Illegal mains plug?.....possibly lethal

[bradfordbuffer]

7 hours ago, roythebus said:

Ring mains and radial systems both seem to work perfectly well here and abroad from what I've seen in Europe. The British fetish to earth everything and PAT test everything amuses those on the continent.

 

I used to own a Wurlitzer jukebox that kept blowing fuses when i bought it. It turned out that the previous owner had a problem with it blowing fuses because I discovered the change-over relay that made something inside go the other way and flipped its contacts so they had jammed. He replaced the slow blow fuse with a no-blow fuse, (see above) with a nail which then blew not only the 13A in the plug but the house RCD as well!

 

In my old workshop we had a set of Prolift vehicle lifts, 3 phase 5 tonne jobbies. We had a problem with those, so someone decided to try to get them to work by holding in a relay. that was the one that reversed the phases to reverse the lift motors. Not only did that blow the internal fuses but the 63A fuses in the 3-phase input! It was quite a spectacular BANG!

 

My previous house was built by Colt, a novel timber frame design from the late 1920s, but built in 1971. I was installing some double sockets and found several loose connections in the backs of the old single sockets. I've learnt that these can work loose just with the 50hz frequency as the cause.

No blow fuse!...is that the same fuse used in 1st gen dmus brake van signal buzzer circuit 1 ½inch nail rapped in tin foil until it remained in place without been rattled out....is it the old saying its not the voltage that kills you it's the amps!...still stayed clear of 25.000v in 34 years on railway...if it buzzes in the rain its dangerous! ☠

[Nearholmer]

6 hours ago, AndyID said:

Admittedly It is pretty unlikely (and probably not even allowed) but it is possible to exceed the cable rating without any wiring fault. e.g. if the ring was 21 meters long and someone was clever enough to pull 30A from it 1 meter from the feed point there would be 28.6A flowing through the 1 meter length of cable. The other 20 meters would only be passing 1.4A

 

I haven’t checked the figures, but they sound right by instinct to me.

 

But, U.K. design practice and regulations would not allow a single 30A point load on a typical domestic ring main, we used radials for large point loads such as cookers.

 

So, I would respectfully suggest that it is both true and slightly misleading.

 

You could possibly have two 13A loads on a pair of sockets close-up to the start of the ring, but there are very few forms of continuous 13A loads that are used in a domestic setting - most loads of that magnitude in a home are intermittent ones.

 

The plain fact is that the U.K. practice and standards have worked very well and safely for many years. Where things will probably get interesting soon is in the transition from wide use of gas heating, to wide use of electrical heating in homes.

[Michael Hodgson]

3 hours ago, Nearholmer said:

 

 

The plain fact is that the U.K. practice and standards have worked very well and safely for many years. Where things will probably get interesting soon is in the transition from wide use of gas heating, to wide use of electrical heating in homes.

 

All very well for new housing, but I don't see it happening quickly for existing buildings unless there are massive financial incentives & do it for free for those in social housing.  My parents had night storage heating for 30 years, until eventually mains gas reached the village, by which time most of the street had already ripped out their clapped out heaters and installed coke, oil or bottled gas, then needed to redecorate the whole house.  The electric heating was unreliable anyway because every time you really needed the heating, the supply cables would be blown down in a storm. 

 

So what sort of installation would be likely ?  Will everybody go back to night storage, will it be underfloor heating, will the politicians change the rules and force everybody to have active smart meters limiting load during peak hours?  Rip out pipes and radiators, floorboards up, new wires all round the house?  I suppose it would help solve the post-covid unemployment problem to retrain many thousands to work as domestic installation engineers and another lot as decorators to sort out the mess the first lot make.

Edited December 9, 2020 by Michael Hodgson

[Nearholmer]

It is a conundrum, isn't it?

 

One option, although I'm not sure how thermally efficient it could be made*, surely has to be to swap out gas boilers for electric boilers, and retain water as the medium for final transport of energy in "legacy houses". But, even that poses questions about the capacity of street mains and domestic connections if no energy store is provided at the house, given that gas boilers typically have ratings higher than the rating of the typical domestic electrical connection.

