230v Generator used for domestic , basic help

[vde-electrician]

just want to clear a few things up:

intend to use a generator on a domestic using a manual change over switch (basically if the electricity goes off)

my questions:

1) if generator has floating earth (neutral and earth not connected together), can i rod/spike the generator frame and connect this to the domestic earth to become invariably a TT?

2) if the generator is not floating (n/e connected together) , can this be treated similar to a TNCS (pme) and then just bond the gen frame (without the use of a rod) and have the earth/neutral seperated in the consumer unit?

3) how do you treat in the existing main earth e.g. TN system into the property when usnig a generator, unsafe to disconnect?

any help would be much appreciated, asked a few other local electricians - people seem to be unsure as they don't tend to install them much round my area, or they don't 100 percent know what is truelly correct.

*With the above, i understand the generator supply cable has to be correctly installed / rcd protected possibly/ fused correctly

thank you

 

[davesparks]

A generator with a floating output would be an IT system, not TT. And the vast majority of such generators will write off anything electronic connected to the output.

A generator with a N-E link gives you a TN-S supply and requires an earth reference via an earth electrode. It would be prudent to install RCD protection as you will not achieve disconnection times otherwise

 

[Richard Burns]

A floating earth would be a very inadvisable method of supplying a house, notwithstanding Davesparks comments about the suitability of the generator itself, and would only be allowed when under controlled circumstances.

Using the TNS supply with an earthed neutral the neutral should be separated at the first opportunity i.e. the primary over current protective device.

It is not permissible to use the suppliers earth for a generating set operated instead of the normal supply, it must be disconnected from your generating set and you must supply a suitable earthing system for your generator.

In all instances for a standalone generator it is necessary to ensure that your generator cannot introduce fault current onto the public supply or otherwise interfere with the public supply.

 

[Lucien Nunes]

A generator with a floating output would be an IT system

A floating earth would be a very inadvisable method of supplying a house,

Indeed. It will dramatically reduce the likelihood of RCDs successfully detecting and disconnecting a fault, for a start. OK for single loads, not for general installations with their risk of multiple faults and leakage paths.

the vast majority of such generators will write off anything electronic connected to the output.

This intrigues me, as I'm not sure why it would be so, and it doesn't tally with my experience. Please you could clarify?