Any reason I can't install an RCD on a generator.

The Continental Op · 29-10-2022 3:17pm #1

I've just found an old but brand new MEM combined 13Amp socket and RCD.

Is there any reason I can't install this as a replacement for a double socket on a 3KVA generator, obviously I'd only end up with one socket.

It was just a way to use it rather than stick it back in the box and loose it for another 20 years.

My only hesitation is that the generator output might be "dirty" and trip the RCD?

kirk. · 29-10-2022 4:15pm

What type of generator

AFAIK an RCD won't operate on some Genny's

The Continental Op · 29-10-2022 4:18pm

https://www.boards.ie/discussion/comment/119808870#Comment_119808870

That whats in the back of my mind ;-) I think I'll probably not bother as its a cheap chinese genny with a fake CE cert.

kirk. · 29-10-2022 4:59pm

Pressing the test button wouldn't confirm correct operation either afaik as it's only operating on the live poles and not the fault path if any

You would need to simulate a fault

The Continental Op · 29-10-2022 6:26pm

I'll probably give it a try just need to wait for a bit of better weather to do it as is stored outside.

iwillhtfu · 29-10-2022 6:36pm

https://www.boards.ie/discussion/comment/119808877#Comment_119808877

Technically its not fake but misleading. Their CE stands for China Export or something along those lines.

I don't see why you couldn't Install an rcd on it gen sets covering buildings everyday with rcds

kirk. · 29-10-2022 7:17pm

https://www.boards.ie/discussion/comment/119809387#Comment_119809387

https://www.boards.ie/discussion/comment/119809341#Comment_119809341

Think it's the inverter type the issue is with cos of the earthing setup

kirk. · 29-10-2022 7:31pm

Pressing test button conforms that the RCD does indeed work properly

Then in the event of an insulation fault for example you might find nothing will happen at all as there's no fault path.Cant say I know too much about them always seems such a complex subject generator hookups

10-10-20 · 01-11-2022 10:45pm

Isn't part of the issue with cheap gennys that the live and neutral are just 110v AC out of phase by 90 degrees anyway (giving 220v AC when measured), and the synchronisation between both gets thrown by switched loads, causing any RCD to read a delta between the "L" and "N", tripping the RCD...?

kirk. · 01-11-2022 10:50pm

I'd say any REC would just just fit a 2 pole changeover and plug and no more

Whatevers plugged in after that seems to be a minefield

These are "portable" generators after all designed to supply an item of equipment

02-11-2022 12:07am

https://www.boards.ie/discussion/comment/119821915#Comment_119821915

If the two phases were 110V and were 90 degrees apart then the voltage between there would be 156 volts (pythagorean theorem).

If 90 degrees apart to start with they are out of sync

The issue with cheap generators is poor voltage regulation and a very ragged waveform.

10-10-20 · 02-11-2022 7:30am

https://www.boards.ie/discussion/comment/119822092#Comment_119822092

180 degrees then.

monseiur · 02-11-2022 10:34am

Not wishing to hi jack thread and not an a electrician but can I ask a genny related safety question which may very well be a stupid question ! I understand that the earth cable is a critical part of house wiring - I'm curious to find out how a, say, 5KVA portable generator is earthed, in the event of a fault what happens when there's no direct path to earth ?

02-11-2022 2:06pm

https://www.boards.ie/discussion/comment/119822353#Comment_119822353

Then you have a generator that provides 220 volts between the phases that are 180 degrees apart. This angle will not change regardless of the load. It is fixed due to the placement of the stator coils.

What can change is the phase angle between the current and the voltage. This will depend on the reactance of the load.

kirk. · 04-11-2022 8:46am

https://www.boards.ie/discussion/comment/119822923#Comment_119822923

If there's no direct path through a wire or ground through rods nothing happens in a fault situation ,no MCB or RCD trips

The danger arises when there's 2 faults and they're both accessible, not a very likely scenario

The Continental Op · 04-11-2022 9:34am

https://www.boards.ie/discussion/comment/119831564#Comment_119831564

Not sure what you mean there? If there is no earth and you short out a cable (edit) to earth that is connected to a RCCB then there will be an imbalance in the current between the live and neutral and the RCCB will trip. The reason for me thinking about attaching an RCCB device to my generator.

Bruthal. · 04-11-2022 6:58pm

Many assume any live cable in contact with earth will involve current flow. If you sit a car battery on a table and connect it's positive terminal to the ground, how much current will flow?

The Continental Op · 04-11-2022 8:09pm

https://www.boards.ie/discussion/comment/119834164#Comment_119834164

If no current flows your in no danger then.

kirk. · 05-11-2022 10:09am

https://www.boards.ie/discussion/comment/119834466#Comment_119834466

2 faults and you could be electrocuted

You could have 1 fault on pipework a water pump for example and a later fault develops anywhere else on a metal appliance

kirk. · 05-11-2022 10:16am

There's probably less risk now because there's mostly plastic appliances and plastic pipework

Earthing and protective devices clear faults otherwise there's a hazard

Can't say I know too much it's a complicated subject earthing and generator hookups

10-11-2022 4:32pm

It is quite common on ships not to have any earth reference

The Continental Op · 10-11-2022 5:46pm

https://www.boards.ie/discussion/comment/119858121#Comment_119858121

Why would you bother when the whole metal structure is earthed?

btw sorry still haven't got around to testing the RCD socket yet :-(

10-11-2022 6:01pm

https://www.boards.ie/discussion/comment/119858419#Comment_119858419

To give the electrical system an earth reference.

Any reason I can't install an RCD on a generator.

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