Genny dilemma

[D Skelton]

A customer has bought this as a back up generator for when his house power cuts out:



It's a £300 ebay jobbie, 220V/380V, 'supposedly' with AVR. It's rated at 6.5kVA at 380V and has a three pole C3 OCPD. I went to have a look this evening (I hadn't seen it beforehand) and tested for a floating earth which it has. I didn't get a chance to test it whilst running. There are no manufacturers instructions or specifications, no definite information on the winding layout, no information on anything at all, anywhere. I've been searching the interweb for hours!

If I'm honest I wouldn't trust this chang wang piece of crap as far as I could throw it and have told the customer in no uncertain terms that he really needs to think about sending it back and getting something fit for purpose. He's looking for reasons to ignore me! The problem is that if I don't help him out as best I can and he finds someone else, I'm almost certain I'll be missing out on a rather tasty barn conversion for him later in the year!

Wants me to just link the N-E at the supplied schuko plug and throw in a stake. I'm not happy at all! Not one bit!

Bit of background - the only experience I have had with gennys so far is for transportable units (catering wagons), I've never wired up a genny relying on ADS before. I get the N-E linking thus creating a TN-S of sorts, I get the referencing of the neutral point to true earth, I'm also happy with using 3 point (make 1 - off - make 2) changeover switch. What I'm not happy with is the thought of linking at the plug, nor am I happy with the genny.

Thoughts please?

 

[Guest111]

I've seen that genny before,last week there was a programme on tv about gypsy's that had taken over a village in Irealnd,anyway in summer they went to europe pulling various scams and one of them was selling that particular genny.The film makers got hold of one and got this french electrical engineer to have a look,he said at best they were useless and at worst dangerous.Maybe you should mention this to your client.

 

[timbobelfast]

I remember seeing that program to. Glorified paper weight springs to mind. Tell him it is not CE / EN approved therefore scrap.

 

[D Skelton]

Bump!

I need to get back to the customer today really, I'm scratching around for the best possible advice I could give him, in the nicest way that ensures I'll see future work from him.

Any help from you guys would be appreciated

 

[Marvo]

Persuade him to use it as it was intended. Just run a few extension leads around the house, if there's a power failure he must just start that piece kak and plug things into the leads.

 

[richy3333]

What make is the genny supposed to be? I'd be interested to see what instructions are available online?

 

[D Skelton]

It has no make and there are no instructions! It's some imported chang wang piece of garbage.

I've been in contact with the customer and he's happy for me to advise on a better option for connection to his home for backup purposes. His budget is £1500 - £2000.

I'm just trawling the web and can't find any supplied as standard without a floating earth. If this is my only option I guess my question now is; do I bodge a N-E link at the plug (don't like this idea one bit) or do I fit a N-E link at the genny potentially invaliating any warranty? Hondas look like the best option with their smooth supply but they're all floating systems!

Ideally I'd like to find a genny with its neutral bonded to earth as standard.

Any ideas?

 

[plugsandsparks]

Only thing I would do different is to contact a manufacturer say Honda, explain you want to use the genny where earth systems need to be tied etc and ask if the genny can be modified internally or if there is a kit they supply to do this. It cannot be the first time this requirement has come up and lets face it a floating earth is no good to connect to a house with all the class 1 stuff around and a gas pipe to worry about etc. BTW if you do get any joy from a genny manufacturer let us know cos I expect an increased demand with the weather and all

 

[D Skelton]

Guess I'll be phoning around next week!

 

[Richard Burns]

If the generator is solely to be used as a back up power supply for the house, then fitting a N-E Link at the generator is really the only option. Depending on the generator this should be a reasonably easy operation and preferably non destructive to the generator, the connection can be a screwed joint so long as it is easily maintainable so it could be removed if required. I do not see why a standard modification to a piece of equipment by a competent person should invalidate a warranty.

Have a search for BS7430 COP for earthing of electrical installations.

Even the supplied generator could be used if the earthing arrangements could be sorted out and you were sure of the "Pure sine wave" output and it had any form of standard to which it is made.
At least if you made modifications to that the warranty would be non existent anyway.

For earth bonded neutral you would, I think, probably be looking for fixed generating sets that would exceed your customers budget.

All that said I may well be talking rubbish anyway, but I do hope you mange to sort something to maintain the customer base.

 

[Robotstar5]

I'll be following the thread too, just got a Hyundai genny to run lighting at the stables.
I can recommend the suppliers Just Generators competetive prices, quick, well packed delivery.

