Generator N/E link

[ban-all-sheds]

If I've got a generator connected to my house via an IEC309 plug (and a proper BBM changeover switch..), and I want to link N&E, if I don't want to modify the connecting cable is there any reason why I shouldn't put the N/E link in the socket in the house that the cable plugs into?

 

[JohnD]

I know nothing but

you are forbidden to link N&E within the installation - it can only be done upstream of the meter by the supplier. i think this was in the Electricity Act but may be wrong.

Why don't you link them at the generator? You will need an earth spike too, as you cant rely on the supplier's earth when you are not using their supply.

p.s. obviously you have the socket connected to your generator, not the plug?

p.p.s. welcome back

 

[ban-all-sheds]

Don't want to modify the genny.

So I can put the link in the plug at the genny end, or the plug at the house end, or the socket at the house end - right now I'm struggling to see what the difference would be, once the cable is plugged in.

And when it is I'd be disconnected from the public supply, and when it's not then the changeover switch would isolate the N/E link, so I wouldn't have one within my installation.

Thanks re earth rod - I will have one, just hadn't mentioned it. Actually I might have a 20m long piece of tape in a trench instead...

PS - ah - plugs/sockets - how does one decide what to call each? Is it just the M/F attribute that decides, i.e. is a receptacle on the wall with male pins a plug?

 

[djrichie_t]

Put a n/e link in the plug that goes into the genny and you will be fine. What you can also do is make a very short lead especially for that purpose, especially marked 'neutral/earth linking lead' which means that you can use any normal lead to go from the genny into your house, and plug it into the special short lead that will provide the link.

There should be an earth screw on the genny which will let you connect to earth rod, if not then tee off with a piece of earth wire from the earth pin of the link plug that goes into the genny.

 

[Spark123]

The only logical reason I can think why you would have the N/E link at the generator end as opposed to the house end is in case the cable becomes damaged and you lose your CNE conductor. A N/E link at the house end will cause the CPC to rise in potential to the same as the neutral (which in an open circuit neutral isn't nice) and depending where the electrode is in the equation, with respect to earth too.

 

[ebee]

He Has Arisen!

PS the answer to the original question is yes.

 

[ban-all-sheds]

Earth electrode will be at the house end.

Take your point about the broken neutral, but this would be a temporary connection, thus regularly inspected.

Food for thought though - thanks.

 

[bernardgreen]

You may need to consider the situation where a different generator is connected and that generator is wired as phase1--Neutral--phase2 (120--neutral--120 ) with its neutral strapped to the generator frame and hence earth.

A fixed link between domestic neutral to earth would be seen by the generator as a short between a phase and generator neutral via the earth.

Or if the generator frame was not earthed then the frame would be lifted to 120 volts above earth. The generator phase earthed in the house will force the floating generator neutral and frame up to 120 volts..

 

[djrichie_t]

Or if the generator frame was not earthed then the frame would be lifted to 120 volts above earth. The generator phase earthed in the house will force the floating generator neutral and frame up to 120 volts..

Yep I made that happen before, was quite interesting too! Sometimes on CTE switchable 110-240v generators this happens, Just undo the socket panel inside the genny and you will see the link, just remove it. Sometimes its made through a wirewound resistor.

When there was a power cut a local transmitting mast was giving off a power hum on all the radio stations as they used a generator, we had to go there to connect a bigger diesel genny and earthing the neutral stopped the hum.

 

[ebee]

If I've got a generator connected to my house via an IEC309 plug (and a proper BBM changeover switch..), and I want to link N&E, if I don't want to modify the connecting cable is there any reason why I shouldn't put the N/E link in the socket in the house that the cable plugs into?

Two concerns
1/ Is it possible that someone else might use this socket and be unaware of the link at any time in the (un) forseeable future.
2/ Is the gen earth a/ floating , b/ centre tapped.

 

[ban-all-sheds]

You may need to consider the situation where a different generator is connected and that generator is wired as phase1--Neutral--phase2 (120--neutral--120 ) with its neutral strapped to the generator frame and hence earth.

A fixed link between domestic neutral to earth would be seen by the generator as a short between a phase and generator neutral via the earth.

Or if the generator frame was not earthed then the frame would be lifted to 120 volts above earth. The generator phase earthed in the house will force the floating generator neutral and frame up to 120 volts..

Neither of those scenarios change if the N-E link is in the commando plug inserted into the generator output socket instead of in the socket in the house where the plug on the other end of the cable is inserted.

. . . . .

Two concerns
1/ Is it possible that someone else might use this socket and be unaware of the link at any time in the (un) forseeable future.

I wonder what else someone might do in the future with a male IEC-309 socket connected via a changeover switch to the upstream side of some of the circuits in my house....

And anyway - the warning label, just like the one I'd have on the plug of the cable if I put the link in there would alert them, no....

2/ Is the gen earth a/ floating , b/ centre tapped.

haven't got it yet, but probably (a).