Temp generator to supply domestic CU during power outage

[redpis]

Hi All,

I have a few questions and would like your opinion and advice on please, recently houses local to us have had a power outage for 30hrs, and this got me thinking (dangerous I know) about using a generator to feed essential circuits.

The house supply is TN-C-S
Crabtree Starbreaker split load CU

What I was thinking is to install a Gewiss GW66004 switched socket outlet fed from a 10A RCBO on the non RCD side of the CU, (The genny is only 2.2kVa)

The genny would be plugged in using a modified plug at the genny end (neutral & earth joined)

Also I would install an earth electrode using 16mm to the CU earth bar

Operation would be:

1 Isolation and locking off of the main incoming supply at the CU when utility power is lost
2 Isolate MCBs except lighting and sockets (loads disconnected except FCU feeding heating)
3 RCBO to genny socket on and backfeed into board

Whats your thoughts,

Cheers

 

[mfarrow]

The problem you've got is that you're still leaving open the possibility of the supplies being paralleled if you forget to switch the incomer off, or isolate the generator once power is restored. Also, the plug and socket arrangement has the potential for live pins to be exposed when unplugged. You also need the neutrals to be separate (i.e. two pole switching). Therefore, use a changeover panel or switch on the incoming tails.

The rest of it sounds OK, but you will want to treat the installation as a TT when running off the generator (you don't want to rely on the suppliers earth at this point), and therefore install an RCD+MCB/RCBO to the generator output.

EDIT: here's what you need: http://www.genpoweruk.co.uk/product.php?productid=16157

 

[ban-all-sheds]

My thoughts are that you were right - your thinking is incredibly dangerous. Widowmakers, risk of backfeeding the public supply...

Please get someone in to do this who won't end up breaking the law or killing themselves or other people.

 

[skenk]

NO!

If you need a socket when the power goes off and you have a generator then buy yourself an extension lead - hey presto!

As far as i'm aware the only way to safely use a generator to backfeed your CU involves the use of a changeover switch.

I'm sure someone will be along shortly with more detailed warnings and informations!

EDIT - oops it seems they have already been along!

 

[redpis]

Thanks for taking the time to offer your advice.

I realise its a messy way and does introduce the possibility of error, so it looks like a changeover switch is the way to go!

Cheers

 

[ericmark]

Simple is often best. Select the circuit you want to connect to generator and put it on a plug. Install a socket next to plug connected to mains supply. When changing over un-plug from one socket and plug into generator socket.

This is simple method my son is adopting. At rear of boat three sockets.
1) Connected to shore supply.
2) Connected to inverter.
3) Connected to cable running to front of boat so if he comes in bow first he can connect power that end.

Yes walk through Turkey or any other country where they have regular power cuts and you will see rolled up on the generator in front of shops leads with two plugs. However they also have cars without seat belts, lack of hand rails and many other items which we would not allow in UK.

I am not sure about the whole idea of interruptibile power. We installed a large battery backed unit in the Falklands with semi-conductor switching which had three supplies. A three phase supply which charged batteries and could maintain output. An independent single phase supply in case unit failed and of course the batteries. But when the semi-conductor switch failed all power was still lost and after 2 years when the records were checked there had been more power failures due to UPS failure than generator failure.

If lighting is problem then use emergency lights. If fridge / freezer is problem then just use extension lead and plug into generator. Try connecting a 2.2KVa generator to a 32A ring and likely some one will at some time switch something on which either trips generator or causes fuel consumption to raise so it runs out of fuel and stops.

 

[ccam108]

DO NOT whatever you do do what my friend does.

13A plug-13A plug, in 1.5mm T&E, plugs in to socket in garage with main switch in the CU off. This kind of set up is safe when plugged in and in use but if someone were to unplug from garage socket, or switch on the main switch...

Colin C

 

[plugwash]

I am not sure about the whole idea of interruptibile power. We installed a large battery backed unit in the Falklands with semi-conductor switching which had three supplies. A three phase supply which charged batteries and could maintain output. An independent single phase supply in case unit failed and of course the batteries. But when the semi-conductor switch failed all power was still lost and after 2 years when the records were checked there had been more power failures due to UPS failure than generator failure.

Afaict the main purpose of a UPS is to provide continuity over the time between the mains failing and the generators coming on-line. Afaict a standby generator alone will start quickly enough to keep computers going without interruption.