Generator transfer switch

[flying haggis]

I have read earlier that this is unsafe and have seen this called a "suicide cable". Could someone explain why it is dangerous? (Just out of curiosity; I am not thinking of doing this).

they are also called "widow makers" for the same reason. they are a dangerous and stupid idea

 

[flying haggis]

And when the power comes back on the grid is then feeding back in to the generator! And the "grid" has bigger generators than you....................

 

[Spectric]

An even bigger issue would be that the generator and grid would not be in phase.

 

[TomTheToolMan]

Landlines should always work
with a hardwired phone
cordless phones need power
you should always have one hardwired phone plugged in

Unfortunately bt are rolling out IP phones. A consequence of this is hardwired phones are becoming obsolete.

 

[Tuco]

If you are going whole house, then you need a large two pole changeover switch rated 60, 80, 100 Amps because it's going in your meter tails and will have to carry the full load of the house when switched to mains not Genny. You can't do this yourself. You'll have to get a sparky to do it for you.

Kraus & Naimer make suitable switches. They are big and will probably set you back a good part of £100 plus the installation.

If I were doing it, I'd have the sparky modify my wiring so that a smaller transfer switch came AFTER my consumer unit. This would then need to feed probably 3 miniature circuit breakers ( the house wiring has to be protected correctly even when fed from the genny). I'd run only 1 lighting circuit, the gas boiler circuit, the freezer and a double socket for the tv/computer + router. You can't be doing without UKW during a powercut
A small genny should be enough for that and you won't be able to mess up by trying to boil a kettle with it.
The second method is unlikely to be cheaper but it's a better solution.

This isn't a DIY job. It's notifiable to building control.

Tell your friend he's stupid and a scumbag for putting his wife and kids lives at risk, and potentially some poor sod doing maintenance on the supply cables. It's worse because he realises it's dangerous and is doing it anyway.

Thank you for this very detailed answer, just what I was after

 

[Yojevol]

I know its very unsafe but a friend keeps a double ended plug on a cable which he has used in the past (plugged into the cooker socket). But he’s always worried his kids will find it when it’s not in use and start messing around with it even though he always tries to hide it in a safe place when he’s not using it.

This is all about risk assessment. I've used the double plug cable method once in the past; in the 1987 big storm when our lines were down for a week. I rigged it up for my elderly neighbours who were in a desperate situation.
To mitigate against any risk of interference, the connection was made in a locked garage with the genny outside. To avoid any possible mismatch should the grid come back, on the main switch on the consumer unit (also in the garage) was turned off.
Your friend has assessed the risks and has taken steps to minimise them to a level which is acceptable to him and his family.
It seems likely that we're going to suffer regular power cuts for years to come, so safe permanent installations may become attractive and affordable.
Brian

 

[HamsterJam]

Sort of related question- if there are domestic solar panels feeding into the grid, how do they avoid feedback into the grid in a power outage?

There must be protection in the invertors otherwise with a power outage the invertor would see effectively a short circuit, you would be expecting it to feed the grid.

Spectric is correct. It is a requirement of connecting to the grid that an inverter needs mains to be present for it to start generating. I.e. No mains, no solar power.
If someone is working on the network, the last thing they need is solar installations feeding back into the system keeping it live and I know for sure if the power failed, there is no way my solar installation could support the entire street which is what would happen.

 

[HamsterJam]

The bigger problems today are that many gas hobs will not function without electricity due to the flameout protection, the same for gas boilers and landlines are also not going to work but then many have some form of mobile.

We don’t have gas in the village so use oil for cooking and heating/hot water plus we have solar PV. All of these stop if the power goes off.
Fortunately we have a log burner so at least we won’t freeze.
Might be glad I kept my old Coleman petrol camp stove. Also thinking about buying a gas barbecue.

Landlines should be on some sort of UPS or generator. Mobile base stations usually have UPS to cover a short period but generally not generators.

 

[Limey Lurker]

When I was involved with these type of backup systems we used to have a large UPS to hold the supply up whilst the generator came on line.


unless the local exchange is also having a power outage.

Do they no longer have battery back-up?

 

[nickds1]

Unfortunately bt are rolling out IP phones. A consequence of this is hardwired phones are becoming obsolete.

