3kW generator to internal socket

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Hi,
I recently bought this generator as in backup, in case of power cuts.


I will only be using to keep our fridge and freezers going, and to power the odd appliance, charge portable lights and electronics if the power was off for an extended time.

For that reason I don't want to have to have it professionally wired to the CU with a changeover switch, but I would also like something a bit more robust that just running a power reel as required.

I am going to locate it away from the house, and build an enclosure for it, but though that I could simply run some 2.5mm armoured cable to the house, to an internal set of sockets next to the fridge/freezers (any else that needs power can be moved there are needed).

I understand that it should not be connected to the existing house circuits, including the earth. But I have a few questions, that I would appreciate help with:

1) Is the above setup an OK idea?
2) What would be best practice to attach the armoured cable to the generator? (it is 3000W and 240V so I think a 13 amp plug would be OK, but is that undersized)?
3) Can I connect the other end of the cable to a 3-gang internal socket?
4) Could I spur another 2-gang socket from the first socket? (would ideally like to have 5 internal sockets, 1 fridge, 3 freezers and 1 spare for ad-hoc use)
5) What would be best practice with earthing?
6) Should I add some kind of RCD into the system? A passive RCD socket?

Any though would be very much appreciated.
 
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general comments not electrical connection wise
it may work a fridge a freezer a central heating boiler but not a kettle electrical heating or cooker off any sort and may fail on a microwave with any other load as a say 900w microwave is perhaps 1750w input as the only output mentioned is the microwave not the oven or grill they contain
it may or may not support a washing machine or tumble drier in low mode individually, i dont know but most modern machines seem to be sub 2000w so need checking but if flighting a cool beer cold sandwiches and underpants rotated 6 times are your hope then you may be fine :giggle:
 
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Thanks big-all.

Hopefully I won't need it at all, and if I do I will have to manage the load carefully.

I reckon it will easily handle the fridge and freezers, plus the occasional 600W microwaving (1000W rated) and a slow boil kettle. The only other significant load it might be used for is a 1000W/2000W room heater, but only if absolutely necessary.

In that situation, I would expect that the heater would be the only load on it at the time.
 
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It seems OK, but until tried not sure, two of my freezers would be OK as inverter drives on them, but the chest freezer is a single phase motor which has a high start amps.

I have considered one my self, but as yet not had a power cut here, if we do for an extended time, then it would be an insurance claim.

I have an open fire and loads of wood, so can keep warm.
 
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Thanks. I am going to give it some initial testing over the next few days, to see what it can handle.
 
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do you have close neighbours ??please keep them in mind a "whisper quiet noise" can be a major annoyance as a "hum or buzz" in the background
also consumption figures tend to be base on around 10-20 % average cappacity
 
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do you have close neighbours ??please keep them in mind a "whisper quiet noise" can be a major annoyance as a "hum or buzz" in the background
also consumption figures tend to be base on around 10-20 % average cappacity
Hi big-all.

I'm going to try to place it around 50ft from the house, am I also want to build a housing around it (for security, weather protection and also noise).

Not sure how quiet I will get it, but then again it is only for use in an emergency, so hopefully the neighbours won't be too bothered.
 
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you are then into volt loss due to cable length and resistance but on a light load probably fine but others will know better than me
 
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you are then into volt loss due to cable length and resistance but on a light load probably fine but others will know better than me
ignoring derating factors (which we DO have to take into account as this will be a fixed installation) 2.5mm² is usually good for ~25m @ 3KW

As to noise levels, offer the immediate neighbours an extention lead on a 3A fuse to run ther fridge/freezer.
 
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I also want to build a housing around it (for security, weather protection and also noise).
That could be tricky to get right. The main thing is making sure the exhaust goes outside so you don't create a box that gets very hot very quickly accompanied by lots of soot and carbon monoxide from running on it's own exhaust. And the exhaust is a major source of noise.

Electrically, you need to provide an earth that is independent of the supplier's earth - which can be lost if (e.g.) the cable in the street gets cut. Then, and without knowing anything about this specific genny, it may be wired in any one of several ways which mean that the fuse in the plug is not sufficient to protect against all faults. So you should have a 2 pole RCD between the genny and any loads which should deal with all reasonably forseeable dangerous situations (but may nuisance trip with some variations of genny wiring).
I would also suggest a double pole MCB at the genny end of the cable. This should be sized to protect the cable - someone might come along later and connect a larger genny, at which point the cabling might not be adequate - you are probably thinking this won't happen, but it's hard to predict what someone else might do.

