Back up generator on domestic

[growler]

A customer has asked me to connect his back up generator 'properly' as currently he just flicks the main switch and plugs straight into the down stairs ring main.
I admit I have little experience with this and won't take it on unless I'm 100% I'm doing it correctly. It's a 5.5kva generator on a tt.
Can somebody help me with what I need to consider ?
So far I'm thinking
- change over switch
- earth electrode

 

[Lighthouse Phil]

Here we go.
1) your change over switch MUST disconnect Phase/ neutral AND EARTH from your DNO supply
2) Install an earth rod or mat connected to the frame of the genny
3) Link Neutral and Earth in the alternator
4) Unless the alternator has a method of maintaining the correct voltage / frequency, ie an AVR, do not connect any electronic equipment to the output

 

[PEG]

I will give you two other bits of advice,free. 1) your geny is of the wrong type and undersize, 2) Your customer will not pay what you will require to do it properly.....the distance between using the ubiquitous double plug top lead,and the correct system,is about the price of a month cruise to somewhere expensive...bon appetit

 

[johnboy6083]

I personally wouldn't worry about disconnecting the earth, as you're always going to have inadvertent connections via bonding, CPC's and the general mass of earth, between your genny rod, and the DNO earth. In this instance, being a TT system, you needn't disconnect the earth anyway.

 

[HandySparks]

I will give you two other bits of advice,free. 1) your geny is of the wrong type and undersize, 2) Your customer will not pay what you will require to do it properly.....the distance between using the ubiquitous double plug top lead,and the correct system,is about the price of a month cruise to somewhere expensive...bon appetit

Would you care to expand on any of this?

How do you know what type of generator the OP's customer has?
Why do you say that 5.5KVA is too low for domestic backup?
Since the earthing is TT and is likely to already have adequate RCD earth fault protection, why should doing it properly cost the price of a month's cruise?

 

[Engineer54]

Here we go.
1) your change over switch MUST disconnect Phase/ neutral AND EARTH from your DNO supply
2) Install an earth rod or mat connected to the frame of the genny
3) Link Neutral and Earth in the alternator
4) Unless the alternator has a method of maintaining the correct voltage / frequency, ie an AVR, do not connect any electronic equipment to the output

Why would you need to disconnect the DNO earth, come to that,...how would you??

 

[Knobhead]

You can’t rely on the DNO earth as work could be ongoing on the LV system. But as this is TT it’s not a problem.
As Phil has said a positive change over is needed for both L&N.
Linking N&E makes the installation when running on the generator TN-S.

 

[Lighthouse Phil]

Why would you need to disconnect the DNO earth, come to that,...how would you??

During a power outage, you cannot assume the DNO's earth is intact or your own earth rod. Theres also the possibility that the genny will send a voltage down the DNO earth.
The 2poles and earth go to the 'Mains' side of the change over switch / contactor before going to the DB.

- - - Updated - - -

You beat me to it Tony

 

[Engineer54]

During a power outage, you cannot assume the DNO's earth is intact or your own earth rod. Theres also the possibility that the genny will send a voltage down the DNO earth.
The 2poles and earth go to the 'Mains' side of the change over switch / contactor before going to the DB.

- - - Updated - - -

You beat me to it Tony

What are you saying, ...that a 3 pole C/O switch is needed for a single phase supply??

 

[growler]

Should I be running a 2.5 from generator to change over switch and connecting the generator via a 16amp socket ?

 

[growler]

Anybody ? Xx

 

[growler]

I'm not sure what's more dangerous, me connecting up generators or customer continuing to connect generator via 3pin plug straight into the ring main ..

 

[micknew]

I'm not sure what's more dangerous, me connecting up generators or customer continuing to connect generator via 3pin plug straight into the ring main ..

If you not qualified then both options have the same potential danger.
Get a professional in.

 

[growler]

I'll just wack in some 2.5 on an external socket for him to plug into and ride off on me horse.

 

[micknew]

I'll just wack in some 2.5 on an external socket for him to plug into and ride off on me horse.

Another DiIYer pretending to be a sparks!