A Peek Inside A Typical British Residential Power Panel

No matter what field you’re in, it’s interesting and instructive to find out how others practice it. That’s especially true with electrical distribution systems, where standards and practices differ from country to country and even between regions. This tour of a typical British residential electrical panel is a great example of the different ways that the same engineering problems can be solved, and the compromises that always attend any design.

We’re used to seeing [Big Clive] tearing interesting devices to bits, but rest assured that this electrical panel remains largely intact as it gives up its secrets. Compared to the distribution panels and circuit breakers common in North American residential construction, the British consumer unit is a marvel of neatness and simplicity. True, the unit on display hasn’t been put into service yet, and things will no doubt change once an electrician is through with it, but the fact that everything is DIN rail mounted is pretty cool. [Clive] explains a few of the quirks of the panel, such as the fact that what looks like a main breaker is in fact just an isolation switch, and that there are a pair of residual current devices (RCDs), which we call ground-fault circuit interrupters (GFCIs) in North America, that also don’t act as circuit breakers, despite appearances. A stout bus bar is provided to link the RCDs to adjacent circuit breakers, forming two groups that are separately protected from ground faults.

[Clive] notes with dismay that the lugs of the bus bar can actually be inserted behind the rising clamp terminal on the breaker, resulting in poor connections and overheating. Still, we wouldn’t mind some of these concepts brought to panels in North America, which we covered a bit in a discussion on circuit protection a while back.

39 thoughts on “A Peek Inside A Typical British Residential Power Panel

  1. Professional installations in Brazil serve from best of two worlds (Nema and DIN), so things down here look as beautiful and functional as in the video. Of course not every installer or customer is always willing to pay for quality, so some panels do look (and function) like a mess.

    1. look neat and practical are two different thing.
      You can do a tidy routing ready for /r/CablePorn and curse installer for ten generation when you have to move a circuit or adding one.
      Or you can have less tidy one and spending minutes only to relocate circuit.
      And yes circuit relocation is a thing when you have GFCI on each row and excessive earth current (easy to reach with 30mA GFCI).

  2. Being in the UK, I like:
    – The DIN rail, it was easy for me to swap MCBs for RCBOs on the non-RCD side (my consumer unit was 16th ed, so now it’s more like 17th).
    I don’t like:
    – Not enough MCBs, for instance all sockets are on one ring, which means that switching off the MCB switches off every single mains sockets in the house. Likewise, all lights are on 1 MCB, so if you need to work on one light, you’ve got no more lights in the whole dang house while you work (need to plug something on a nearby socket… assuming you don’t need to switch off the ring MCB too!). In France for example, you typically get 2 MCBs per room (1 for lights, 1 for sockets), so you can isolate parts of the installation without disabling everything (e.g. during local work). Of course, this results in a massive consumer unit, but I don’t see it as a problem.

    I asked an electrician if he could split the ring, but he said that without knowing how/where it was cabled, it would be like re-wiring the lot.

    1. Modern installs in the UK would split the sockets into 2 or more rings – our house has downstairs, upstairs, kitchen as 3 separate rings.

      Likewise the lights, plus bathroom.

      When retro-fitting to an old house you can’t always split it as they didn’t expect to do that in the old days.

  3. In my opinion there are only two things which are allowed to not sit on a DIN rail: a beefy 24V DC power supply or a beefy frequency converter.

    just for static reasons…. :)

    I also prefer the screwless clamps. Have never seen one burned down, screwed ones many.

    1. What do you class as a “beefy” PSU? I recently replaced a ~1kW 24V DC supply on a top-hat rail. Luckily it was a SMPS not linear, so I could actually lift it! The panel designer had included extra support screws for the rail around the area of the PSU.

      1. 32 A (@ 230 V) fuse for the breaker on normal wall sockets? No wonder the UK has mandatory fuses inside every plug!

        I always thought that Brits were just super risk-averse. No, it’s that their each and every plug in the house can potentially carry 7.4 kW under fault conditions…

        So instead of a centralized, all-breakers-in-the-basement system, they have a few big breakers in the basement and tiny little fuses distributed around everywhere else.

        Thanks for posting that link. UK folks, I take it all back. You’re not mental, just different. :)

        1. we need decent power at the plug, waiting for a kettle to boil in a foreign country is an exercise in frustration. run a UK kettle and coffee maker at the same time in a non ring main wired country and your off to the breaker board. civilization starts with a good cuppa.

    1. Wait till you’re standing in front of a panel that has the master bedroom, master bath and the (semi-labeled panel is in the (dark) garage that you’re standing in.
      Damned panel had room for double the number of circuits, but the cheapout contract home builders seem to have mandated a lack of individual circuits and the use of receptacles and wall switches that must have cost about 11 cents each.
      Roughly 60 ft of wire and one more breaker would have done the panel right.
      I always use Spec grade or whatever it’s called now, when I replace receptacles and switches.