Since you plan to permanently site the genny, it should be fairly easy to install an earth electrode for it. Connect it to any earth terminal on the genny frame, and also to the CPC (earth wire) in the cabling to the house.
This does then introduce some interesting questions around bonding.
You will now be bringing a local earth into the house which is different to the earth provided by the DNO. So your freezer could be connected to the local earth, while the sink within touching distance is connected to the DNO earth - which may be at a different voltage, in extreme, a dangerously different voltage. This is the reason for bonding all conductive incoming services (i.e. metal gas and water pipes) as they enter the building, which means that even if the DNO earth isn't the same as local earth, everything inside the house is at the same voltage.
So to deal with this, the local earth and DNO earth should be bonded together - and this requires (from memory) a minimum 10mm² cable.

You can run any number of sockets from this genny supply, branched however the wiring runs suit.

For the physical connection, you are now looking at a 4 way metal enclosure to house the 2 pole MCB and 2 pole RCD (or 2 way box to house a 2 pole RCBO if you can find one). The SWA will gland into this, and then you can take a short flex out though a stuffing gland with plug on the end to suit the genny. At the house end you'll want a small junction box to gland the SWA into and take one or more cables out to the sockets - a metalclad socket & backbox can do double service as both a socket and junction box for this.
Technically, it may be possible to use the SWA armour as a CPC, but to avoid having to work this out, just use 3 core SWA - and earth the armour to the CPC at both ends.
But note the above about possibly needing a 10mm² bonding cable. This could be a separate single core cable, in which case you could use 2 core SWA and the bonding cable doubles up as the CPC for the circuit. The bonding cable should follow the same route as the SWA, and not be liable to damage that might mean you lose your bonding and/or earthing.


Sorry, that's longer than I planned to write :rolleyes: If you search, you'll find plenty of threads about connecting generators, and the common theme is that "it can get complicated" due to the number of variables and the fact that some of them are generally outside the scope of the person installing the facility. It becomes somewhat simpler if the genny is hardwired so that the whole system can be correctly designed, and any changes mean using tools (hence done hopefully by someone with a clue) rather than just plugging something in.
The biggest issue is earthing since doing it one way means that plugging a different genny in could mean things aren't earthed properly; while doing it a different way would cause some generators to burn out (due to part of the winding being shorted out). And if it's a plug in facility, then there's no control over what gets plugged in.

Simon

Interesting that the pictures show the genny being used on what looks like it is some sort of construction site. I doubt you'll find any in this country that allow the use of 240V portable tools :eek:
 
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Thanks very much @SimonH2.

Lots to work through there, and all very much appreciated.

I've started by having a look at some DP RCBOs, and I am wondering if this one is OK, in this enclosure?


I'm not entirely clear on the various RCBO types, so any guidance would be much appreciated. I have read somewhere that residential requires Type A, so not sure the Wylex one will be OK.

It is 16A, but the next one down is 10A, so I think that 16A will protect the cable, but also allow the full 3kW.

I also stumbled across this, while searching, which has RCD and a 16A MCB. Could I use it, rather than buy the separate bits?

 
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If you charge their phones and their kids iPads they will consider you the best thing since sliced bread, I'm sure
What usewould they be without internet?
Even the mobile phone base stations will be off until (that is IF) the provider gets to providing generators.
 
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I'm not entirely clear on the various RCBO types, so any guidance would be much appreciated. I have read somewhere that residential requires Type A, so not sure the Wylex one will be OK.
I also got caught out, in may case fuse box RCBO, clearly marked type B, and my thought was "Oh did not expect that, type A would have been good enough." however the type B referred to being curve B, not type B, in my case it was type AC in the one you show it is type A and curve B which is ample.
The biggest issue is earthing since doing it one way means that plugging a different genny in could mean things aren't earthed properly; while doing it a different way would cause some generators to burn out (due to part of the winding being shorted out). And if it's a plug in facility, then there's no control over what gets plugged in.
This has been the problem I have found, mainly with duel voltage generators, where the earth is bonded to a centre tap of one winding, not neutral, so if you bond neutral to earth it causes a short circuit. Most generators have an earth bolt, to connect the earth to, any earth rod should be connected to that bolt, and then the earth for items used is taken from the socket on the generator.
What use would they be without internet?
Even the mobile phone base stations will be off until (that is IF) the provider gets to providing generators.
This has been a problem for many living around here, they have been installing fibre for telephone and internet, and the unit in the house has a battery back up, so it will still work with a power cut, but the box down the road does not have battery back up, so no power no land line, so can't phone up to say my power has gone off.

Many years ago Prestatyn got flooded, and all the mobile phones failed, at that time RAYNET was still active (Amateur Radio emergency network) and they were able to set up coms for the emergency services, today there are far fewer radio hams, internet has replaced what they did with radios, and many RAYNET cells have folded, so not sure what would happen today? I have looked at local phone boxes, one is a book swap, the other has medial kit in it, neither have phones any more.

When high winds took out the local mobile mast earlier this year, I lost my central heating as it detected my phone was not at home and auto went into Eco mode, now disabled.
 

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