Connecting a generator to essencial circuits

[spider]

Hi All,

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

Cheers

 

[mechelec]

You will need a changover switch in the tails to do this safely so there is no danger of running the mains and generator in parallel.
The local DNO will be knocking on your door if you put a backfeed on the mains when they are working on the supply cable

 

[Guest123]

Hi.

Got to say the "backfeed" idea just doesn't sit right with me at all.

I would suggest a mains changeover switch at the origin, then just leave the breakers for the circuits you want to run off it on.

No chance then, no matter how remote it may be, of energising mains and geney simultaneously.

 

[spider]

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

 

[mechelec]

Hi.

Got to say the "backfeed" idea just doesn't sit right with me at all.



You have good reason to be concerned about the backfeed onto the supply. A small generator would not have the power to backfeed a mains TX but if the cable was cut whilst being jointed it could give the jointers a nasty tickle!!!!!!!!

 

[Guest123]

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

I got to ask why join N+E???

Your geney will supply you with an simple TN-S supply as N+E will be joined in the star point of the geney winding.

All you need to do is install a rod next to the geney and connect to the gen frame (think of it as bonding if you like) although not really bonding, as it wont be part of the fault path unless the earth conductor in th TN-S goes open circuit.


Cheers.

 

[spider]

I got to ask why join N+E???

Your geney will supply you with an simple TN-S supply as N+E will be joined in the star point of the geney winding.

All you need to do is install a rod next to the geney and connect to the gen frame (think of it as bonding if you like) although not really bonding, as it wont be part of the fault path unless the earth conductor in th TN-S goes open circuit.


Cheers.

Yes I see what you mean , I will confirm tomorrow that the star point is connected to the body of the genny as that will remove the issue.

Refering to transfer switch data it recommends doing this modification, (however it is based on a floating earth) Power Transfer Switch

Cheers

 

[Guest123]

What they are saying there I believe is loosely based loosely on the EEBADS protection method and as you rightly say is based on a floating earth.

If they are strapped at the alternator then this would negate the need for it to be done in the plug and also negate the need for the rod as the fault would be cleared by the RCD protection in the geney.

 

[UNG]

What I was thinking is to install a Gewiss GW66004 switched socket oulet 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)

I would have concerns over a modified plug into a socket arrangement

As mentioned the system should use a changeover switch and a mains inlet like the type that are fitted to caravans

 

[Darkwood]

You could got an extremely large loan out and fit an automatic change-over unit which brings the gen' on when powers out but when power returns it waits till its frequency cycle matches the mains before doing an uninterupted change over.Tie all this in with a seperate consumer unit with Heating, Alarm, Fridge etc on it and you got everything covered even when your away.

 

[spider]

You could got an extremely large loan out and fit an automatic change-over unit which brings the gen' on when powers out but when power returns it waits till its frequency cycle matches the mains before doing an uninterupted change over.Tie all this in with a seperate consumer unit with Heating, Alarm, Fridge etc on it and you got everything covered even when your away.

The wife thinks I'm nuts anyway, we have never had an outage over 2hrs since we have lived here (3 years), she thinks I'm being disproportionate, a bloke, never lol

(do like the idea of an auto start genny though)

Cheers & hapy xmas

 

[Darkwood]

The wife thinks I'm nuts anyway, we have never had an outage over 2hrs since we have lived here (3 years), she thinks I'm being disproportionate, a bloke, never lol

(do like the idea of an auto start genny though)

Cheers & hapy xmas

Just compare your cost and time for your project to her make-up box and its yearly cost and im sure you will win the argument hands down, but dont bring in the no' pairs of shoes she has to have and the different outfits for each pair as this is only to win the argument and not to lose the wife.

 

[mechelec]

I got to ask why join N+E???

Your geney will supply you with an simple TN-S supply as N+E will be joined in the star point of the geney winding.



Not always.Many generators run an "electrically seperate" earth system where the neutral point of the windings is connected to the neutral of the socket and the frame is bonded to the generator body only. Do a continuity test between the neutral in the socket to the frame and you will find most small gennies are seperate. If you want an RCD to operate then as previously stated the neutral and earth will need to be connected.

 

[cbw]

I am in a similar situation, we live in a very rural area and often lose our power.

I have a small 1kw generator in my shed, this has an earth spike to it case, an rcd in the front of it and this then runs a long extension lead which powers tv/dvd/sky, 1 low energy bulb in each room, telephone and most importantly the boiler controls(oil fired) which gives us heating and hot water.

It is just a 'make do' but it keeps us warm and lit.......also the elderly neighbours!

 

[spider]

Looks like my wish list for santa includes one of these, at £89.00 not bad (would like the gucci Briggs Stratton jobbie but need more overtime).

So all I have to do now is sort out how to get the incoming MEM isolator seals opened and re-sealed afterwards ( strange that its sealed on the consumer side after its been metered), looks like I'll be on the phone to my DNO for a while

Found a place for £75.40, now her indoors must be happy!