Corsair Modular Power supply cable - and why Americans don't drink tea!

[peterb]

There have been a number of slightly adverse comments (including my own) about the quality of the modular cables supplied with Corsair PSUs.

I have been having another look at the cables that came with my HX520, and I have revised my opinion - it isn't that the quality is poor, they are just different from what we are used to in the UK/EU. Why is this?

The US power distribution is based on a 115V system, which has both advantages and disadvantes. The main advantage is safety - a 115V shock is less likely to be lethal than a 220/240V electric shock. That is sometimes further reduced by centre tapping the supply transformer to earth, so the maximum potential from each conductor to earth is just over 50V (and this principle is widely used in this country for portable electical appliances on building sites - those yellow transformer boxes)

What does that mean in real life? Well if you go into an American hardware store, in the electrical section, the mains wires sold for extensions are different in construcyion from UK/EU weiring. Firstly the insulation doesn't have to be (and often isn't) as robust as EU cables - after all, it only has to insulate against 115V. Secondly, the conductors have to be a thicker - why? Because a 1Kw heater in the UK on 230V will take about 4 amps - on a 115 volt system it will be 8 amps, so to reduce the voltage drop (which will be more significant on a 115V system anyway) the wires have to be thicker, and US cables seem to use fewer thicker starands in the mains cables. I believe it is this type of cable that Corsair use for theit modular connection cables, hence the apparant lower quality.

What has this to do with making tea? Leaving aside the historical tendency to soak perfectly good tea in salt water (in Boston) good tea needs a large quantiy of briskly boiling water. Electic kettles in the UK are generally 2.5 to 3 Kw - whicjh on a 230 volt system is between 10 and 13 amps. But on a 115V system, you are looking at 20 to 26 Amps, making the cables thick, and frankly, lots of American house electrical infrastructure isn't up to it - so no kettles - no tea. Hoever those little coffee pots are fine as they produce a dribble of hot (90C) water over about 5 minutes - perfect for coffee.

So those that might be put off by Corsair cable quality - don't be - and those travelling to USA - now you know why it is almost impossible to get a decent cup of tea.

(US houses do have a 230V system, but normally for fixed appliances, like Aircon, Cookers, Immersion heaters, tmble driers - not for portable appliances - this also explains why front loading automatic washing machines are rare - most heat their own water - using a failrly high power heater. Us machines use a hot fill and crude temperature control - no heater built in)

[shaithis]

Perhaps my old school knowledge is rusty (its been 17 years!) but I thought that if you halved the voltage, you double the current (for the same power)?

And it is current that kills, not voltage? Which would make the UK supply safer then the US.

[SiM]

Good post!

[peterb]

Perhaps my old school knowledge is rusty (its been 17 years!) but I thought that if you halved the voltage, you double the current (for the same power)?

And it is current that kills, not voltage? Which would make the UK supply safer then the US.

For a given wattage - halving the voltage does require double the current (for a given fixed resistance - where I is current, V voltage and R resistance I=V/R.

Consider the human body - dry skin resistance is about 200,000 to 500,000 ohms - so if you put you fingers across a 1.5 volt torch battery, the max currebt will be about 7.5 micro amps - you wont notice it. At 115 volts the current will be about 10 times that amount - about .75mA - which you will notice. At 230 volts this will be about 1.5mA - which you certainly will notice. However there are other effects. Mains voltage is alternting current, and at voltages above about 75, this overcomes the skin resistance, and that insulation resistance drops - causing more current to flow. $ma is enough to kill, if you are unlucky - particularly if it acropss the chest (hand to hand), as the AC current can stop the heart. It also causes the muscles to spasm so you cant let go (I speak from experince - luckily only on one hand where I still have the scar tp prove it) - and 230V 50 Hz is abouyt the worst combination. Higher valtages can (if you are lucky) throw you off the conductor - but still give you a nasty burn though.

Bottom line is don't work on live high energy ccts above about 55V unless you know what you are doing! (Note the high energy bit - static electicity shocks can go up to many thousand of volts, but the current from a static shock is very very low, so while you feel it, it doesn't do any harm - to you - death to some electronic components though)

[switchmode]

Perhaps my old school knowledge is rusty (its been 17 years!) but I thought that if you halved the voltage, you double the current (for the same power)?

