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Kitchen Socket Solution

  1. Oct 5, 2009 #1
    Can anyone help with a little household problem I have?
    In the kitchen we have a microwave, coffee maker and toaster that unfortunately are only within reach of 1 double socket. This means constant swapping of plugs. I'd like a neat, safe and practical solution to this problem.
    Toaster: 1700w
    Coffee Machine: 1450w
    Microwave: 1400w

    The existing socket is not a spur despite this I am conscious that I'm sailing reasonably close to the wind in terms of load if I use the existing wiring. Is there anything out there that would give me a way connecting three appliances that will fit in the same pattress? The appliances are pretty static - so I wouldn't mind losing the plugs in favour of some sort of triple switched, triple fused unit. I'm 80% sure that nothing like this exists and the folks on here with much more electrical experience will tell me to just get a spark in to do me another socket off the ring.... but just in case :)

    UK Wiring by the way 230v, ring main 2.5mm2 conductor

    Thanks
     
  2. jcsd
  3. Oct 5, 2009 #2

    HallsofIvy

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    I don't claim to be an expert (and I would hate to be responsible for burning down someone's house!) but I would think a "surge protector" like I have my computer, printer, etc. hooked to would work. It has multiple outlets and a built-in circuit breaker.
     
  4. Oct 5, 2009 #3

    mgb_phys

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    UK ring main load is 13A so you could run two appliances at once.
    Easiest is simply to plug the two you are least likely to use simultaneously (toaster/uwave) into a double plug adaptor.

    Don't use a 4gang style adaptor sitting on a worktop that could be covered in water!

    The problem with getting in an electrician is that the wiring regs will probably have been tightened since your house was built and the current socket might be illegal under the new regs. Unfortunately they tightened all the rules a couple of years ago to force you to get an electrician in to do anything - which naturally led to a lot of very unsafe solution like running extension leads from one room to another.
    It's legal to change a socket, replacing a 2way with a 3way - it comes under minor modifications exemption - but not in a kitchen - that's a 'hazardous area'.
     
  5. Oct 5, 2009 #4

    jambaugh

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    First check to see if your fuse or breaker for that circuit is 20A. 2.5mm will handle up to 30A but let's keep things at 20A which is barely sufficient to run all three appliances.

    You also want to be sure the outlet itself can handle 20A. As you say you're running "pretty close to the wind" here but still within tolerances. I see online 13A is a pretty common domestic rating for 2-way splitter adapters. I'd suggest you use one for Microwave and coffee maker and plug the toaster directly into the other half of the double socket. The toaster + other will exceed 13A.

    That setup should handle all three appliances at once (just barely) but you can make a point of only using at most 2 at a time to be extra careful.

    But I'm most worried about your outlet rating. I'd suggest you upgrade to a 3-way rated 20A or higher. It would also be very wise to install a ground fault detector socket given the water potential in the kitchen. You need a ground wire to install a GFD but your 2 conductor won't have a ground. If your water pipes are metal from kitchen to the mains then you could clamp a ground line to the cold water pipe and fish it up to the outlet.

    Personally I'd do this sort of thing myself but you may want to consult with an electrician. Also, if you are renting then be sure to consult your lease agreement to see if there are any issues.
     
  6. Oct 5, 2009 #5
    Thanks Jambaugh, does all of that hold true for UK? we have massively different implementation here. For instance - every socket has earth here. All runs are two conductors + an uninsulated earth.
     
  7. Oct 5, 2009 #6

    mgb_phys

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    UK ring main main fuse is 32A - they are wired as a ring so you can pull twice the current as a spur.
    With 220V and the 13A fuse in the plug you can get about 3KW/appliance.
     
  8. Oct 6, 2009 #7

    jambaugh

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    Ah, OK then all the easier to install a ground fault interrupter aka ground fault detector.

    Here in the US some circuits only have 120V 1 hot plus 1 insulated "earth" for the circuit, others are 3 conductor 1 hot, 1 insulated return "earth" and an uninsulated "earth" for safety grounding. One needs the 2nd ground to install a GFI/GFD device.

    The wattage calculations I used are direct:
    Current x Voltage = Power - or - Current = Power/Voltage.

    I'm using 10 AWG which is 2.588mm as a comparison. The NEC (National Electric Code) recommendation for 10 gauge wire is 40Amps max free air, 30 Amps max as part of 3-conductor cable. I'd say 20 amps for 2.5mm is well within safety limits. (Your local code is another matter.)

    Again I would emphasize that the limiting factor is probably going to be the rating of the outlet (socket). Make sure it can handle 13A per plug and 20A total. And don't scrimp on the splitter. Make sure it is rated at 13A continuous load. Higher would be better.

