Generator - Basics question.

[bathjobby]

Basic stuff I guess for you guys (hopefully).
If I get a portable generator with a 230v output on a 13 amp socket, if there was a mains power failure can I connect (using a correctly rated cable with a 13amp plug on either end) the generator into any socket on one of my ring mains to feed the appliances on that ring ? (putting aside the question of loading and generator output for the moment), and if so, what happens when the mains power is restored if the generator is still connected and running ?
Many thanks in advance....

 

[Pensdown]

I have seen that done but it's bloody dangerous because the pins on the plug are live. If its unplugged from the socket while the geny is running you get a handful of 240volts!

You must also turn off your mains switch at your CU. If the power comes on with your geny running.....bye bye geny

 

[bathjobby]

Thanks pensdown. Isn't the switch on the CU just on the live side ? so is that safe enough if the power were to come back on with the geny still running ?
And how do these home generator setups that push spare electricity back to the power stations work ?

 

[Plug]

DO NOT UNDER ANY CIRCUMSTANCES CREATE A CABLE WITH A PLUG ON BOTH ENDS.

This is obviously not the correct way to go about this, you would be massively cutting corners in terms of safety. If you make a cable with two plugs on it, anyone could come along and plug one end in and switch it on, and then electrocute themselves by touching the other end. It's all very well saying "only I'll use it", but the truth is, unless you keep it on your person at all times, you can't be sure that this is the case. If you consider the lives of those in your house to be worth keeping, you have to be insane to do this.

You suggest that this is a basic question. There is a basic answer: DON'T DO IT!!

 

[RF Lighting]

I beleive the proper term for a cable with a plug on both ends is a widdow maker. Kind of speaks for it's self. The only proper way to wire in a standby generator into your installation would be to use an all-poles change-over switch. So you can manually select either DNO supply OR generator supply (but not both at the same time. If you were to make up the lead you suggest and plug it in to a socket you would end up feeding all of you installation, and everyone olse on you street (on that phase). Also you might end up killing the man from the DNO who has turned off the power and is working on the other end of the cable.

DO NOT DO IT

 

[Adam_151]

I beleive the proper term for a cable with a plug on both ends is a widdow maker.

Someone reads the blue room

 

[bathjobby]

plug

This is obviously not the correct way to go about this, you would be massively cutting corners in terms of safety.

thanks, but it offers no information only emotion, hence my request for information on the 'basics' of this question.

RF lighting

The only proper way to wire in a standby generator into your installation would be to use an all-poles change-over switch. So you can manually select either DNO supply OR generator supply (but not both at the same time)

thanks for the 'information'.

 

[plugwash]

as pensdown says if you turn off the main switch and use a lead as you propose then it will work and it won't cause a hazard to those outside your house.

however there is a real risk of either the plug coming out leaving live metal exposed or the main switch getting turned on by acident (which at best means blown fuses and at worst killing DNO staff).

seriously if you wan't to run stuff off a generator during a power cut do it properly with a supply changeover switch. Its probablly a good idea to have a second CU for stuff you wan't to go on the generator.

e.g.

[code:1]
Meter
|
Existing CU--Circuits without backup power
|
Generator---Supply changeover switch
|
New CU
|
circuits with backup power
[/code:1]
(edit: i used the wrong tags for the diagram)

 

[Spark123]

Another thing to be aware of is normally small single phase generators deliver a supply which is not electrically bonded to earth, i.e. electrically separate hence the need to be bonded to earth (via an electrode) and the neutral linked to the earth before use with an EEBADS system. BTW I too read blue-room and I think you are right re widow-maker RF, they are frowned upon over there too. There is a thread ongoing re generator earthing which may be of interest.

 

[bathjobby]

plugwash, spark123, thanks. Thats the informative I was looking for rather than they 'eeerk, don't do it' with no information. Many thanks guys.

 

[Job_n_knock]

Oh my goodness the potential for death on this thread is serious.

I once heard of a woman who ran out of juice on her key meter on Xmas day. Her ignorant but helpful neighbour did exactly what was mentioned above....he made a lead with a plug on both ends and plugged into his socket, ran the cable out into the garden and across and into her house and plugged it into her socket. All was fine and she watched TV with her kids. Following day she went and got her key charged, got home, plugged it into her meter and the Meter relay closed down onto a 415V dead short and hospitalised her with serious burns.
When it comes down to playing with mains....only advice is to get a professional electrician period !!!

 

[Adam_151]

I once heard of a woman who ran out of juice on her key meter on Xmas day. Her ignorant but helpful neighbour did exactly what was mentioned above....he made a lead with a plug on both ends and plugged into his socket, ran the cable out into the garden and across and into her house and plugged it into her socket. All was fine and she watched TV with her kids. Following day she went and got her key charged, got home, plugged it into her meter and the Meter relay closed down onto a 415V dead short and hospitalised her with serious burns.

Daft , but I must say I'm supprised by the burns and stuff, What actually happened? did the contactor in the meter explode?

When it comes down to playing with mains....only advice is to get a professional electrician period !!!

why? electrics is not beyond the capacbilities of the properly competant and equipped DIYer[/quote]

 

[Job_n_knock]

why? electrics is not beyond the capacbilities of the properly competant and equipped DIYer

I appreciate that but here we are discussing the earthing arrangements of Generators etc. In my honest opinion the only level of competence is that of a trained individual otherwise they are incompetent.
When you get a dead short across 2 phases you can be damned sure that meter will not survive the flash and neither can you expect that woman's face to avoid burns when its less than a meter away.

 

[supersparky]

all depends on loop impendence

i know of a incident a few weeks ago where 3 phases were cut through in a micc cable

it dident short until there were enough filings within the cable to cause a short between L2 and neutral

Some numpty had put 100A BS88S at the supply head with no further protection on 4mm 4 core MICC and the earth loop was non existant P-N resistance was 1.2 ohms!

the cable had been prooved dead by splitting a joint before cutting but a previous tennent had rigged up time switches that bridged out the meter but only at times after a meter reader would turn up, most of their work was at night...wonder why

thankfully guy cutting the cable was using cordless insulated tools and wearing a full face visor and helmet

the place had been prooved dead by the rec after they removed and sealed their fuses

despite the protective gear there was hardly a bang and hardly a flash, the blade being used wasnt damaged at all when you would expect it to be melted

 

[SparkyMarky]

The other thing to bear in mind is the capacity of the ring circuit itself. Turning off the main switch would isolate the house from the mains supply, but it would not isolate the ring circuit from the other circuits in the house as they're all connected to the common busbar in the CU.

Unless you were very careful about switching off all other appliances in the house and making sure they stay switched off, you could end up supplying your cooker, immersion heater, electric shower etc. through a 13amp socket and your ring main (unless a breaker trips or fuse blows of course). Switching off the individual mcb or pulling the fuse from the CU for the ring main would stop this, but then you're breaking the ring which could lead to a whole load of new problems / considerations...