BIGGEST DIY Mistakes Adding a New Socket

this video will cover common mistakes DIYs make when adding a new socket to an existing circuit existing socket circuits will either be a radial or a ring circuit a radio has a single cable coming out the consumer unit going to each outlet in a line with the cable stopping at the final Outlet so the final socket we'll just have one cable going into it and no cable going out of it whereas in a ring the final socket has two cables still so there's one cable going in and the other one goes back to the consumer unit ring circuits came in during the second world war when the UK government mandated their use in order to save copper as they enable people to put a higher current through a 2.5 millimeter cable than it was actually rated for now 2.5 millimeter cable is typically rated at 20 amps as you need to make allowances and derate the cable depending on the run so just clipped in free air 2.5 millimeter cable is rated at 27 amps but if it's run through installation the safe rating Falls to 17 amps or even 13 amps ring circuits are typically on 32 amp Breakers so you would think that this would exceed the Safe Load on the cable but as the current has two legs or paths to travel along the chance of any individual leg exceeding 20 amps is low as the load is split across the two directions this is the theory anyway in reality the load does not split evenly this is why the rules for ring circuits state that the cable rating must be no less than two-thirds of the rating of the protective device being the breaker so say if you took two-thirds of 32 amps a 32 amp circuit that will give you about 21 amps which is approximately your cable rating for a 2.5 millimeter cable the problem with ring circuits comes when you get a break in the ring in my experience brakes are usually loose cables coming out the back of sockets where people haven't done the screws up tighten up in a scenario where only one cable has come out of the back of the socket but the other one is still in there making contact you won't notice any issues with any of your sockets they will all still work perfectly but you actually have a break in that ring now in the scenario where you've got a ring and you've got a break in the ring your socket tests are like this will still show up as no issues whereas if you've got a break in a radial circuit the error is immediately obvious this is because there's only one path back to the consumer unit you haven't got two paths so what you essentially get is two radial circuits on a 32 amp breaker So in theory if you had some energy thirsty appliances on one leg of that broken ring you could in theory pull 32 amps along a single cable that's only rated for 20 amps which could cause damage to the cables in your home without you knowing this is one of the reasons why electricians must do what's called a ring continuity test on any rings they work on in order to ensure they have a complete ring and there's no loose connections or no broken connections personally I think the ring circuit should be removed from the regulations as if a break were to occur in the ring it's possible for the cables to become overloaded without the homeowner knowing or any obvious issues showing fortunately rings have started to fall out of favor more recently with electricians tending to opt for radials rather than Rings now and going back to the original reason why Rings got introduced in the first place saving cables in my opinion I don't think they actually really save any cable at all because you could just split your ring into two radials and have them on two separate 20 amp Breakers and you'd have actually a more capacity in total with actually slightly less cable although you would need an extra space in your board for an extra breaker old-fashioned rewireable fuse boards tended to have many fewer circuits in them the modern boards do now old boards could have had as few as four fuses on them whereas now typical consumer unit has around 10 circuits or 10 Breakers but very large houses could have many more circuits than that now one of the most common methods of adding a new socket to a circuit is to take a Spur off an existing socket by just running a single piece of twin and Earth from your existing socket on the ring or on the radio to your new socket which is an absolutely okay thing to do the issue comes when people add multiple sockets to that spur this is because 2.5 millimeter cable is typically rated at a maximum current of 27 amps so if you have a double socket with 230 and amp appliances plugged in in theory the maximum current you'll be pulling through that single piece of cable is 26 amps and for something that's probably raised at a Max of 27 amps that's absolutely fine however if you were to put a second socket off that spur you could in theory plug up to 52 amps worth of appliances into those four sockets four times thirteen now rings are typically on 32 amp Breakers so you'd never be pulling 52 amps through that spur but in theory you could pull 32 amps through it which would exceed the max rating of that cable of 27 amps and ultimately