Earth rod for back up genny

[LastManOnline]

Hi folks,
installing back up gennys not my thing.Cant avoid this one though.Have looked through previous threads.Two things still not entirely clear for me are...

1) Are there any reasons why the homes existing earth electrode wont suffice?

2) If a separate rod is required ,what would be the recommended max. resistance?

Thx in advance

 

[James]

If the property has its own earth, it is likely to be sufficient.
you can’t rely on the suppliers earth, as it may well be disconnected during a power cut.

 

[Rockingit]

The requirements are for both the set to be grounded, and for that grounding to be carried over into the installation's MET. Therefore, if the property installation is already a TT with its own rod, then assuming that rod is actually fit for purpose with a respectable Ra then it can almost certainly be used. That being said, you need to pay attention to your isolation/switchover between one energy source and the other.

 

[LastManOnline]

then assuming that rod is actually fit for purpose with a respectable Ra then it can almost certainly be used.

Thx guys.What would you regard as a "respectable Ra"?

 

[Rockingit]

Thx guys.What would you regard as a "respectable Ra"?

This is where things can get interesting! Conventional wisdom says that anything over 200Ω isn't really worth much, despite the magical max number of 1667, hence why you need upfront RCD protection (again, conventionally either 100mA 's' type or by individual RCBO's). However.... the genset itself may well have a 'standard' 30mA RCD / 16 or 32A MCB (you don't mention the size of the set so I'm assuming small domestic / builders style) so that then gives you difficulties with discrimination. However (part B..) if you change that upfront OCPD to be something more suitable (say a 300mA 1s device) then you might fall foul of the need to protect the feed cable from the set to the property at 30mA unless you're prepared to accept that you'll be running out SWA, eg.

Whilst we're at it.... if it IS a smaller set then you'll need to refer to manufacturers info re the nature of it's Earth as it's most likely 'floating' and you'll need to create a PEN link at the set as well.

 

[LastManOnline]

This is where things can get interesting!

Interesting!!well that about sums up the project so far.

Genset is a "Pramac p6000".
The owner got no instruction manual.
The dealer has not responded to my emails (3 in total) since 20/12/22.
The Pramac website does not currently have a technical helpline.Its "under maintenance".
Pramac utube videos are general information,not technical.
The manuals I,ve accessed so far had little to nothing in the way of specific guidance on earthing arrangements.
The only specific info I found was on their main site.It stated regarding pramac portable generators that "do not need to be grounded"?? No further explanation given.

Make of that what you will.
I,ll be back.