Not quite as simple as that. If you have BT Residential FTTP then they insist you switch your POTS (analogue) phone to their Digital Voice service which in turn means that you HAVE to have a BT SmartHub (as that's the only device that supports this). For 97% of BT Residential installations this is fine, but e.g. in our case, I have to use a different router (everything is Ubiquiti UniFi). BT Residential cannot unbundle FTTP & Digital Voice, which is a show-stopper for us, however... BT Business can. What's more, with BT Business I get 30MBs up and 120MBs down for less money that I was paying for the BT Residential service (10MBs up and 50MBs down), and I get to keep my analogue phone plus I don't need the BT SmartHub. On average I'm getting the full 30MBs up and about 110MBs down).

So, it's worth remembering that the 4 bits of BT that we deal with (Residential, Business, EE & OpenReach) are, but equally are not, the same company and the first three offer competing services.

(*) We also have an EE 4G Cellular Modem which gives us about 20MBs up and the same down where we are - this is our internet backup connection.

 

[Spectric]

All I want is full fibre to my house, but not happening anytime soon as the area is too rural. The system uses a fibre from the exchange to a local box where a passive splitter divides it to several properties, each fibre carries so many channels and so no power needed.

 

[nickds1]

All I want is full fibre to my house, but not happening anytime soon as the area is too rural. The system uses a fibre from the exchange to a local box where a passive splitter divides it to several properties, each fibre carries so many channels and so no power needed.

It's OT for this thread... but FTTP needs permanent power for the ONT - the Optical Network Termination box in your house - this is the box that converts the fiber optic signal to an ethernet RJ45 port. Without power to the ONT on your wall, you have no broadband so that may need to be on a UPS together with your router etc.

 

[Dabop]

Re solar not working when the grid is down- there are inverters that can run while the power is off- these are called 'hybrids' and they do cost more than simple gridtie inverters...

Depending on how much you want to spend, the cheapest hybrids (cost about twice as much as a standard gridtie one) simply run at reduced power from solar only- no batteries- so these will usually deliver about 1/5th of the panels rated output, and only during solar generating hours ie they can be handy when there is extended periods of outages such as cyclone damaged grids here in Australia, which could take a week or more to be repaired- a 'solar only' hybrid allows you to recharge 'camping lights' phones, tablets and laptops, or even a small battery to run a camping 12v inverter offand keep your fridge running during the day (turn it up to full, and fill the fridge and freezers unused areas with plastic bottles 3/4 filled with water- these will keep it cool at night even with no power) - these often only have a single socket on the front panel to plug stuff into...
(Outback makes inverters that can do this- a well known company that makes both gridties, hybrids and offgrid inverters, another is well known one is Growatt (note that not ALL their range does this, just selected ones, in both cases)

Next you have hybrids with a attached battery pack- often 24v or 48v- these require a sparky to isolate the circuits you want power to, these are then put on a separate sub-board- depending on the inverter, it may incorporate automatic switching, or have a manual 'changeover' switch needed (mine is such an inverter, although I use it purely as offgrid only) obviously more expensive than a straight gridtie only one (in my case about four times the price but as I am offgrid entirely, a straight gridtie would be pretty useless lol)

Mines a 230v, pure sinewave, 12kw continuous, 36kw for 20 seconds peak, dual MPPT solar inputs rated at 3kw each, circuits connected to the output have auto switching, and can be used as 'changeover' or in UPS mode, where they run continuously off the inverter, and it runs off the mains (good for places with 'dirty power') by Sigineer

Another option that is popular here in Australia is the 'powerwall' type system- may here have it to reduce electricity costs by storing power generated during the day from their solar in the powerwall first, then exporting any excess like a normal gridtie, during the night the powerwall supplies your household needs, only if the battery is close to depleted or the power required is more than its internal inverter can supply, will it go back to the mains grid- sorta like being 'offgrid' but using the grid as the 'emergency backup' instead of a petrol powered genny...- these run in the hundreds of volts range, Tesla is the one that 'everyone talks about', but there are many others Panasonic, BYD BBox etc that have been around just as long if not longer, and are far better value for money than the Tesla offerings...

https://www.savingwithsolar.com.au/byd-b-box-australia-review-price/(not affiliated in any way with any of them, I'm just a mostly retired sparky who has been doing solar for the last forty years lol)

 

[Sideways]

This is all about risk assessment. I've used the double plug cable method once in the past; in the 1987 big storm when our lines were down for a week. I rigged it up for my elderly neighbours who were in a desperate situation.
To mitigate against any risk of interference, the connection was made in a locked garage with the genny outside. To avoid any possible mismatch should the grid come back, on the main switch on the consumer unit (also in the garage) was turned off.
Your friend has assessed the risks and has taken steps to minimise them to a level which is acceptable to him and his family.
It seems likely that we're going to suffer regular power cuts for years to come, so safe permanent installations may become attractive and affordable.
Brian

It would have been safer to simply install a lockable 3 pole isolator switch in a suitable circuit and hard wire the genny in. It would still have been non compliant / illegal because there are no interlocks to prevent the switches being set wrongly, but at least you wouldn't have had the suicide cable hazard.

