Generators....

[JohnW2]

I'm told the most economical way to boil water for a mug of tea is to put it in the microwave.

If that's true, it would rather surprise me, given that a kettle (with only one mug of water in it!) seems like a much more direct/simple way of converting electricity into heat, without any other significant (electrical) losses.

Kind Regards, John

 

[JohnD]

not heating the element

not heating the kettle

only heating the exact amount of water that fills the mug

try timing it.

 

[AdrianUK]

Having done a fair bit of temporary power, mostly for public entertainment reasons, I can only concurr with this.

For an event we will usually have a list of who wants what supply and where and I'd say 50% of them expect to plug more in than they ask for. Catering wagons are always wrong and we'll try to allow double for them.

Quite often the layout of the event is planned around power and it's quite common to supply 16A to several users when they say they have only small loads and then when they see a 13A socket spare the heavier loads appear.

We had one regular guy with an engraving machine rated at 150W and a fluo tube. suddenly he turned up with an oven and other machinary to make encapsulated items and didn't understand when we said he had to stop using them.

Me too!

Did you ever meet the Pot Noodle wagon? 2 x 63A TP&N feeds for the instant hot water boilers!

Caters were always the bain of our lives. Had one guy complain that there was 'something wrong with our power' because his 'fridges weren't cold .... then we watched... girls filling the 'fridge with pop cans that had been out in the sun for hours.... as fast of other girls were selling them!


SimonH2 - yes, temp system do use MCBs/RCBOs - and lots of them! Our "customers" are never to blame though, an MCB never trips because they are pulling to much juice, its because our kit is faulty! One 16A feed to a catering wagon was clamped at over 80A ... its surprising how long an 16A MCB will hold in even at that current.

 

[JohnW2]

not heating the element ... not heating the kettle ... only heating the exact amount of water that fills the mug.

That's true, but the microwave involves some potentially lossy 'electronics' (power supply) - so, without doing the experiment, I suppose one can't be sure which one would 'win'. What I do know is that the difference (in whatever direction) would not be enough for me to lose any sleep over, so I probably won't bother with the experiment

Kind Regards, John

 

[winston1]

I'm told the most economical way to boil water for a mug of tea is to put it in the microwave.

A microwave oven is only around 55% efficient so that is not true.

The most economic (and dangerous) way to boil a mug of water is two carbon rods in the cup connected to the mains.

 

[JohnD]

A microwave oven is only around 55% efficient

how efficient is a kettle when it has to raise 250mm of water, plus the heating element, plus the vessell?

 

[winston1]

how efficient is a kettle when it has to raise 250mm of water, plus the heating element, plus the vessell?

The heating element and vessel require a lot less calories per gram than water. I'd say a kettle was much greater than 55% efficient.

 

[JohnD]

The heating element and vessel require a lot less calories per gram than water.

eh?

 

[JohnW2]

eh?

I am aware of no solid or liquid material/substance which has a higher specific heat than water - so, for once, I think that winston is actually right.

Kind Regards, John

 

[SUNRAY]

Me too!

Did you ever meet the Pot Noodle wagon? 2 x 63A TP&N feeds for the instant hot water boilers!

No. But we did have a service which asked for a 63A supply and on arrival it required 63/3. Some of the heating elements were 3ph delta and fans 3ph. The genset allocated to them (not by us) was single phase and marginal size like 15KW.

Caters were always the bain of our lives. Had one guy complain that there was 'something wrong with our power' because his 'fridges weren't cold .... then we watched... girls filling the 'fridge with pop cans that had been out in the sun for hours.... as fast of other girls were selling them!

Well if it's any consolation I have come across a selection of 'widow makers' over the years which have been made by fully qualified electricians.
Such as this:
View attachment 149171
Removed from the 'load' end of a catering trailer.
For infothis was a 16/3 using 3 pins for a 1ph with 2.5mm² flex, other end was a 32/1 and usually used on a 5.5KVA genset. I measured the load at 55A IIRC, hence the heat damage.

This particular wagon had asked for 32/1 and the cable was laid in for them prior to their arrival. They turned up, hooked up, went looking for the MCB and flicked it on. They soon came looking to complain there was something wrong.
And to clarify this was removed from the wagon end of the cable, so part of a widowmaker. Note the heat damage.

 

[winston1]

I am aware of no solid or liquid material/substance which has a higher specific heat than water - so, for once, I think that winston is actually right.

Kind Regards, John

As I said before I am usually right. I engage brain before hitting keyboard.

 

[mikeey84]

I am aware of no solid or liquid material/substance which has a higher specific heat than water - so, for once, I think that winston is actually right.

Kind Regards, John

Hi John, just for info, helium and hydrogen gas both have specific heat capacities in excess of water (and higher than steam)

 

[SUNRAY]

As I said before I am usually right. I engage brain before hitting keyboard.

WINSTON Do you really want me to start picking holes in everything you say again?

 

[HERTS P&D]

As I said before I am usually right. I engage brain before hitting keyboard.

Winston, are you female, as that is a female statement.



Andy

 

[Mottie]

Winston, are you female, as that is a female statement.



Andy

Have you been mixing with Bodd again? You’re starting to talk like him now.