What does "450/750V" on a cable REALLY stands for?

[hidex1213]

Hey guys.
Please allow me to be honest first - I do not have any engineering background at all (tho I graduated with a biochem degree, that's very different) and found myself working in a electrical supplies company now.

I've been trying to look up the meaning of "450/750V" or "0.6/1kV" (ie. U0/U, according to some articles) on the cables that I sell (obviously we sell LV electrical products) but I've been given various answers...
Some say that the U0 is the VDC rating while U is the VAC rating; while the others say U0 being the operational (or "regular", I guess?) rating and the U being the peak rating.

Would anybody here please verify this for me?
I know it's probably a really obvious question but it's been bothering me quite some time...
Please help if you don't mind. http://www.------.org/forums/forum/i/expressions/face-icon-small-smile.gif

 

[Knobhead]

Have a look at BASEC - British Approvals Service for Cables

 

[lamb]

U is line voltage (phase to phase)
Uo is phase voltage (phase to earth)

 

[hidex1213]

Thank you guys!
But there always seems to be a "magic" factor of 0.6 between U0 and U (300/500V; 450/750V; 0.6/1kV...)
so my follow up questions are...
Why 0.6?
What causes the discrepancy between U0 and U?
What about for a single phase power? would U0 = U?

 

[Knobhead]

Line voltage is phase voltage X √3 so it’s always a fixed ratio

 

[hidex1213]

Thanks！
I'll now go and google up what's line voltage and line-earth voltage.
Thank you!

 

[stevie2011]

i never asked in college but now its bugging me. √3 x 230 doesn't come up to exactly 400 v and same for the other ratios √3 = 1.732050808 but 400/230 = 1.739130435 have engineers just rounded the voltage to a more usable number or are there some other factors? knowing that 230v is just the RMS of the wave form. The voltages brought up in this thread also bring up questions for instance 750/450 = 1.666666667 quite far from the √3

i hope someone knows what i'm on about haha.

 

[Knobhead]

View attachment 8103

What would you have the cable manufacturers print on the cable?

577.3503/1000V
433.0127/750V
288.6751/500V

The figures are rounded for convenience!

 

[Knobhead]

Don't even know if you can still get 300/500V grade now.

I would never use anything under 600/1000V

 

[stevie2011]

yeah i thought it might be rounded, makes sense just wanted to know what the exact values were supposed to be because I'm being a nerd