And it is current that kills, not voltage? Which would make the UK supply safer then the US.

Voltage is what makes the current flow more voltage more current for the same load so you get more current if you get a shock with 230 Volts than 110 volts. Its current across the body thats most dangerous if you touch an earthed metal case with the left hand and get a shock on your right hand thats more likely to be lethal than if the current goes down your leg to earth I was always told to only use one hand if connecting anything live when I was an electrician. even low voltage can kill if you are wet.

[s3ds]

i dont like the all black wires lol
but it aint stopped me using it
its a good psu imo

[Andydigital]

I thought AC threw you off and that's why AC is used in the first place, its DC that you cant let go of isn't it?

[moogle]

Perhaps my old school knowledge is rusty (its been 17 years!) but I thought that if you halved the voltage, you double the current (for the same power)?

And it is current that kills, not voltage? Which would make the UK supply safer then the US.

yep, and more efficient as there's less loss of power down the line.

[Thorsson]

I have a stovetop kettle, so I can still have my cuppa, but you're right, electrical kettles are like hen's teeth (they do exist though). And I love the explanantion on why their washing machines are so stone age.

[switchmode]

AC is used as its easy to change the voltage for use, ie high voltage transmission and the dropped down with a transformer for use, transformers are just coils of wire basically. 110 Volt or 230 Volt both just as efficient you just need thicker cable for the same power with 110 volt. the national grid use thin transmission cables at very high voltage for power lines low voltage would make the cables to heavy to use. AC Alternators which make the AC are simpler than DC as well I think.

[peterb]

I thought AC threw you off and that's why AC is used in the first place, its DC that you cant let go of isn't it?

AC makes the muscles contract (and vibrate - it is most unpleasant) so if you touch a live conductor with the palm of your hand, your hand will close on it. If you touch it with the back of your hand, your hand will pull away.

(My story - I was removing an extension lead on a washing machine, having switched off and unplugged it at the other end. Undid the screws of the inline connector and turned it over to slacken the cord grips. That was when I discovered that I had switched off and unplugged the wrong plug. My hand closed on the connector, but luckily I was standing on dry lino and all three conductors were in one hand, so it only affedt that arm (my left one) I am right handed so I was able to grab the cable with my right hand and pull it away from my palm. I suppose I was connected for about 10 to 15 seconds. This was 18 years ago - I still have the scars at teh three contact points on my hand to remind me... needless to say, I have never done that again!!)

AC is a far more efficient method of power distribution (as switchmode succintly states in the previous post), particularly 3 phase (which I'm not going into here!) and is essential for induction motors to operate correctly. AC generators are much simpler than DC dynamos and regulation is much more precise.

(Rather got off the topic of Corsair modular cables and American Tea!)

[Blackmage]

what is a toaster?(AC/DC) i was shocked by one sticking the knife(butter knife) in it, while on(don't ask). my was body shaking/vibrating like crazy, luckily for me we have a tiled kitchen so i think that earthed me.

For about 3 seconds i couldn't drop the knife.

[peterb]

a toaster - like all domestic appliances - runs on AC (although being a purely resistive load, it would work on DC as well) The sysmptons you describe are typical of an AC mains shock!

[BUFF]

The US power distribution is based on a 115V system, which has both advantages and disadvantes. The main advantage is safety - a 115V shock is less likely to be lethal than a 220/240V electric shock.

it's the amps that kill you not the volts - so you've got it the wrong way around ...

[switchmode]

it's the amps that kill you not the volts - so you've got it the wrong way around ...

Sorry BUFF the current flowing through you, is what kills you yes. But the current that flows is dependant on the voltage more volts more current so 230 volts is more likely to kill than 115 volts.
Thats for the same situation. 50 volts can kill even less but if you are very dry skinned or standing on a rubber mat so you are not grounded it probably won't.

High voltage static electricy dosn't kill because as soon as you touch it its voltage drops to o Volts no power behind it. the charge "static" leaks to earth so no problem.

[BUFF]

it's all irrelevant anyway as a reason for the cable construction as they are on the output side of the PSU so:
a) it's the same all over the world - 12V, 5V, 3.3V etc. not 115V or 230V
b) they are made in the Far East anyway ...