 

Add this one to questions about capacity and points of connection for electric vehicle charging and it gets even more interesting, and to me it does tend to point in the direction of domestic energy storage, to remove large peaks from demand, whether that be by storing energy in batteries (including, of course, using the car battery to support domestic demand), or in warm bricks (storage heater technology), or by some other means.

 

Insulate your house and buy thermal undies!

 

*The answer to that seems to be "compared with what?". An electric boiler will be more thermally efficient than even the best gas boiler, because there are no losses via a flue. But, how an electrically heated water-medium system compares in efficiency with direct electric heaters I'm still not sure - it must be lower efficiency, but my gut feel is not hugely.

Edited December 9, 2020 by Nearholmer

[Crosland]

1 hour ago, Michael Hodgson said:

Rip out pipes and radiators, floorboards up, new wires all round the house? 

Why? When you can install an electric boiler?

[Michael Hodgson]

51 minutes ago, Crosland said:

Why? When you can install an electric boiler?

Oh yeah, I've still got an electric immersion heater that I've not used in years.  I thinks it's on a radial circuit with its own 15A fuse.  I suppose they could put an electric boiler in the airing cupboard.

[Grovenor]

From what I've seen the conversion from gas is supposed to be to heat pumps, either air source or ground source.

[Steven B]

Leave the old piping in place and hand electric heaters in place of the water filled radiators.

 

There are other options for providing heat and hot water. District heating systems turn energy from burning household waste into a mains hot water system. Homes and businesses where heat-exchangers allow its use around the building. Such systems exist in Manchester, Glasgow, Leeds, London, Nottingham and Sheffield.

 

Steven B.

[Edwin_m]

5 hours ago, Nearholmer said:

It is a conundrum, isn't it?

 

One option, although I'm not sure how thermally efficient it could be made*, surely has to be to swap out gas boilers for electric boilers, and retain water as the medium for final transport of energy in "legacy houses". But, even that poses questions about the capacity of street mains and domestic connections if no energy store is provided at the house, given that gas boilers typically have ratings higher than the rating of the typical domestic electrical connection.

 

Add this one to questions about capacity and points of connection for electric vehicle charging and it gets even more interesting, and to me it does tend to point in the direction of domestic energy storage, to remove large peaks from demand, whether that be by storing energy in batteries (including, of course, using the car battery to support domestic demand), or in warm bricks (storage heater technology), or by some other means.

 

Insulate your house and buy thermal undies!

 

*The answer to that seems to be "compared with what?". An electric boiler will be more thermally efficient than even the best gas boiler, because there are no losses via a flue. But, how an electrically heated water-medium system compares in efficiency with direct electric heaters I'm still not sure - it must be lower efficiency, but my gut feel is not hugely.

 

2 hours ago, Grovenor said:

From what I've seen the conversion from gas is supposed to be to heat pumps, either air source or ground source.

Apparently an air source heat pump can be used to run radiators, but can only heat water to around 45 degrees.  This possibly makes it more thermally efficient than a gas boiler, because the lesser temperature difference between the pipes and their surroundings means less heat is lost in places it isn't needed.  But it also means most radiators will need replacing with larger ones.  

 

A heat pump is arguably more than 100% efficient, because the amount of useful heat out is (hopefully) more than the amount of electrical energy needed to power it.  

[APOLLO]

My energy tariffs

 

Cost of Gas per KW hour  2.583 Pence

Cost of Electricity per KW hour  15.798 Pence

 

My new condensing gas boiler is 90-95% efficient. An electric powered replacement would cost a hell of a lot more to run, even at 100% efficiency.

 

Ban gas, petrol, diesel, meat, dairy, flying you name it ------------ I'll just laugh & shake of head !!!!!!!!!!!!!!!!!

 

Brit15

 

 

 

 

[APOLLO]

2 minutes ago, Edwin_m said:

 

Apparently an air source heat pump can be used to run radiators, but can only heat water to around 45 degrees.  This possibly makes it more thermally efficient than a gas boiler, because the lesser temperature difference between the pipes and their surroundings means less heat is lost in places it isn't needed.  But it also means most radiators will need replacing with larger ones.  

 

A heat pump is arguably more than 100% efficient, because the amount of useful heat out is (hopefully) more than the amount of electrical energy needed to power it.  

