Backup generator

[Lazlo]

Customer has already acquired a 'Loncin 80000-F' 6kW generator which has 115V and 230V sockets, to be used to run a few lights and central heating in power cuts. They are T-T. Genny also has a circuit breaker of sorts.

I'm suspecting it is not suitable as it will have a floating earth, chassis connected to the center point of the winding, meaning it will need double pole protection. Would it be acceptable to attach an earth electrode to the chassis then take the supply from the genny into an enclosure where the earth and neutral are linked and then Live & Neutral passed though an RCD, then a suitable MCB, then take the supply into a manual changeover switch?

 

[Engineer54]

Not being funny but I think you would be better to be passing this job on to someone that knows a bit more than you when it comes to domestic stand-by generators and their requirements. All is not quite as simple as it may first look....

 

[Marvo]

This type of genny is not for use as a permanently wired back-up power solution in a building. Just use it as it was intended by running extension leads, don't connect it to a DB or consumer unit.

 

[ferg]

I don't know enough about gennies to install backup gennies for domestics so when asked I decline the job or give Marvo's advice.

Chances are that any genny the customer supplies for a domestic won't be suitable anyway.

 

[Lazlo]

Yes, agreed. I've turned the job down and pointed them towards a company that supply and install generators. Stick to what you know and do it properly. Cheers for the advice anyway. Might be something I would consider doing some training for as I do get quite a few customers asking me. Does anyone know of a decent training provider for something like this?

 

[ferg]

Every customer I've had ask me about this has gone white at the cost of doing it properly.

I just make sure they know the dangers of a diy bodge.

Killing DNO jointers and other minor inconveniences.

 

[Simon-0116]

Obviously you need change over switch, 3 pole for 1 ph. Ie live, neutral, earth switched through. Earth changes over to a earth rod. Is that right

 

[Engineer54]

Obviously you need change over switch, 3 pole for 1 ph. Ie live, neutral, earth switched through. Earth changes over to a earth rod. Is that right

No, is the simple answer!! lol!!

 

[Knobhead]

Killing DNO jointers and other minor inconveniences.

^^^ Heed what Ferg has said ^^^

As a cable jointer trained by one of the old regional boards it was constantly drummed to us about the dangers of back feeds from badly installed generators.

Get it wrong and you’ll have the death of some innocent just doing their job.

 

[Knobhead]

Obviously you need change over switch, 3 pole for 1 ph. Ie live, neutral, earth switched through. Earth changes over to a earth rod. Is that right

It’s quite obvious you haven’t a clue what you’re talking about.

 

[Simon-0116]

So what do you need then

 

[richy3333]

So what do you need then

They won't tell you. Helpfulness isn't the point of this forum. Have your not learnt that after 80+ posts?!

 

[Simon-0116]

I know just the firm i used to work for many moons ago 4 pole change over switch on 3 ph and a earth rod on genny on. Tncs supply. Thats how we did it. Never questioned it as i was learning. Just asking.

 

[Engineer54]

I know just the firm i used to work for many moons ago 4 pole change over switch on 3 ph and a earth rod on genny on. Tncs supply. Thats how we did it. Never questioned it as i was learning. Just asking.

No again, it would have been a 4 pole 3 phase and ''NEUTRAL'' changeover switch!! the very last thing you would do, is leave a solid neutral connection between the main supply and a generator.

Perhaps this is one reason for not giving too much information out on a forum that could ultimately injure or worse others working on the DNO's distribution system... But don't tell richy3333 that, let him go on believing what he want to believe!!

 

[davesparks]

So what do you need then

You can't just put a switch in to the earth without it being guaranteed to make the earth connection first and break it last.

 

[Engineer54]

You can't just put a switch in to the earth without it being guaranteed to make the earth connection first and break it last.

It would do if as he stated he used a 4 pole changeover switch and used the usually marked N pole to connect the earth conductor!!! But then that leaves a solid neutral connection between primary and generator supplies... Not a very clever thing to do at all ...lol!!