    2. Wow 10 circuits! Well most UK houses only need 5.

      It’s usually 30A (Old houses) or 32A (New houses) for a ring of 13A sockets. (Was 15A sockets in the 50’s)
      A ring of sockets is for the whole floor. Usually one 30/32A for upstairs, one 30/32A for downstairs and one for the cooker and kitchen.
      5A for upstairs lights and 5A for downstairs.
      That’s 5 fuses for the whole house. More fuses can be added for a bigger house, garage etc.
      Note we use ring circuits and not spurs. So 10 sockets on a ring = 1 fuse and not 10 fuses if all sockets are using spurs.

      1. I’ve just installed a new Consumer Unit that has 11 circuits in a rewired house. 2 Cooker points (hob and double oven) which is becoming the norm, 3 ring final circuits (Upstairs, groundfloor and kitchen), Boiler and central heating control, Immersion heater, Upstairs lights, Groundfloor lights, smoke alarms, Secutity alarms. Split boards are now becoming obsolete as they do not confirm to the 18th edition of circuit seperation. An earth leakage fault will take out the whole bank of circuits. All the boards I now fit are Main Switch and RCBO’s. Additions which are recommended for the 18th are AFDD’s and Surge protection so for a 5 circuit board you could be looking at a 12 way board to fit it all it

  4. How end sleeves are used here ist totally wrong, though

    Diameter reducing end sleeves because your (totally shitty) neutral terminal block won’t fit? This kind of terminal block was standard like, what 30 years ago?

    A COMBINIG end sleeve on a supply line?! For That alone you’d be stoned to death here in germany.

    I like to curse the damn VDE rules, which change every time, but when I see something like this described as a “marvel of neatness”, I understand that it’s a simple necressity.

    Ok, after I read up on “ring circuit”, I thought: “Ok, whatever, they really don’t care anyways…”

  5. Hmmm, as a US resident and electrical engineer who performs wiring on his own home and has installed a few main breakers, I’m not a huge fan of this design.

    The bus bars on the bottom are carrying a lot of current. Say what you will about the US panel, but the outside legs of the 240VAC transformer fed into the box at the top are then hidden in the middle of the breaker set. For a fully loaded box, it’s almost impossible to see of interact with.

    Having to break off the bars to suit looks like something that can be messed up easily. Based on the video, it looks like DIY installation is allowed, so that would worry me.

    US boxes look even cleaner than this when they are fully populated with breakers but have not had the wiring to the individual circuits installed. Thus, I think the comparison is flawed. You can make US wiring look extremely elegant, and many electricians and DIYers do. Nowadays, 200A service is pretty standard for new homes and remodels, and the boxes are enormous, allowing lots of room to neatly place circuit wires.

    I probably shouldn’t comment on this, as the box in the video might not be indicative of most local service, but having a red disconnect at the right that is not a breaker would bother me. I’ll admit I’m not completely up on code, but I’m not even sure you can have a sub-panel in the US without a master breaker for the panel. If you can, so be it, but most US residents assume there is a large breaker in a panel or subpanel that one can flip in a crisis to cut all power to the box. I think that’s a nice feature.

    The ordering of circuits based on rating is nice, and I agree it’s useful at times. But, I will admit ordering breakers by room or geographic location makes more sense to the average homeowner. If one can order by geography and then by rating, that’s fine.

    I think it’s odd that the new box doesn’t have a hole large enough for the connector. Maybe it’s that US boxes have a ton of punchouts, but I’ve never had that happen.

    I guess we’re biased with what we know, but I’m glad I don’t have to adhere to UK code. That ring circuit link is wild. Talk about a ground loop. It’s not to say the US code is perfect. The rules for placement around water is tough to discern at times, and they’ve recently removed provision to feed 3-way lighting to the light first and then to the switches, as I recall, which makes it harder to pull new circuits.

    1. DIY installs are not permitted. Google Part-P for more information on what the householder can/can’t do. Haven’t watched the video, but be assured, the big red switch at the end will turn everything off once the install is complete.
      And the bus-bars are properly rated, don’t worry. Remember we are exclusively 230V, so current is half that of most domestic US circuits.

      1. However the motivation behind part P ( of building regulations) was so totally misguided that it is widely ignored. An experienced engineer isn’t allowed to work on their own hose, but someone who has done a one week course and pays membership to NIC/IEC can.
        All parts are readily available in any DIY store.

        1. I wish a one week course and a membership fee were enough for me.
          My municipality has no exception for homeowners to DIY electrical work–only licensed electricians may pull permits and must perform all of the work.

