Portable Inverter Generator for home backup. What's the simplest set-up?

[Justin Time]

I know it's not neat, but can I simply run a single extension cable from a small (3KVA) petrol, portable, inverter generator, positioned outside in my yard, into my house to power a LED TV, plugged in LED lights, radio, internet hub, charge mobiles, etc, perhaps using a four-way socket system, being careful not to overload? Any precautions (RCDs? etc,) needed?

I've read plenty of posts about small portable generators and floating neutrals, transfer boxes, special CUs etc, related to setting up a more permenantly wiring system into the house's electrics- and the multiple opinions expressed - but I'm not sure that's the way we want to go in this case. Simpler is better? Or not? Indeed, a couple of my neighbours have already employed a local electrician to install a changeover switch for their gennys, but I'm wondering about competency and complications - earthing issues, etc.

The context for this question is that last year's Storm Arwen left us without electricity for 2 weeks. We live at 1500 feet above sea-level, way out in the sticks. Oil fired Aga which can be run on manual with no electricity provides cooker, kettle, toaster, drier, room warming, etc. Multi-fuel stove heats the house (no oil central heating). We can survive without the immersion heater. 3000 litres of fuel oil and several tons of anthracite saved us last year (I know, I know, not very green, but we were comfortable while some locals with air-sourced pumps and electric depending central heating systems were stuffed).

Our overhead Northern Power Grid main supply is always, weekly, cutting out since January 2022, albeit from just a few seconds to 15 mins or so, especially since they 'fixed' the 19 snapped overhead poles in December 2021. They seemingly ingore our complaints. These small outages do not bode well for the coming winter! The genny isn't needed for survival, but would make life a bit easier and save a fortune on candles and small batteries!

Any advice much appreciated before I purchase a genny.

 

[Lucien Nunes]

A freestanding generator with a floating (a.k.a. IT, electrically separated, neutral not earthed) output is safe when powering one item of equipment. Once you start spreading its output to multiple appliances, the floating output starts to hamper attempts to protect against electric shock. With small items that are mainly class II (e.g. phone chargers, TV etc) the risk is minimal and one might argue that it's trivial compared to other risks in the circumstances and just crack on. But it's worth understanding the cause.

If one appliance has a fault or insulation defect to earth from either of the two live conductors, it will go undetected as it won't create any leakage current on a floating system. However it creates a hidden risk of shock from the other conductor to earth, as that would complete the a path from one live conductor through the person being shocked to earth, then from earth back through the undetected first fault to the other live conductor. An overall RCD at the generator will not detect this occurrence as both the first fault and the shock path are downstream of it and therefore do not cause an imbalance for it to detect. It would detect and disconnect the same shock on a conventional TN supply because although shock would occur downstream of it, the current would return to the circuit at the N-E link upstream, creating an imbalance at the RCD.

Therefore fitting an overall RCD to a floating generator would give a false sense of safety when it is unable to function. Protection can be achieved by supplying appliances via individual RCDs e.g. in RCD sockets. In that case, if one appliance gets faulted to earth and a shock path is created at another, both RCDs see an imbalance. But by the time one has gone to this bother, one might have linked N to E and to a rod and had a TN system.

 

[Justin Time]

Many thanks Lucien for your speedy reply and explanation. I'm pushing the boundaries of my 1970s "O'-Level Physics knowledge in comprehending what you've helpfully explained, but I think I get the gist. In short, ONE piece of equipment (say the TV) connected to the extension cable from the genny is OK, but TWO OR MORE items opens up some risks that need to be understood.

I have read elsewhere that in most generators' windings, a link of N to E can be made (presumedly this isn't normally set up in most generators, but is achieved post purchase, by an electrician?), but I've also read that grounding the genny, say via the labelled E point on the front of the control panel via a wire to an iron stake, runs some risks too and that earth rods need to be tested for functionality by someone who knows what they're doing (I don't!), rather than just hooked up to a metal fence, rod hammered into the lawn, or similar.

Would using indivudal RCD plugs (e.g screwfix RCD plug), on the extention cable's multiple (say 4) sockets, for each of four peices of equipment, serve any purpose, or is that also just providing a false sense of security?

 

[plugsandsparks]

A possible alternative, one that i have used myself for exactly the issues you describe. I too used to have a small petrol generator and have used it occasionally but found it noisy and always running out of juice.
I have a 1000W inverter built into my car, i use it for long sessions on the laptop and charging batteries when i am out in the field. When power is interrupted at home i have run an extension from the back of the car to the house like you describe. The items you describe take very little power but anything adventurous like the fridge/freezer are doomed.

Hope this helps

P&S

 

[James]

most of the light duty appliances you are listing are likely to be double insulated class 2 appliances and therefore do not have an earth.

if it was for my own use, i would just get on with it, drop a 4 way extension lead through the window, plug in a lamp, tv and internet box and be done with it.

@plugsandsparks idea above is good, it has exactly the same electrical risks involved as a small generator but is of course silent so much better overnight.

 

[Lucien Nunes]

I agree that with mainly class II appliances the shock risk is tiny and can generally be ignored. I wanted to explain why this can only be pushed so far. If I wanted to run a bunch of class II items all inside the equipotential zone I'd plug and go, if it started to include the washing machine and central heating system I'd TN it.

 

[Justin Time]

WOW! I've never heard of a built in inverter for a car. You can guess what I'm going to be 'googling next. Thanks too James.

