833A (GU-48) Amp

[Mike H]

High current wire tends to have thick insulation anyway, if that's what you meant. (Phil that is, not Nick)

 

[pre65]

I've found some thicker wire in the shed.

It came out of a 6.5 litre V-8 diesel Chevrolet ambulance.

[Mike H]

Sortified!

 

[jack]

Thinking about the wire rating (1000V & 4.5A), does the current capacity go up as the voltage comes down ?

Current rating is for the wire in air (i.e. not in the centre of a bundle).

P = I^2 x R, so its the resistance of your bit of wire times the square of the current - the voltage bit is just how good the insulation is. So minimum R. The high current HV stuff I do uses 20 or 25 sq mm cable. If you want it flexible, then welding cable is the stuff to use, otherwise its a complete b*itch to work with...

The bit about current rating being for wire in unrestricted air is important for power considerations - I used to work doing theatre lighting when I were a lad, and more than once we had a bundle of cables that just fused into a lump, even though individually they were running well below rating - the ones in the middle just cooked...

I have worked with 833s and used 12 or 16 AWG wire for the heaters...

Cheers

ps. I have two DOA 833s in my "Hall of Fame(Infamy)" (Finfamy?) Arrived from the USA with internal damage, though not outgassed.

[pre65]

ps. I have two DOA 833s in my "Hall of Fame(Infamy)" (Finfamy?) Arrived from the USA with internal damage, though not outgassed.

Did you get compensation for them from the seller ?

My drills came lunchtime, so there's no excuse not to get on with mounting all the capacitors on the bottom deck.

[pre65]

High current wire tends to have thick insulation anyway, if that's what you meant. (Phil that is, not Nick)

What I wos thinking was, is it about current or watts.

ie 10A & 10V = 100W

but 10A & 240V =2400W

So, would 10A rated wire be OK with both the above ? (in free air )

[Mike H]

But there's no high Voltage involved is there? Cos it's for the 833A heaters. Which aren't at high Voltage.

So it's just the current capacity thing to worry about.

 

[pre65]

But there's no high Voltage involved is there? Cos it's for the 833A heaters. Which aren't at high Voltage.

So it's just the current capacity thing to worry about.

So, the current capacity of a wire is totally independent of the voltage ?

[shane]

The rating of the wire is based on how hot it gets if you pass a current down it. The heat generated is dictated by the resistance of the wire and the size of the current. Using ohm's law, heat generated (power) = i2r (can't do superscript). Voltage is irrelevant.

[pre65]

OK.

I understand.

[Mike H]

In other words . . .

So, the current capacity of a wire is totally independent of the voltage ?

. . . strange as it may seem, yes

Wires should have 2 specs, current carrying capacity and max. Voltage for the insulation. What you're most interested in in this case is the max. Amperes part.

As the total is 10A, and there are 3 terminals for each polarity on the SMPS, you could use 3 pieces of 6A mains cable wire in parallel for each polarity. Just as an idea.


 

[Nick]

I think I will give up posting.

[shane]

If you think of the power rating of a resistor, that's dependant on current rather than voltage as well. Doesn't matter if you've got 1v on one end and 0v on the other, or 1kV on one end and 999v on the other, the power dissipation is the same. Same thing applies to a piece of wire.

[pre65]

I think I will give up posting.

Some of us just have difficulty in understanding occasionally.

[jack]

1mm twin & earth (6242Y) is rated at 14A RMS. If you are happy with solid core, use that. Its cheap as chips and you've probably got some already (you can always find bits buried in your walls...)