 

Interesting. On a cold day I'll set my gas C/H boiler at 45 deg C and see how I go on with my existing system. Best do it when the Mrs is out shopping !!

 

Brit15

 

 

[Nearholmer]

1 minute ago, APOLLO said:

My new condensing gas boiler is 90-95% efficient. An electric powered replacement would cost a hell of a lot more to run, even at 100% efficiency.

 

Certainly would on present tariffs, which is why barely anyone uses them.

 

Massive bust-up coming about this whole question of the near-term cost of moving away from fossil fuels and who will bear it. Its a political hot potato.

[Tankerman]

16 hours ago, bradfordbuffer said:

No blow fuse!...is that the same fuse used in 1st gen dmus brake van signal buzzer circuit 1 ½inch nail rapped in tin foil until it remained in place without been rattled out....is it the old saying its not the voltage that kills you it's the amps!...still stayed clear of 25.000v in 34 years on railway...if it buzzes in the rain its dangerous! ☠

 

The saying I was taught, both by electricians in Falmouth Docks and lecturers at Cornwall Tech College was "It's the volts that jolts, but it's the mils (for milliamps) that kills." The TV's of the 1950's/early '60's had a cathode tube voltage  somewhere between 15,000 to 25,000 volts, but a very low current drain. I've been told by those who experienced them that a shock from one would knock you sideways but weren't lethal. 

[Nigelcliffe]

1 hour ago, APOLLO said:

My energy tariffs

 

Cost of Gas per KW hour  2.583 Pence

Cost of Electricity per KW hour  15.798 Pence

 

My new condensing gas boiler is 90-95% efficient. An electric powered replacement would cost a hell of a lot more to run, even at 100% efficiency.

 

Ban gas, petrol, diesel, meat, dairy, flying you name it ------------ I'll just laugh & shake of head !!!!!!!!!!!!!!!!!

 

Brit15

 

 

A heat pump is around 350%.  ( The energy comes from the air outside the house, or the ground, the electricity is used to extract that heat - hence term heat-pump).  

 

With your current electric/gas tariffs it doesn't cost in, but the comparison would be nearer to Gas=2.6p, Elec=4.5p.   Not that big a gap to close. 

 

 

- Nigel

 

[giz]

Would they be the heat pumps that a housing association that Mrs Giz used to work for had to remove and replace with gas boilers on a whole estate of new houses after the residents went ballistic after receiving electricity bills of £1000s. It even ended up on the local BBC news. All the heat pumps ended up being stored in their warehouse.

[Michael Hodgson]

2 hours ago, Nearholmer said:

Massive bust-up coming about this whole question of the near-term cost of moving away from fossil fuels and who will bear it. Its a political hot potato.

 

I used an electric microwave to cook spuds just now - should I be using a blowlamp?

[APOLLO]

1 hour ago, Nigelcliffe said:

 

A heat pump is around 350%.  ( The energy comes from the air outside the house, or the ground, the electricity is used to extract that heat - hence term heat-pump).  

 

With your current electric/gas tariffs it doesn't cost in, but the comparison would be nearer to Gas=2.6p, Elec=4.5p.   Not that big a gap to close. 

 

 

- Nigel

 

 

I was referring to an electric replacement boiler to my existing gas boiler which would be economically unfeasible.

 

Heat pumps I know nothing about, except they are expensive to install, not all houses are suitable, and their performance (against conventional gas boilers) is questionable.

 

We will see what happens politically !!

 

Brit15

[AndyID]

13 hours ago, Nearholmer said:

 

I haven’t checked the figures, but they sound right by instinct to me.

 

But, U.K. design practice and regulations would not allow a single 30A point load on a typical domestic ring main, we used radials for large point loads such as cookers.

 

So, I would respectfully suggest that it is both true and slightly misleading.

 

You could possibly have two 13A loads on a pair of sockets close-up to the start of the ring, but there are very few forms of continuous 13A loads that are used in a domestic setting - most loads of that magnitude in a home are intermittent ones.

 

The plain fact is that the U.K. practice and standards have worked very well and safely for many years. Where things will probably get interesting soon is in the transition from wide use of gas heating, to wide use of electrical heating in homes.

