Heavy Duty Extension cable idea for garden and pool use

[overskilled]

I was talking a fixed supply (properly cleated and made off) to a commando socket to protect from mechanical damage etc, I was reading it in terms that the pool kit already had supply leads fitted from factory. if not then yes suitable H07RN-F cables

 

[NDG Elecs]

Get some 1mm h07 pond cable and coil it in the water...the water will be hot in no time!!

Actually, dont do the above. It was a joke. 3kW running for long periods on a plug top will get pretty damn warm. A dedicated 16/20 amp supply would be a much better solution.

 

[NDG Elecs]

Plus one was rated 3kW at 230V so actually pulled more than 3kW at our actual voltage of ~250V

Dave, you come across on here as a knowledgeable sort. Got a question re the above.

You are basically saying at 250V it would be pulling 3.25kW. That is 13A × 250V = 3.25.

I was taught to work this out as 3kW ÷ 250V = 12A. 3kW ÷ 240V = 12.5A etc etc.

So you are using the current (13A) as a constant whereas I have used the load (3kW). Just wandering why? And was my teacher siht!!

Thanks

 

[davesparks]

Dave, you come across on here as a knowledgeable sort. Got a question re the above.

You are basically saying at 250V it would be pulling 3.25kW. That is 13A × 250V = 3.25.

I was taught to work this out as 3kW ÷ 250V = 12A. 3kW ÷ 240V = 12.5A etc etc.

So you are using the current (13A) as a constant whereas I have used the load (3kW). Just wandering why? And was my teacher siht!!

Thanks

You'll notice I didn't actually put any value to it, just said that it would draw more than 3kW at 250V. The actual current at 250V will be around 14A if the load is 3kW at 230V

Neither the current nor the power is a constant. The resistance of the load is the constant (for the purpose of this it can be considered constant but in reality it changes with temperature)
So if the power is 3kW at 230V you get a current of 13.04A (P/V) and a resistance of 17.64ohm (V/I)
Therefore at 250V you get a current of 14.17A (V/R) and a power of 3.54kW (I*V)

The confusion comes in when people think that a conventional load has a constant power when it is actually a constant resistance. If you look at the power ratings on things like electric showers you will find the have different rated power at different voltages.

 

[NDG Elecs]

Cheers Dave,

I forgot about resistance being a theoretical constant. I should brush up on the basics occasionally!

 

[wymondhamcables]

I believe I would be breaking the forum rules to direct to a specific company or product but there are people out there who could make exactly want you want.