8.5kw shower wires in 4mm, burnt terminals

[dmxtothemax]

The fact that only one wire was burnt suggests that the problem came from a loose/ faulty terminal or connection. Even thou the cable size is not adequate, it alone did not cause this, a bad connection caused this !

 

[Strima]

slightlyoff topic, but hre's something that has been bugging me for ages.

when applying the temp. factor ( 1.2 ) to your loop impedance as per osg., why apply it to the whole Zs value and not just to the R1+R2, when the supply cable from sub-station is never going to approach anything like 70 deg. ????

thoughts???

Which page of the OSG is the calc on?

At a guess they're trying to aire on the side of caution???. The actual design formula is Zs=Ze+1.2(R1+R2).

Problem is you get two different results. I've just plucked some numbers out of the air, Ze-0.35, R1+R2-1.12.

Using the design calc I get 1.274 ohms. Zs=Ze+1.2(R1+R2)

Using the OSG calc I get 1.344 ohms. Zs=1.2(Ze+(R1+R2))

So in some cases the incorrect CSA cable could be used, although this would only mean going up a size.