
the door you'd wire from the switch to the position of the socket outlet for the lamp
now we mentioned the regulation earlier that said in a residential setting the BS 1363 sockets are
preferred however might there be a disadvantage to this in this particular application well if
you're operating that lamp from a lighting circuit then it'll probably be protected by a 6 amp MCB
so if someone came along and plugged in a hoover or a heater then they're going to trip the circuit
so using a round pin socket complying with the BS 546 could be an acceptable solution as long as
it's shuttered also in a domestic setting you'll probably want to use a plug with sleeve pins
to prevent contact with live parts when inserting and removing the plug of course there may be
issues with fusing the supply down and such like if the lamp requires protecting with a smaller
fuse and it is possible to get fused BS 546 plugs for circumstances like this as with any circuit
the key to using BS 546 sockets successfully is making sure that the equipment installed
is correlated to the protective device supplying it after all we don't have fuses in plugs
complying with BSEN 60309 or commando sockets as they're also known so there we go as long as we
bare in mind some key points we can indeed use BS 546 round pin sockets in our installations
and still comply with BS 7671 but as always we want to hear from you do you install this type of
socket outlet on a regular basis or have you never used them would you be comfortable installing them
in a domestic setting after what we've discussed in this video please leave your thoughts and
questions in the comments section below and as always thank you very much for watching