 

[James]

thank god for that,
its not often that I drop in a piece of information that on the face of it may seem to disagree with @Lucien Nunes , especially when we have been treated to an in depth education as to why it might be a bad idea.
can take you back to worrying about putting your hand up in class, just in case your answer was wrong!!!

and just to add, i did once put a plug on my central heating boiler when we had a power cut in the depths of winter, plugged in generator on extension lead and discovered the heating would not fire up, it ignited and ran for 5 seconds and shut down with a fault.
I learnt all about single wire flame detectors that weekend and the fact that small portable generators have no ground reference for the Neutral

 

[plugsandsparks]

https://www.NoLinkingToThis/p/maypole-mp56100-2-1a-1000w-power-inverter-with-usb-12v/113fy

If you want a deluxe version which has a better waveform

1000W 12V to 230V/240V Pure Sine Wave Inverter With English Standard Socket (with UPS Function)

Whether for a van or a cabin, the Renogy 1000W Pure Sine Wave Power Inverter acts as a DC to AC converter that allows you to power your household appliances.

uk.renogy.com

The cheaper version is OK for phone chargers, router PSUs etc but if you are unsure and have anything with a magnetic component like transformer, motor or a very expensive TV , lol i would go deluxe.

Also if you do run all your electronic equipment overnight, you may find a flat battery in the morning... eek

 

[Justin Time]

https://www.NoLinkingToThis/p/maypole-mp56100-2-1a-1000w-power-inverter-with-usb-12v/113fy

If you want a deluxe version which has a better waveform

1000W 12V to 230V/240V Pure Sine Wave Inverter With English Standard Socket (with UPS Function)

Whether for a van or a cabin, the Renogy 1000W Pure Sine Wave Power Inverter acts as a DC to AC converter that allows you to power your household appliances.

uk.renogy.com

The cheaper version is OK for phone chargers, router PSUs etc but if you are unsure and have anything with a magnetic component like transformer, motor or a very expensive TV , lol i would go deluxe.

Also if you do run all your electronic equipment overnight, you may find a flat battery in the morning... eek

I'm fascinated by these devices, I'd never encountered. Ain't modern technology great. So many thanks for the links.

I'm thinking big! And found this - 2500W! Machine Mart Comparatively, lots of £s though, albeit a similar cost to some of the smaller, Chinese engined, petrol generators. It's a shame I sold my old diesel engined motor and now run a petrol Subaru which, reportedly, do suffer from some battery issues. Still....it's an option.

I'm also lucky that I don't have any close neighbours so a petrol generator's noise won't be an issue. Thinking about it though, the car inverter option means I wouldn't need to contruct a genny shed/cover so I could run it in foul weather, exactly when it's most likely to be needed.

 

[plugsandsparks]

https://www.stephill-generators.co.uk/contentfiles/SG-156.pdf

If you are wanting power, then batteries dont cut it, but this will. Get your electrician to wire it in so you can wheel this out when you need it and plug it in to a purpose made plug. If you have all LED lighting , this will get you through the night watching back to back episodes of Breaking Bad.
Seriously though a hard wired solution with this type of genny is probably what i would do if i suffered poor grid power relaibility

 

[James]

Hyundai DHY8000SELR-T Multi-Phase Diesel Generator - Generators Direct

*Please be advised that Hyundai Power Products now have an extended lead time and you may not receive them next day. The current delivery time is estimated at 1-3 working days.* *for single phase kVA is based on an assumed load factor of 0.8. The DHY8000SELR-T is a compact yet powerful long run...

www.generators-direct.co.uk

that's what i have at home, advantages are it only needs filling up every 24h of running, to be honest i think it will last about 35hrs per fill up based on previous usage.
fuel use is normally less than 1L per hour

 

[Justin Time]

https://www.stephill-generators.co.uk/contentfiles/SG-156.pdf

If you are wanting power, then batteries dont cut it, but this will. Get your electrician to wire it in so you can wheel this out when you need it and plug it in to a purpose made plug. If you have all LED lighting , this will get you through the night watching back to back episodes of Breaking Bad.
Seriously though a hard wired solution with this type of genny is probably what i would do if i suffered poor grid power relaibility

Many thanks again `P&S for that info. My concern is finding a competent electrician locally who is experienced enough to wire one into the house system given some of the complications mentioned. That's why I'm considering a simpler system - just one extension cable from the genny, through the 'cat-flap' sort of method, to power a small number of low wattage items.

 

[Justin Time]

Hyundai DHY8000SELR-T Multi-Phase Diesel Generator - Generators Direct

*Please be advised that Hyundai Power Products now have an extended lead time and you may not receive them next day. The current delivery time is estimated at 1-3 working days.* *for single phase kVA is based on an assumed load factor of 0.8. The DHY8000SELR-T is a compact yet powerful long run...

www.generators-direct.co.uk

that's what i have at home, advantages are it only needs filling up every 24h of running, to be honest i think it will last about 35hrs per fill up based on previous usage.
fuel use is normally less than 1L per hour

Like it ! That's some serious ummmph I'm thinking more inline with something much smaller like a Honda eu2200is or perhaps a eu3200is which can apparently be paralleled up if need be. That way, I can sling it in the back of the car if required. I have also looked at Champion generators, which are dual fuel (e.g. Champion ) with all those advantages that come with LPG vs petrol. Considerably cheaper than Honda and more power per £, although I've had some very positive experiences with small Honda engines over the years and the 5 year warranty includes parts and labour, plus there are plenty of local dealerships.

 

[terry298657]

which has a better waveform,1000w or 2000w inverter, just confused