I live where pore cuts are frequent. I have a 5.5kw generator and want a manual system for changeover. What would be the gear to provide between the board primary output and my consumer unit to provide a safe and effective way to couple the generator in?
Generator feedin
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Hi you will need a generator transfer switch kit
Like this
http://www.ebay.co.uk/itm/CHANGEOVE...ls_Supplies_Electrical_ET&hash=item417c2ea57b
make sure you use a transfer switch such as this otherwise you'll back-feed the power network killing workers such as myself.
minimum 6mm but best to fit 8mm cable for less voltage drop, from the transfer switch to a wall mounted 32 amp socket, then you can connect straight up to your generator using a standard 32a lead
hope this helps regards Chris
Like this
http://www.ebay.co.uk/itm/CHANGEOVE...ls_Supplies_Electrical_ET&hash=item417c2ea57b
make sure you use a transfer switch such as this otherwise you'll back-feed the power network killing workers such as myself.
minimum 6mm but best to fit 8mm cable for less voltage drop, from the transfer switch to a wall mounted 32 amp socket, then you can connect straight up to your generator using a standard 32a lead
hope this helps regards Chris
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Thanks, I agree that expecting the generator to supply the potential full load is unwise. I had thought of putting the generator in the garage and feeding the supply backthrough the garage cable but that's only 2.5mm wire although the earth is 5mm plus the armour wire. I will investigate the switch box further.
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Well probably would be your best choice is to have a second consumer unit supplying circuits you using during power cuts.
You can feed the second consumer unit from a breaker in the main consumer unit and have a smaller transfer switch between the two units.
like this one http://www.tlc-direct.co.uk/Products/KMT338212I.html
You will still need to run at least 6mm cable from the generator to the transfer switch (advise 8mm if your running the generator for a long time)
You can feed the second consumer unit from a breaker in the main consumer unit and have a smaller transfer switch between the two units.
like this one http://www.tlc-direct.co.uk/Products/KMT338212I.html
You will still need to run at least 6mm cable from the generator to the transfer switch (advise 8mm if your running the generator for a long time)
The electrics forum might be a better place for this, if you ask a mod nicely they should be able to move it for you. I think the way to do it is to click on the "Alert Moderators" link and ask, perhaps someone will correct me if that's wrong.
Bear in mind that this will be notifiable work (in England or Wales, not sure about Scotland & NI). It also needs properly designing and testing, which requires knowledge and test gear that few DIYers will have. For example, what earthing system do you have, and how do you propose to provide an earth when using the genny ?
Apart from that, installation is actually quite simple. L&N from the mains goes to one input on the switch; L&N from the genny goes to the other input; and the output of the switch goes to L&N in your CU.
Personally I wouldn't bother splitting circuits - why complicate things ? Just bung in a 32A intake, you'll soon learn to manage demand - be careful when cooking the sunday dinner if the cooker is electric, and don't try running lots of electric heating or the garage welder.
What you MUST NOT do is what it sounds like you were thinking of doing - and backfeed the house through the garage supply. If you do that, then you cannot have a changeover switch, and you cannot avoid the risk of having a) plugs with live pins and/or b) trying to backfeed the local grid which (as Furball points out) is highly dangerous (and in cases, fatal) to people working on the supplies.
The common way of doing it is with a lead with two plugs on - one fits the genny, the other fits a socket in the house. These are called (for good reason) "widow makers" because they allow for both the hazards I've just mentioned.
A changeover switch (if properly installed) prevents both problems as the generator and mains supply cannot be connected either to each other, or to the house at the same time.
Bear in mind that this will be notifiable work (in England or Wales, not sure about Scotland & NI). It also needs properly designing and testing, which requires knowledge and test gear that few DIYers will have. For example, what earthing system do you have, and how do you propose to provide an earth when using the genny ?
Apart from that, installation is actually quite simple. L&N from the mains goes to one input on the switch; L&N from the genny goes to the other input; and the output of the switch goes to L&N in your CU.
Personally I wouldn't bother splitting circuits - why complicate things ? Just bung in a 32A intake, you'll soon learn to manage demand - be careful when cooking the sunday dinner if the cooker is electric, and don't try running lots of electric heating or the garage welder.