      2. The UK does allow DIY install (it’s called work by a “non-competent person”) but unless it’s something that’s exempt from control it has to be inspected and certified by the local authority’s Building Control inspectors.

        The charges they make can be extortionate and for simple work often far exceed what an electrician would charge for doing the work. Where I live the standard charge is £245 for even the most minor work subject to control. A higher charge is only applied to a complete rewiring job when it goes up to £357 – which can easily save money on having the work done by an electrician.

        1. Or you just dont tell them. lol
          You take the limited risks of a section 36 enforcement and when you come to sell your house you buy an indemnity certificate for a mere 50quid or so.
          The loss of paperwork on true part P compliant jobs means indemnities are rife. It’s just tidying up the paperwork also as no one is ever going to claim on one.

          If you’re buying a house and dont take a full electrical inspection you’re taking a risk anyway. Your choice.
          Regardless of what a pipe of paper says, electricians are not all equal. Some are lazy and some dangerous.

          The competent persons schemes are about jobs for the boys. Else it wouldn’t be self certify !!

    2. ” I’ll admit I’m not completely up on code, but I’m not even sure you can have a sub-panel in the US without a master breaker for the panel.” You need a breaker for the panel, but it is placed in the other panel (the one feeding the sub). A master breaker panel is only needed for connecting to the service entrance. The main difference between the master and the sub is you can’t bond the neutral and safety ground in the sub panel, only in the master. That means you can’t run a 3-wire 240 circuit from a sub (one without a separate safety ground), you have to use a 4 wire circuit and terminal.

  6. In South Africa, the cheapest switchgear is DIN rail. The switches are wider than the alternates, but you get a good large contact clam, simplifying assembly. One thing we do differently is a convension of current flowing top to bottom and left to right. So the isolator is on the left followed by the earth leakage and then the overcurrent switchgear.

    1. I noticed the incoming earth on the video is thinner than the live and neutral. In South Africa live neutral and earth have to be rated the same so a 25 A circuit needs 25A L N and E, at the same time a 15 A circuit needed L N and E rated at 15 A.

  7. That’s a nice example of a brand new UK fusebox, but it doesn’t share much in common with the one in my house. (The house is from the 1870’s, and was probably electrified in the 1930’s going by the tarred canvas wrapped supply cable).

  8. An American residential breaker panel is as elegant and straightforward as it gets. It doesn’t have the flexibility of a DIN rail, but you don’t need flexibility when you’re installing breakers.
    You can install and remove breakers without turning off the main power. You attach the hot wire to the breaker, and then snap it into place. If you are careful, you don’t risk electrocution. I have done it many times.

  9. Amazing! Something that’s part of British power distribution that doesn’t look clunky like their power plugs. This actually looks pretty, but then it isn’t in use yet. (That title, “A look inside a British home electrical panel” is bosh.) When the UK bureaucracy gets finished approving it, it’s likely to look like yet another holdover from the 1930s.

    Check around and you’re likely to find that the electrical wars between countries is almost as heated as the one that we used to have between Windows and Macs. For the most part, I like our system, including the small plugs and the 115v supply (versus 230). My chief gripe against our distribution boxes in the US is that many components, such as circuit breakers, are vendor specific. That limits selection and raises prices.

  10. > what looks like a main breaker is in fact just an isolation switch, and that there are a pair of residual current devices (RCDs), which we call ground-fault circuit interrupters (GFCIs) in North America, that also don’t act as circuit breakers, despite appearances.

    That’s…incorrect.
    They all are circuit breakers. They will break the circuit when triggered. It’s just that they are triggered differently. The red-handled isolation switch needs to be triggered by a human to break the circuit. The RCD/GFCIs will be triggered by a ground fault and then break the circuit. And the things you seem to call circuit breakers will break the circuit in an overcurrent condition.

  11. It would be interesting to see comparison with Australia’s M-E-N (I shit you not… Mains-Earth-Neutral) powerbox setup. We’re nominally 230V I think, but I’ve seen between 230-260 out of a socket. Mix of star/daisychain on GPOs it seems. Older installs used one or two RCDs per install, but newer installs use combo RCD/breakers per circuit with RCD protection on lighting circuits also.

    In some ways it’s weird our choice of power plug – which I believe variants of are used in China and some other countries is from the US, but not what the US ended up going with. Polarised, doesn’t slip out the same way US plugs do as pins are angled.

    Standard GPOs are rated around 240V 10A so it’s not uncommon to see a kettle with 1.8-2kW rating.

    (I’m not an electrician, but I’ve done a bit of reading, and had a long chat with sparkie when I had him add some new GPOs + network points to our place)

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