230 Generator poweringfuseboard & earthing

[aaelectric]

Hi

I've been asked to fit a 10kva generator to supply a 17th edition fuse board.
The problem I'm having is when i test for my ze from live to earth i get 28v but from neutral to earth i get 230v. I thought i had reversed polarity so i swapped the live and neutral over at the main switch in the fuse board, but it made no difference and the same happened again. I have fitted an earth spike connected to the earthing terminal on the generator and have a 32 amp commando socket connected. I tried to take a reading for my ze but the frequency from generator is 255hz and my tester ( megga 1720 ) will not let me as the hz is over 50 hz. The two rcds both trip on the test buttons but cannot get a millisecond reading. I have left the existing earth of the tns cable coming in connected as it is still feeding the flat above the shop. Any advice on this and why i would be getting 230 between neutral and earth. If i turn the main switch off at the fuse board between live and earth i get 110 v and between neutral and earth i get 110 v but as soon. As i turn the power on I don't get any voltage between live and earth. This is my first generator installation, any advice welcome

 

[Knobhead]

Have you earthed the neutral at the generator? Have you fitted a DP centre OFF change over to the generator supply and the DNO supply?

 

[aaelectric]

Hi tony
no i have not connected neutral to earth link, where would i put that? On the commando.also what is a dp? There is a 40 amp mcb on generator and it goes into main double pole switch on fuseboard.

 

[Knobhead]

Hang on a few minuets I've got a drawing for you. Got to upload it to host.
The neutral should be earthed at the generator, it's you're source of supply. A double pole centre off switch should break the DNO’s supply before the generator connects. This is to prevent back feeding in to the distribution system. Get it wrong and you could end up killing someone working to repair the system. a commando is not a form of isolation / change over.

 

[Knobhead]

Here you go

 

[aaelectric]

Tony there is no supply from dno as this has been dissconnected from main fuse at head but there is another flat with afuse which is still working. Tails have been taken out of main switch at fuseboard on thing connected is earth at earth bar in fuseboard connecting all bonding and main earth on supply cable. Should this be dissconnected?

 

[Knobhead]

You can not use the DNO earth as a generator earth. You're going to end up killing some poor lecky board guy!

 

[aaelectric]

Iv put an earth rod in but carnt get a reading as hz are high
does this have a floating earth? Should this be dissconnected from fuseboard then what about bonding.?
should i connect neutral & earth in commando?

 

[Knobhead]

You DO NOT connect the N>E in the commando! Whats the earth rod conected to? It should be at the generator direct to the neutral. Look in the Flamin REG's

 

[Marvo]

Can you give the make and model number of the generator you're working with. Some of the smaller generators aren't suitable for using as a supply in a domestic premises because they're wired internally to a V-O-V scheme which means you can't bond neutral and earth.

 

[Knobhead]

Good point, I'll leave you to explain why he needs a DP board if it is.

 

[Marvo]

Thanks Tony I'd rather suggest he abandons the project before someone gets hurt. It should be completely illegal to use site gennys as domestic supplies. Apart from the safety implications the power quality is usually atrocious.

 

[aaelectric]

HSS Hire - 10kVA Silenced Diesel Generator Hire and Rent
This is the gennie the earth rod is connected direct to earth point on generator which is connected to the metal work of generator.

 

[Marvo]

Looking at the pdf here the genny supplies both 115v and 230v. This suggests to me it is in fact going to be VOV configured and will not be suitable for using as a domestic dwelling power source. I would consult with either the manufacturers or the suppliers to confirm the winding arrangement before you go any further with this.

 

[Knobhead]

Best of luck kid, you'll need it!