    Ideally you should install a whole new > 20A rated heavy duty 3 outlet wall fixture with built in ground fault interruption circuit.
     
  9. Oct 6, 2009 #8
    Yeah how you guys ended up with the U.S wiring system is a complete mystery to me..... UK ring main isn't any better though - plenty of shortcomings.
    I might go through building control and sort a few bits and pieces around the house at the same time. At £350 a time to have work signed off by a part P spark - I'm seriously tempted to do the study and become qualified. Looks like I could do for it for less than £1000 including membership with one of the bodies.
     
  10. Oct 6, 2009 #9

    jambaugh

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    Thought about it myself except here (in Georgia, US) you must apprentice for four years just to qualify to take the exam.

    As far as our system of wiring goes... what can I say. It makes sense to me but I grew up with it. At the box we have 240V between two "hot" buses either of which may be connected to a power ground (earth) for 120V. Usually major appliances with heating elements or heavy motors are wired to 240V. Lighting and outlets (sockets) are 120V. Heavier load outlets typically have a 2nd ground.

    If I were emperor I'd redesign the whole mess, especially the power plugs.
    I'd like to make all outlets 240V + power ground with plugs designed to select which voltage they use.
    A "T" configuration [ | - ] for 120V and
    an "H" configuration [ | -- | ] for 240V with ground.
    A single outlet would be able to connect 1 H or two T plugs.

    One advantage would also be that plugging in two 120V appliances would balance the load between the two hot circuits.
     
  11. Oct 6, 2009 #10

    mgb_phys

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    USA's 120V makes more sense because it's harder to electrocute yourself.
    But you can only take half as much current on the same size wire, so a kettle in the US takes twice as long to boil - which means they can't make a decent cup of tea.

    Large appliances can't take enough current from a regular 120v socket. So instead of running an expensive high gauge cable (like you might do to run an electric shower or immersion heater in the UK) they take 2x 120V feeds and connect them as +/- 120v giving 240V to run appliances such as washers/driers. (Note this isn't the same as two phase - although people think it is.)

    The UK started to use ring mains (where all the sockets in a room are connected as a bus which goes back to the fuse box) after WWII to conserve copper. It takes much less wire (at least in a small UK house) than running a separate line back to the fuse box for each socket. It also lets you use twice as much current since each socket has effectively two identical live wires back to the fuse box.

    The UK used to be pretty relaxed about doing the work yourself - the electricity company would just give it a quick look over before they connected it to their supply.
    Then they introduced a rule where to do anything more than changing a light bulb needed an electrician. It was estimated that 5 (!)people a year died doing DIY electrics - these people of course will continue to do it themselves and win Darwin awards - but it means when you sel your house you have to prove that an electrician did all the work.
    But it's a real pain for anyone else - especially if you live in an old house and have to explain to some Youth training Scheme qualified 17year old that this isn't a ring main because it's 50years old and they should use the 16A fuse you have fitted not the 32A one they have a picture of in their book.

    <sorry rant over !>
     
    Last edited: Oct 6, 2009
  12. Oct 8, 2009 #11
    Swap it all for 400v 3 phase. I need a 20hp blender. In a couple of generations we'd have a super-race of people who aren't harmed by high voltage electricity!
     
  13. Oct 8, 2009 #12

    uart

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    Personally I'd just put the toaster and the microwave together on a good quality double adaptor (or powerboard if it can be placed somewhere convenient and safe).

    The reasons for choosing the toaster are that it's typically intermittent with short duty cycle but even more importantly that it's almost never operated unattended. (You don't usually put on some toast and then go out for the day while it's toasting).

    The main issue (as jambaugh already pointed out) is likely to be the socket itself. If it draws too much current it could get warm, if it gets really overloaded it could get hot enough to start to smell (and finally in the worst case scenario if very badly overloaded, to start a fire). All this takes time and so is much less likely with an intermittent load. It is also much less likely with an attended load as the burning smell is a dead give away.

    BTW. If you try both loads together like that it's a good idea to run it for a while and then feel to see if the socket is indeed getting warm. A tiny bit warm (like barely lukewarm) is not necessarily a problem.
     
  14. Oct 8, 2009 #13

    mgb_phys

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    UK sockets are rated at 240V/13A (3.2KW) so no problem running two appliances together.
     
  15. Oct 12, 2009 #14
    Would a spur be acceptable? I don't see that this is worse than a power strip or double adaptor. I was thinking of putting a switched spur outlet next to the current double socket. I would hardwire the microwave to this and label it as such.
     
  16. Oct 12, 2009 #15

    uart

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    Yes I don't think you'd have anything to worry about there, especially since they're all relatively intermittent loads. Just make sure the breaker is good for at least 20A.
     
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