What you MUST NOT do is what it sounds like you were thinking of doing - and backfeed the house through the garage supply. If you do that, then you cannot have a changeover switch, and you cannot avoid the risk of having a) plugs with live pins and/or b) trying to backfeed the local grid which (as Furball points out) is highly dangerous (and in cases, fatal) to people working on the supplies.
The common way of doing it is with a lead with two plugs on - one fits the genny, the other fits a socket in the house. These are called (for good reason) "widow makers" because they allow for both the hazards I've just mentioned.
A changeover switch (if properly installed) prevents both problems as the generator and mains supply cannot be connected either to each other, or to the house at the same time.
It's not disconnecting the neutral that's the issue - the earth is split off upstream of the switch so in theory the combined N&E would still provide the earth (assuming a TN-C or TN-C-S system). Even if it's a TN-S system, there's no guarantee that the DNO staff aren't working on the system and have disconnected the earth as part of that work.
But, if the mains supply is off, there's no guarantee that the supply cable hasn't been cut and the neutral lost somewhere between your cutout and the DNO's earth.
I'm not qualified to answer, but I suspect it's "complicated". AIUI you aren't allowed to put a switch in the PE, and you aren't supposed to locally earth your MET in a TN system.
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Single plug and two sockets I have used in the past. All items which I want to put on generator go in their own consumer unit then on the main consumer unit I put a socket of same type as used on generator. So when there is power it's plugged into mains and with power cut unplug from mains and plug into generator.
This simple method means when the generator goes for service you can hire replacement and simply plug into that one instead.
Also impossible for any fault to every cause both to be connected together.
Also it takes more time to change over so fridge etc motors have stopped before power comes back on so less likely to damage them.
It also means the earth is also disconnected from mains and connected to generator instead any earth rods connected to generator will not be also connected to mains earth unless you decide you want to cross bond. That would depend on mains earthing method to start with.
This simple method means when the generator goes for service you can hire replacement and simply plug into that one instead.
Also impossible for any fault to every cause both to be connected together.
Also it takes more time to change over so fridge etc motors have stopped before power comes back on so less likely to damage them.
It also means the earth is also disconnected from mains and connected to generator instead any earth rods connected to generator will not be also connected to mains earth unless you decide you want to cross bond. That would depend on mains earthing method to start with.
But you are required to bond it to any pipe or metal work that might import an earth imto the building.
Don't worry the electrons will know it is a bond and not an earth cable and act accordingly /sarcasm of the regulations
If the generator is not earthed ( absolutely NO direct or leakage path of any sort from generator to ground ) then shocks between generator Live and Earth ( ground ) would not be possible. However it would be difficult to ensure there was no path between generator chassis and ground so mild shocks could happen.
Same applies if you fit a changeover switch and inlet - you can use whatever genny you like as long as you have a lead with one end to fit the genny and the other to fit your inlet.
We often hear that, but I don't know where it is comes from. As Bernard has said, it would make absolutely no sense, given that one is not only 'supposed', but definitely required, to connect the MET of a TN system to any and every earthed conductor which enters the building!
Kind Regards, John
Well I do know that some years ago a mate had the DNO come round telling him they were altering the supply - I assume from TT to TN-C-S. They specifically looked for and disconnected the earth rod - but did leave the bonding on the copper water pipe accessed through the same hole in the floor.
So yes, they insisted on removing a local earth, but not the bonding which did much the same thing. As bernardgreen suggests, we've got intelligent electrons round this way
So yes, they insisted on removing a local earth, but not the bonding which did much the same thing. As bernardgreen suggests, we've got intelligent electrons round this way
As I think we are all agreed, removing the connection to the earth rod is totally unnecessary in that situation (although leaving it connected will achieve nothing in the absence of supply-side faults - so maybe the DNO man was 'just being helpful' by disconnecting something that was 'no longer required'). It would be particularly silly for anyone to suggest that a local earth rod was 'not allowed' with TN-C-S since it's in the nature of PME (which inevitably goes with TN-C-S, at least in UK) to be 'used to' multiple earths!
There is, of course (and for very good reason) a prohibition of having two different earthing systems in the same installation - but a DNO earth and local earth electrode which are 'bonded' together is a single earthing system, not two.
Kind Regards, John
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