 

The plain fact is it's not at all misleading and the regulations do allow it.

All it takes is a spur which is perfectly legal and very common.

 

The resistance of the cable is proportional to its length and current is inversely proportional to resistance so for the 1 meter cable the current is

30 x 20/21 = 28.57A.

For the 20 meter cable it's

30 x 1/21 = 1.43A

 

[Damo666]

3 hours ago, giz said:

Would they be the heat pumps that a housing association that Mrs Giz used to work for had to remove and replace with gas boilers on a whole estate of new houses after the residents went ballistic after receiving electricity bills of £1000s. It even ended up on the local BBC news. All the heat pumps ended up being stored in their warehouse.

 

 

Wow, and interesting.

I'd be interested in knowing why the scheme failed? Was it that the houses weren't insulated sufficiently, was it that the client just wanted to 'Greenwash' the scheme but didn't really buy-into an ecological scheme, or did one/several of the consultants c*ck it up? Or something else?

[RJS1977]

11 hours ago, Nearholmer said:

 

 

*The answer to that seems to be "compared with what?". An electric boiler will be more thermally efficient than even the best gas boiler, because there are no losses via a flue. 

 

But that's only looking at the efficiency of the boiler itself. If the energy to run the boiler comes from a gas-fired power station, there will be thermal losses at the power station, transmission losses in the National Grid and more losses in the boiler.

 

Using a thermal power station to generate electricity to power an electric heat source is a very inefficient way of doing things. 

[AndyID]

7 hours ago, Tankerman said:

 

The saying I was taught, both by electricians in Falmouth Docks and lecturers at Cornwall Tech College was "It's the volts that jolts, but it's the mils (for milliamps) that kills." The TV's of the 1950's/early '60's had a cathode tube voltage  somewhere between 15,000 to 25,000 volts, but a very low current drain. I've been told by those who experienced them that a shock from one would knock you sideways but weren't lethal. 

 

It's really the Joules as does ye in - which is to say it's the amount of energy you receive. It's a combination of current and time. A very short duration current pulse cannot deliver a lot of energy which is why the static discharge spark you generate after you charge yourself up by walking on a nylon carpet can be extremely painful but is not typically lethal.

 

If your shoes are good insulators you can easily charge your body surface to many thousands of volts but your body doesn't have enough surface area to store a lot of charge (energy) although it is quite enough energy to kill a lot of semi-conductor devices.

 

Another interesting factoid that I only discovered recently. If you are swimming and you get an electric shock it's much better to be in salt water than fresh water. In salt water the water is the conductor. In fresh water you are the conductor.

[Nearholmer]

8 hours ago, RJS1977 said:

Using a thermal power station to generate electricity to power an electric heat source is a very inefficient way of doing things

The question always has to be: compared with what?

 

I’ve never studied the source to warm sitting room efficiency chain for gas or for heat-pumps, or a coal fire, or a paraffin heater, or..... or nuclear-electric come to that.

[LimboBrit]

14 hours ago, Tankerman said:

 

The TV's of the 1950's/early '60's had a cathode tube voltage  somewhere between 15,000 to 25,000 volts, but a very low current drain.

A good static grass applicator will produce a voltage around this level. Luckily the output currents are limited.

[giz]

9 hours ago, Damo666 said:

 

 

Wow, and interesting.

I'd be interested in knowing why the scheme failed? Was it that the houses weren't insulated sufficiently, was it that the client just wanted to 'Greenwash' the scheme but didn't really buy-into an ecological scheme, or did one/several of the consultants c*ck it up? Or something else?

I don't think much was made public for legal reasons. I found this on the internet but it dates from before the systems were removed:

https://www.insidehousing.co.uk/news/news/another-landlord-hit-by-heat-pump-problems-35637

 

[Guy Rixon]

13 hours ago, Nigelcliffe said:

 

A heat pump is around 350%.  ( The energy comes from the air outside the house, or the ground, the electricity is used to extract that heat - hence term heat-pump).  

 

Possibly not in the winter? When We had an air-source heat pump installed, the year-round average efficiency was reckoned around 200% or a little less; OK, but not spectacular. The heat pumps are very good at heating water for your shower in summer and not so good at heating your house in winter.