could cause damage to the cables the reg state that you can't have more than one single or double socket on a spare off a ring like this you might think it would be okay to put 2 two single sockets off a Spur because in theory you wouldn't be exceeding your 26 amps but the regulations remove this allowance in the 1970s reason being there was a risk that people would down the line convert those single sockets into doubles and then you would have potentially two doubles on a single spur if you do need to add multiple sockets to a Spur you could use a fused connection unit or FCU or for use spur this essentially limits the current on the spur to 13 amps then you could add multiple sockets Daisy chained off that fuse spur however you'd only be able to plug in low power appliances into those sockets because you're always going to be capped at that 13 amps because that's what the fuse will be rated for in the fuse spur but unless you've got heaters to plug in most appliances these days are fairly low power so that would be absolutely fine the next error is using cable that is too thin to be used on socket circuits now lighting circuits typically use 1.5 millimeter cable or even one millimeter cable where a socket is typically 2.5 millimeter cable now the thicker a cable is the more current it can carry lighting circuits don't need much current carrying capacity as lights just don't use much power whereas socket circuits must use at least 2.5 millimeter cable so wiring to any additional sockets needs to also be using 2.5 millimeter Cable in order to be compliant and safe the next area is taking a Spur off your oven or shower radio you might need a socket somewhere where there isn't another socket easily accessible but there might be an oven or a shower nearby that does have a power supply for example if you needed a socket in a Cupboard say next to your oven but there's no easy way to get a Spur there from an existing socket you might think oh perfect I'll just take a Spur off the oven circuit for my new socket the issue with this is that showers and ovens tend to be very high power appliances and as a result so have fit cables and they're usually on Breakers that could be 40 or 50 amps so if you just spur a socket off that in theory that socket could pull 40 or 50 amps which would seriously exceed the rating for it although plugs should have a maximum fuse size in them of 13 amps so it's unlikely this would ever happen but there's always the danger the fuse wouldn't blow the next mistake is spurring a socket off a lighting circuit now you might find you want to add a socket in your Loft but find there are no socket cables up there but instead you might find cables up there that are for the lighting applying a permanent live to ceiling roses you might think perfect I'll just Spur off that for my socket in The Loft however this isn't okay lighting cables are designed for much lower current than sockets with thinner cables typically one millimeter or 1.5 millimeter and breakers on lighting circuits are typically three to six amps so whilst those Breakers would likely protect the cable from any damage people could have put an inappropriate fuse wire in a rewireable fuse or worse just use a piece of copper wire in a rewireable fuse or the MCB could fail so you could still pull much more current through those cables than they're rated for by putting a socket on a lighting circuit in this scenario where you need a socket in your Loft but have no cables up there for sockets I would suggest finding an existing socket somewhere else in the house that's on an exterior wall then drill a hole through the back of that socket to outside then run a Spur off that socket up the outside of the house and into the Loft however be sure to not use regular gray twin and Earth as this is not rated for exterior use over time the PVC sheathing will degrade in the UV also be sure to add a drip Loop so you don't have any water just running down into your wall the next mistake is people running cables outside of zones there are prescribed wiring zones in houses try and mitigate the risk of people accidentally drilling into a wall into a live Cable cable should only be run horizontally or vertically from sockets and light switches or in corners of rooms this way people know where to expect them to be and to not drill in those places if you run cables diagonally buried in plaster people won't know they're there and won't expect them to be there and as a result May drill into them accidentally next mistake is not using safe plates where I'm running cables through joists or studs safe plates prevent screws or Nails accidentally piercing a cable when someone's screwing or nailing into a stud or a joist these are inexpensive and easy to fit and in my opinion an essential item to use when running new cables or pipe work through joists or stud walls I hope you enjoyed this video thank you for watching please like And subscribe for more

Channel: The Diligent DIYer

Views: 387,241

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Id: dyVh4V7W_Eg

Length: 10min 16sec (616 seconds)

Published: Wed Feb 15 2023