 

[D Skelton]

I guess the only option then is to speak with the manufacturer regarding the warranty. The only gennys I see with pure sine wave output are at least £1k+. I know the Honda ones generate at DC and then rectify with an inverter giving a pure sine wave output, you can get these within budget, the only hurdle is the N-E link.

I'm not looking forward to phoning Honda though I must say!

 

[Marvo]

This is a common problem when a site generator is redeployed as a back-up generator when it was never designed for it. Is it legal in the UK to bond the N+E at the plug or socket? I'd agree with Richard above, bond internally in the genny as long as the winding arrangement allows for it, I also don't see why there should be warranty problems if it's done by a qualified person in order to comply with local regulations and even more so if the genny was sold as a home back-up solution.

 

[Richard Burns]

Thanks Marvo you reminded me of something: one recommendation was that you make up a lead that has the plug that fits to the generator with the NE bond.
In this way there is no wiring that is not earthed, but simply removing the plug returns the generator to floating earth.
However although this was recommended somewhere I am not sure of the legality, I cannot think if a problem with it but I could well be wrong.
The lead should obviously be marked up as not be used for anything on a standard fixed installation.

 

[D Skelton]

Is it legal in the UK to bond the N+E at the plug or socket?

I can't see how, that's my main gripe! In my mind you're essentially creating your own little TN-C-S at the genny end. As I said, I'm not a genny expert but it feels very wrong and unless told otherwise, I would never want to do it.

I'd agree with Richard above, bond internally in the genny as long as the winding arrangement allows for it, I also don't see why there should be warranty problems if it's done by a qualified person in order to comply with local regulations and even more so if the genny was sold as a home back-up solution.

You'd have thought wouldn't you? Who knows? The genny I'm now looking at is sold as a home back up solution. £999 for a diesel backup generator, still got a floating earth though! The retailler is even peddling this idea of adapting the plug!

 

[Marvo]

Yeah, regardless of regs, bonding N+E in the plug especially doesn't feel right to me. It also leaves the possibility that another lead could be used in future that doesn't have the link.

 

[D Skelton]

At least linking the two inside the machine means that I can attach a big fat sticky label telling people that this is the case.

 

[D Skelton]

This is the one I'm looking at:

Evopower EVO6000SELR 5.2kW 6.5kVA Diesel Generator | ThePowerSite

Looks like a reasonable bit of kit for the money!

 

[Marvo]

That looks much better and far more fit for purpose. You shouldn't have a problem bonding N+E on that one, I'd expect it to come with an option to do it as it's designed as home back-up.

 

[D Skelton]

Far better than that chang wang one he's already got! lol

 

[Marvo]

Hopefully he can get a refund?

 

[Richard Burns]

Hopefully he can get a refund?

From Ebay or China?!

Certainly the one above seems a better bet, I assume the customer does not need three phase supply.
Does it say anything about the voltage stabilisation, I assume because it is designed as a backup generator it would be suitable but can't see anything on a quick glance, probably in the manual.

 

[D Skelton]

From Ebay or China?!

Certainly the one above seems a better bet, I assume the customer does not need three phase supply.
Does it say anything about the voltage stabilisation, I assume because it is designed as a backup generator it would be suitable but can't see anything on a quick glance, probably in the manual.

Yeah, it comes with AVR as standard. No need for TP supply.

 

[Engineer54]

The EVOPOWER set looks to be the far better bet, it'll probably have a far better AVR and other components than the £300 jobby too. No harm in asking this Generator supply company their recommendations as far as earthing provision to this set. I wouldn't mind betting that they too start talking about N-E connections at the plug top as well though!! Just don't have of it though. The earth connection on the control panel faceplate will be for touch/static voltage only.

What type of C/O switch are you going for, MTS or ATS?? Me i always recommend ATS, but it is the more expensive option. I suppose it depends on how simple you/customer wants the system to be and how accessible the system is going to be, once located in place etc...

 

[D Skelton]

The genny will be located in an outhouse about 15m away from the main property. I've only specced MTS as power cuts are very infrequent but when they do happen they happen for days.

 

[GLENNSPARK]

Yeah, regardless of regs, bonding N+E in the plug especially doesn't feel right to me. It also leaves the possibility that another lead could be used in future that doesn't have the link.

it dont feel rite caus it aint rite...

what you will have created is a TN-C...not allowed in the UK...

 

[D Skelton]

TN-C-S PNB isn't it Glenn? Still, I'm pretty sure we shouldn't be creating this sort of supply!

