generator supply to garage

[dunaird]

Due to frequent power cuts I intend to use an existing 2.5kw generator to give back up supply to fridge and freezers in garage.

I can isolate the mains supply from CU to garage and re-route via a 2 pole changeover switch however, what about the earth.

Can I safely rely on the existing mains earthing or do I need to instal a new earth from the genny and if so, does the genny need an earthing rod? Advice please!

 

[f42]

Earth Spike at genny,

mains powercut maybe due to cut cables which could leave you without an earth.

 

[ericmark]

Earth Spike at genny,

mains powercut maybe due to cut cables which could leave you without an earth.

I would agree. What is to be considered is should one switch an earth? In past I have only used generator for some of the functions not all and used a two sockets and plug arrangement so there is no way any of the cables line, neutral or earth can be connected together between both supplies.

 

[big-all]

even allowing for start up loads your fridge freezer and lights will be hard pushed to use 750w so would have thought 1kw would be more than enough
having said that if you cover your freezer and the fridge with a quilt and don't open the doors the fridge will be ok for a few hours and the freezer for around 24 hours

when my last freezer failed i opened it once a day to remove day one fish day 2 pork and chicken day three any meat products i condenced the contents down and covered with a quilt it still has ice/slush after 6 days so was still below the 5 degrees you would get in a fridge so keeping the food safe
obviously if the teperature rises above -5 you have to eat the contents within a week or so

what people dont realise is this often happens on frost free fridge freezers when the freezer internal temperature is raised close to zero in the defrost cycle when the ducting is heated at the back to melt the ice build up and that goes on for about 20 hrs not only no freezing but heat behind

 

[f42]

Line and Neutral should be switched via a changeover switch however the earth doesn't matter. In this sort of installation it is often seen with two main earths present in the garage/outbuilding CU ( One from the grid and one from the earth spike near the genny)

 

[Lectrician]

Depending on the generator, you may also need to link the neutral and earth.

Even linking the neutral and earth, you still do not need to switch the earth, as you are switching the neutral.

If the generator is a plug in type, where this NE link goes is debatable.

Search this forum for generators - it has been debated and spoken about many, many, many times!

 

[ban-all-sheds]

If the generator is a plug in type, where this NE link goes is debatable.

Doesn't it depend on whether you want your generator to provide a TT/TN-S/TN-C-S supply?

(meters & cutouts etc omitted for simplicity)

 

[dunaird]

Many thanks all who responded.
Will earth as for TN-C-S installation which I have and link NE at enclosure with changeover switch.
Many thanks 'ban-all-sheds' for schematics
'dunaird'