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Thread: 20 amp Dedicated circuit install

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    Jay
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    20 amp Dedicated circuit install

    As some of you may or may not know I have a fair amount of server / network equipment running at home. I am soon to be moving house and putting the rack into the new garage, the issue is that there are no decent power outlets in the garage.

    I was thinking of getting a dedicated 20amp circuit installed into the garage but I am not actually sure what the cost of this would be.

    Does anyone here know what kind of costs I will be looking at for this?

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    Re: 20 amp Dedicated circuit install

    The breaker itself isn't that expensive, but the cost depends on the ease or otherwise of running cable to the garage, and if there is a spare way in the consumer unit for the new breaker.

    If there is already power to the garage, as part of a ringmain in the house, I'd be tempted to leave it be. Otherwise you have to find where the garage feed goes off to the garage, remake the ringmain at that point, and then extend the cable bck to the consumer unit.

    If the garager supply is spurred off the ringmain, you still need to extend the spur back to the new breaker.

    If the house is new build, you might be able to get the work done as part of the building process.

    If it is additional work, something like this falls under part P of the building regulations, so it has to be approved/inspected by a comptetent person.

    Cost? |MNaterials are the smallest part, labour will be the largest part, and will depend on the amount iof work involved. Might be worth getting sa couple of quotes dfrom some electicians and your electricity supplier. but I'd be surprised if it was less than £200-£250 - but all depends on the time and work involved.
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    Re: 20 amp Dedicated circuit install

    Quote Originally Posted by peterb View Post
    ....

    If it is additional work, something like this falls under part P of the building regulations, so it has to be approved/inspected by a comptetent person.

    .....
    Good job I did mine before the reg's changed, innit.

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    Re: 20 amp Dedicated circuit install

    Are you sure you are going to need 20 amps?

    20 X 230 = 4600 watts

    4.6 * 10p (cheap electricity) = 46p an hour

    = £4029.60 a year.

    If you are drawing that level of current, your kit is in the wrong place.

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    Re: 20 amp Dedicated circuit install

    Peak current demand can be brief, though. The fact that you can draw 20A in a worst case peak doesn't mean you draw 20A all the time, any more than a 32A cooker circuit costs £6k a year.

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    Re: 20 amp Dedicated circuit install

    Quote Originally Posted by Saracen View Post
    Good job I did mine before the reg's changed, innit.
    Good job I have got a drum of 2.5mm twin and earth in the old colour scheme (which changed when the new regs came in!)
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    Re: 20 amp Dedicated circuit install

    Quote Originally Posted by peterb View Post
    Good job I have got a drum of 2.5mm twin and earth in the old colour scheme (which changed when the new regs came in!)


    That didn't cross my mind. Not for a moment. You sneaky ol' bleep, you. I wish I'd done that.





    PS. Notes, in passing, that sales of old colour cable shot into the stratosphere on the changeover, as the trade discovered an urgent 'need' for extra stock, and became about as easy to find as fresh rocking horse poop.

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    Re: 20 amp Dedicated circuit install

    Quote Originally Posted by peterb View Post
    Good job I have got a drum of 2.5mm twin and earth in the old colour scheme (which changed when the new regs came in!)
    As has my old man. Lots of it. Lots.
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    Re: 20 amp Dedicated circuit install

    Out of interest what's with the need for stockpiling old cable? DIY work that doesn't need to be checked?

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    Re: 20 amp Dedicated circuit install

    Jay, wouldn't you simply put in an additional 30amp ring if you are going to all the trouble of running new wires from the fusebox?

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    Re: 20 amp Dedicated circuit install

    These days electricians seem to favour radial circuits rather than rings. Alot of them use 20amp MCB's and 4mm^2 cable radials as they are easier to test.

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    Re: 20 amp Dedicated circuit install

    Quote Originally Posted by Whiternoise View Post
    Out of interest what's with the need for stockpiling old cable? DIY work that doesn't need to be checked?
    Technically it still needs to be checked if thework was done after part P came into force. However, the cable colours also changed on that date and so using the old cable on a pre-part P installation means that you can't tell when it was done.

    Of course the same argument might be applied to new cable on a new installation, who is to say when it was done or that it wasn't part of the original installation?

    Quote Originally Posted by Sputnik View Post
    These days electricians seem to favour radial circuits rather than rings. Alot of them use 20amp MCB's and 4mm^2 cable radials as they are easier to test.
    Ring mains tend to be a British 'thing' and were introduced after WW2 (I think) when copper was in short supply and there was a lot of house rebuilding going on. Prior to thaty, most houses were radially wired, with each circuit protected by a single fuse, and that is also the case in contental Europe.

    In the UK, high current ccts like cookers, electic showers and immersion heaters are radially wired.

    Lighting ccts are probably where ring topology is justifiable as the connected load is relatively low and constant, unlike a socket cct where the connected load is variable, and if the ring becomes broken, the cable rating could be exceeded in one of the broken legs, as the single current carrying capacity is lower than the two halves of the ring in parallel.

    Radially ccts are safer, and more versatile - and have the advantage that a fault on one cct does not switch off equipment on any other cct, but does use more cable.
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    Re: 20 amp Dedicated circuit install

    Quote Originally Posted by peterb View Post
    unlike a socket cct where the connected load is variable, and if the ring becomes broken, the cable rating could be exceeded in one of the broken legs, as the single current carrying capacity is lower than the two halves of the ring in parallel.
    Even if there is not a break, The load on each leg can vary depending on the location of the sockets (by cable length) drawing the load. If the socket is only a few metres away from the consumer unit on one leg it is unlikely to have a 50% load on each leg.

    The other consideration is we now have lots more electrical appliances in our homes and many heavy load items in the kitchen especially which makes having a couple of radial circuits in the kitchen a good way of sharing the load sensibly.

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    Re: 20 amp Dedicated circuit install

    Quote Originally Posted by peterb View Post
    Technically it still needs to be checked if the work was done after part P came into force.
    There are exceptions and some crazy ones at that.

    If your replacing like with like generally no. So if the mains supply to your garage was done by 'billy bodge it' using telephone cable (dangerous of course) and you replace it with the same - not notifiable but, If you want to change it with the correct cable type - notifiable.

    Crazy isn't it ?

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    Re: 20 amp Dedicated circuit install

    Quote Originally Posted by Sputnik View Post
    Even if there is not a break, The load on each leg can vary depending on the location of the sockets (by cable length) drawing the load. If the socket is only a few metres away from the consumer unit on one leg it is unlikely to have a 50% load on each leg.

    The other consideration is we now have lots more electrical appliances in our homes and many heavy load items in the kitchen especially which makes having a couple of radial circuits in the kitchen a good way of sharing the load sensibly.
    Very true. Interestingly, in France (and maybe other countries) it isn't unusual to have a three phase supply to the house, which adds a new dimension to load balancing across the three phases. (a friend of mine has a house in France with a three phase supply and had that problem, particularly as he has a heat pump for heating a swimming pool) And of course ensuring minimum separation between sockets on different phases.

    Quote Originally Posted by Sputnik View Post
    There are exceptions and some crazy ones at that.

    If your replacing like with like generally no. So if the mains supply to your garage was done by 'billy bodge it' using telephone cable (dangerous of course) and you replace it with the same - not notifiable but, If you want to change it with the correct cable type - notifiable.

    Crazy isn't it ?
    Yes, quite a few anomolies!
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