 

[TJ Anderson]

Briggs & Stratton Power BST 9200M Transfer Switch | Just Generators

 

[Simon-0116]

No it would have been 4 pole . 3ph + n change over and earth rod on gen. So do they do a 5 pole change over that connects / breaks earth first /last. Asked at wholesalers today out of intrest and they said not. Never seen only 4 or 3.

 

[Knobhead]

Customer has already acquired a 'Loncin 80000-F' 6kW generator which has 115V and 230V sockets, to be used to run a few lights and central heating in power cuts. They are T-T. Genny also has a circuit breaker of sorts.

I'm suspecting it is not suitable as it will have a floating earth, chassis connected to the center point of the winding, meaning it will need double pole protection. Would it be acceptable to attach an earth electrode to the chassis then take the supply from the genny into an enclosure where the earth and neutral are linked and then Live & Neutral passed though an RCD, then a suitable MCB, then take the supply into a manual changeover switch?

You are absolutly right.

 

[Engineer54]

No it would have been 4 pole . 3ph + n change over and earth rod on gen. So do they do a 5 pole change over that connects / breaks earth first /last. Asked at wholesalers today out of intrest and they said not. Never seen, only 4 or 3.

That's because there isn't any, not unless it's to a special order, but you certainly wouldn't be switching the earthing through a changeover switch on a generator set-up anyway....

 

[D Skelton]

The mind boggles!!!

I don't think I've read a thread full of such epic fail as this one!


Now, to the OP; Lazlo, at least you have the sense to recognise your limit of knowledge and pass on the job. Why not post your location and someone on here might be able to help you with the work.

 

[Rockingit]

Unless I'm completely misunderstanding the OP, then I'm thinking that peeps have jumped to a wrong conclusion here. He says the install is TT already, so to my mind as long as genset is also TT'd outside the zone of influence then we don't need to worry about earth make/break, surely, which is then where using a 3p or 4p changeover device to also make/break Neutral with the phase/s comes in.

Or do I need another coffee?

 

[D Skelton]

Unless I'm completely misunderstanding the OP, then I'm thinking that peeps have jumped to a wrong conclusion here. He says the install is TT already, so to my mind as long as genset is also TT'd outside the zone of influence then we don't need to worry about earth make/break, surely, which is then where using a 3p or 4p changeover device to also make/break Neutral with the phase/s comes in.

Or do I need another coffee?

The OP was way out with other issues but recognises this. The issue isn't with Lazlo, it's with other melts that piped up with solutions even though they don't have the foggiest idea what they're talking about.

 

[Marvo]

These domestic generator threads give me the shivers. There's so many cheap 'site/camping' type generators that sound like they're being sold as fit for domestic back-up purposes. These things really should be divided into classes of configuration/suitability and they should be legally enforced to indicate the class on the actual generator and also they should be forced to supply a complete winding/wiring schematic on the genny itself and in the literature.

 

[Knobhead]

I don’t believe this! Marvo gets another like and thanks!

Generators should be clearly marked as “unsuitable for domestic use”. The really bad thing is the number of so called “electricians” that can’t/won’t see the problems.

To his credit he OP did raise his doubts about this.

 

[Marvo]

Agreed, the OP was quite rightfully expressing doubts, it wasn't his post that prompted my suggestion it was the multitude of generator connection threads we've already had.

 

[Engineer54]

To be honest, the generator the OP posted about would probably be suitable for a domestic installation if you knew how to safely deal the floating earth. It did at least come supplied with an AVR. It then comes down to the actual installation, and that's where many fall down i'm afraid...


What most people forget about, or should i say are just unaware of (and that goes for electricians and their customers) is that many of these small generators have limited recommended continuous running times, and the ongoing cost of the required regular maintenance. Virtually none will know or understand that running a generator at well below it's load rating is actually harmful to the drive engine.