 

[MikeK]

Here is a thread from March 2022 with a similar discussion.

https://www.ukworkshop.co.uk/threads/advice-on-buying-an-emergency-generator.136261/

 

[clogs]

For the last 20 odd years have lived with powercuts sometimes as long as a week.....
we found it quite conv to run a cable from the genny to supply the fridges / freezers
plus the odd light and the comp.....then when the power comes back on just replug all the stuff back into the mains again...
we cook on gas...
for the odd power cut I have a 2000watt Honda and for the longer jobs a Lister Diesel.......
If I was to build a new house it would be off grid and have a seperate system for the genny and or plus a change over switch....but to modify the excisting system would be to expensive....
besides I'm retired, what ever that is and have a little extra time...

 

[Spectric]

we found it quite conv to run a cable from the genny to supply the fridges / freezers

plugging items like freezers into a lead powered by a generator is ok so long as the lead is suitably rated and the generator can handle the load. It is the people who want to power the entire house and often the neighbours as well that cause the safety concerns and for them ignorance is bliss.

 

[Yojevol]

It would have been safer to simply install a lockable 3 pole isolator switch in a suitable circuit and hard wire the genny in. It would still have been non compliant / illegal because there are no interlocks to prevent the switches being set wrongly, but at least you wouldn't have had the suicide cable hazard.

Agreed, but like Met Office, we didn't foresee the 1987 big storm

 

[flying haggis]

and the scientists say they can tell us what the climate will be like in a hundred years time but cant tell us what the weather will be like next week...

 

[Tuco]

Re solar not working when the grid is down- there are inverters that can run while the power is off- these are called 'hybrids' and they do cost more than simple gridtie inverters...

Depending on how much you want to spend, the cheapest hybrids (cost about twice as much as a standard gridtie one) simply run at reduced power from solar only- no batteries- so these will usually deliver about 1/5th of the panels rated output, and only during solar generating hours ie they can be handy when there is extended periods of outages such as cyclone damaged grids here in Australia, which could take a week or more to be repaired- a 'solar only' hybrid allows you to recharge 'camping lights' phones, tablets and laptops, or even a small battery to run a camping 12v inverter offand keep your fridge running during the day (turn it up to full, and fill the fridge and freezers unused areas with plastic bottles 3/4 filled with water- these will keep it cool at night even with no power) - these often only have a single socket on the front panel to plug stuff into...
(Outback makes inverters that can do this- a well known company that makes both gridties, hybrids and offgrid inverters, another is well known one is Growatt (note that not ALL their range does this, just selected ones, in both cases)

Next you have hybrids with a attached battery pack- often 24v or 48v- these require a sparky to isolate the circuits you want power to, these are then put on a separate sub-board- depending on the inverter, it may incorporate automatic switching, or have a manual 'changeover' switch needed (mine is such an inverter, although I use it purely as offgrid only) obviously more expensive than a straight gridtie only one (in my case about four times the price but as I am offgrid entirely, a straight gridtie would be pretty useless lol)

Mines a 230v, pure sinewave, 12kw continuous, 36kw for 20 seconds peak, dual MPPT solar inputs rated at 3kw each, circuits connected to the output have auto switching, and can be used as 'changeover' or in UPS mode, where they run continuously off the inverter, and it runs off the mains (good for places with 'dirty power') by Sigineer

View attachment 145036

Another option that is popular here in Australia is the 'powerwall' type system- may here have it to reduce electricity costs by storing power generated during the day from their solar in the powerwall first, then exporting any excess like a normal gridtie, during the night the powerwall supplies your household needs, only if the battery is close to depleted or the power required is more than its internal inverter can supply, will it go back to the mains grid- sorta like being 'offgrid' but using the grid as the 'emergency backup' instead of a petrol powered genny...- these run in the hundreds of volts range, Tesla is the one that 'everyone talks about', but there are many others Panasonic, BYD BBox etc that have been around just as long if not longer, and are far better value for money than the Tesla offerings...

https://www.savingwithsolar.com.au/byd-b-box-australia-review-price/(not affiliated in any way with any of them, I'm just a mostly retired sparky who has been doing solar for the last forty years lol)

Thank you, this is all very helpful stuff and v interesting to see how it’s done across the world.