Does this need an RCD?

[JohnnyG]

A customer required a new external socket outlet for power tools, lawnmowers and the like so I connected one to this light switch in a shed for them as it only switches 2 fluorescent tubes so it probably has enough spare power and the cables inside the trunking looked quite big.
Should I fit an RCD though, it's all inside the shed so I'm guessing it doesn't need one?

ps. I didn't bother doing the socket up as it's quite high up and it won't get wet in there anyway.

Untitled

• JohnnyG
• 27 Feb 2010
• 1

*The above post may not be true.

 

[Lectrician]

Saw this done in a stable once - kettle took ages to boil apparently

 

[Taylortwocities]

Saw this done in a stable once - kettle took ages to boil apparently

Why, was it at the top of a very high mountain?

 

[holmslaw]

..

 

[Taylortwocities]

The higher the mountain the lower is the temperature at which the water will release water vapour ("boil").

So your egg takes longer to cook on Margherita Peak.

 

[electronicsuk]

The higher the mountain the lower is the temperature at which the water will release water vapour ("boil").

So your egg takes longer to cook on Margherita Peak.

That doesn't make any sense to me. If the boiling point of water is lower at high altitudes, then it follows that less energy will be required to heat the water in reaching the boiling point, and the kettle will boil quicker.

 

[Taylortwocities]

The only factor that determines the boiling point of water at any altitude is the barometric pressure (the altitude itself doesn't actually matter, it's just that at higher elevation, the barometric pressure usually drops).

However, water will boil at two different temperatures at the same elevation if you are in a high pressure weather system instead of a low pressure system.

So (assuming the same barometric pressure)
Water boils at 100 °C at sea level
it boils at 90.82 °C at approx 10,000 ft

So when your water heats up and starts releasing water vapour thats as hot as it will get. So, pop your egg in for 4 minutes at sea level and its done, at 10,000 feet it will probably take a minute more.

It will take less time to reach the boil point, but that point is not so hot.

The big issue is if you are having to boil water for sterilisation reasons. Many bugs will live on at 90ºC but will peg out at 100ºC.

EDIT: I wish I hadn't made an offhand remark now!

 

[holmslaw]

..

 

[Taylortwocities]

Its really trying to say (as you know) that the boil point change is a result of barometric pressure change, not a factor of altitude.

There may be a transient atmospheric condition where the pressure is higher up a mountain than at the base.

Anyway, nothing to do with the point of the topic.

 

[1john]

assuming the feed to the kettle was from the bottom of the mountain, wouldn't the volt drop on the long extension lead effect the performance of the kettle

 

[mikhailfaradayski]

at higher altitudes, there is less gravitational pull from the earth experienced by the water, therefore the water weighs less. Would the H2O therefore require less energy input to change its state from liquid to gas?

 

[maguire]

HI The hell with all that just take a flask fcs

 

[Taylortwocities]

Ahh, with a flask you have additional problems. The sealed container will have been sealed at 1 ATM. You will now be climbing the mountain where the pressure will be much lower.
Could be tricky.

Now - brainboxes -

lets suppose you take two flasks up the mountain
One filled with cold water at 5ºC
One filled with hot soup at 70ºC

As you climb the mountain the outside pressure will decrease.
Which flask will be the first to explode?

 

[maguire]

Em None the soup flask will implode
Mac

 

[ban-all-sheds]

Which flask will be the first to explode?

FFS, isn't it obvious?

Any fule kno it's the one on the conveyor belt - how can you be so thick?