 

[D Skelton]

Thinking about it, are we even doing that?? To do so would assume that a generator is the same as a DNO supply, which in every case will always have their star point referenced to earth. With this link removed it doesn't change the supply type does it, it just becomes dangerous. A generator provides an electrically seperate supply, linking the neutral to earth to not only reference to true ground but to provide a TN-S supply of sorts doesn't technically create a TN-C-S because the supply type doesn not conform with the norm anyway? That's my thinking. It still feels wrong though to bodge the N-E at the plug rather than in the genny.

 

[GLENNSPARK]

TN-C-S PNB isn't it Glenn? Still, I'm pretty sure we shouldn't be creating this sort of supply!

depends where the neutral-earth link is made

 

[plugsandsparks]

Safety Information It looks like the manufacturer advocates a special "plug" that is connected to the changeover switch which is then plugged into genny. The plug has the NE link. This way they say means the genny can still have a floating earth for pure mobile use. Seams reasonable and sort of covers the issue of the genny being taken away or even sold on.

 

[D Skelton]

The way I see it I can install the link at the genny and label it up accordingly. If it is ever sold then it can be removed, but the fact it is sold as a 'home or office' back up genny tells me that whereever it is used it is going to need a link in place anyway. The thing that worries me is, if that modified plug and cable gets into the wrong hands it could be lethal! People are more likely to consult an electrician if they come into possession of a genny labelled up as 'neutral earth link fitted, consult a qualified electrician before using' than if they come into possession of a seemingly normal but modified extension cable that may or may not have been labelled at some point in the past. I'm gonna have to contact the manufacturer next week regarding their warranty as I wouldn't feel comfortable doing it any other way.

 

[Marvo]

I'd be interested to hear the manufacturers reply.

 

[Engineer54]

It depends how the alternator windings are connected, sometimes it can be a pain converting a floating earth to a referenced earth. As this standby gen-set is going to be permanently located/positioned, it's no longer classed as a mobile/portable unit. As such it should be earth-neutral referenced....

 

[D Skelton]

I can't say how the windings are connected. Annoyingly the only picture I can find seems to be for a US version of the gen set:

 

[Marvo]

I can't say how the windings are connected. Annoyingly the only picture I can find seems to be for a US version of the gen set................

This just highlights the actual problem of which the manufacturers are the single largest contributer. Firstly they mis-market their products, many of them are happy to call a site generator a back-up power solution. Secondly more often than not the design of the generator makes it impossible or very difficult to install it safely. Thirdly trying to find accurate information about the windings and general wiring configuration info you're invariably on a hiding to nowhere.

I'd suggest BY LAW manufacturers should be required to do as follows;

1. A schematic of the wiring of the windings and AVR and supply points on the genny should be on a sticker that's readily visible on the genny itself.

2. Every generator sold should be clearly marked with its intended use.

3. All generators should come with a termination block to allow easy the bonding of the N + E without dismantling the panels or electrical enclosure and without voiding any warranties.

4. Every generator should be sold with an earthing kit consisting of 3 x 2.4m copper earth spikes with couplings, wiring, clamps, spade and a sledgehammer etc.

5. A complete user manual and installation manual should be available for free from the place where the generator is sold. All information therein should be in English that's free from incorrect vocabulary and sentence construction.


Failure to comply with any of the above should result in the manufacturer, the importer and the wholesaler and their immediate families being arrested and prosecuted for attempted murder

 

[rick]

Hello chaps

I understand some of this but not most of it, and it's not something I have ever been asked to do or would undertake - but I would like to understand it a bit more. Any helpful links?

Cheers

 

[D Skelton]

Hello chaps

I understand some of this but not most of it, and it's not something I have ever been asked to do or would undertake - but I would like to understand it a bit more. Any helpful links?

Cheers

Get yourself a copy of Guidance Note 5 and immese yourself in sections 411, 413, 418.3, 551 and 717 of BS 7671

 

[Knobhead]

What CR results do you get when you test the windings to the frame. I do mean CR not IR.

You’ve probably done this but I would be interested in the results.

 

[D Skelton]

What CR results do you get when you test the windings to the frame. I do mean CR not IR.

You’ve probably done this but I would be interested in the results.

Are you referring to a ductor test? If so, why would I need to carry this out? There is no connection whatsoever between winding and frame (on the piece of crap that the customer is now getting rid of).

 

[D Skelton]

Got it in writing from the manufacturer of the genny I have proposed to the customer. Fitting a link between the winding and the chassis does not invalidate the warranty