Stumbled upon...

[ban-all-sheds]

... http://www.electrical-installation.org/wiki/Main_Page

looks interesting.

 

[spalding1sparks2]

looks to much for this time of night date I saw 2003 when it was prepared
re Low votages 220V up 230V 240V down to 230V well thats been done on paper but I still find 240V -246V in Lincolnshire so thats fine! I have to calc at 230V ???? welcome to the real world must be some kind of inflation

 

[ban-all-sheds]

I saw 2003 when it was prepared

"This page was last modified on 14 June 2010, at 12:38."

"The Electrical Installation Guide (EIG), was until 12/2009 an exclusive Schneider-Electric publication distributed through printing and internet (ISBN: 978.2.9531643.3.6, version 2010). This new WIKI-EIG is now allowing all external contribution for improvement and update. "

re Low votages 220V up 230V 240V down to 230V well thats been done on paper but I still find 240V -246V in Lincolnshire so thats fine! I have to calc at 230V ???? welcome to the real world must be some kind of inflation

BS 7671 also requires you to calculate at 230V, and has done for over 2 years.

 

[spalding1sparks2]

Yes I agree. That was my point

 

[ban-all-sheds]

Sorry - I thought you were commenting on that site.

 

[bernardgreen]

BS 7671 also requires you to calculate at 230V, and has done for over 2 years.

A resisitive load ( heater etc ) of 1 Kwatt at 230 volts will take a current of 4.35 amps and has a resistance of 52.88 ohms

The same resistive load when supplied with the UK maximum supply of 253 volts will take 4.78 amps. 10% more than the calculated value for that load.

If the design is to be safe at 253 volts shouldn't the calculations be for 253 volts ( 230 + 10% ) to ensure that no cables are carrying more than their permitted maximum current.

Or do, as I suspect, the regulation / formula allow for this and calculate currents less than the actual capability of the cable.

DIYers... do NOT take that as a reason to go beyond the maximum rated current for a cable. There are more complex equations involving time in the calculation.