metric wire

[jbolen]

We are having problems verifying ampacity of European wire in Iraq, for motor loads ex. 24 amp motor x 125% = 30 amps what size wire? not awg

 

[aftershock]

Would this link help?
http://www.rbeelectronics.com/wtable.htm

 

[dbuckley]

You need to look in the tables at the back of BS 7671. Not available online without cost as far as I know, sorry.

But you wont be multiplying European amps by 125%; theres something wrong with American amps whereby if you use them for three hours or more something gets broken. Europe doesnt have anything like that. An amp is an amp and its value doesn't change over time or depending on the load

From memory(!) for 24 amps you can use 2.5mm SWA, or 4mm PVC sheathed unless there is some complicating factor causing heat build up or excessive voltage drop, for example. But its some years since this memory was calibrated, and the book is at home, where I'm not - so get 7671 and verify it.

 

[tom baker]

The reason we add 125% to continuous duty motors (some motors its more) is the heat from that duty affects the operation of the branch circuit and overload devices. The larger wire acts as a heat sink to keep the device from tripping. Mike Holt had a great code change in ARrt 210 and 215 related to this - a neutral does not have to be increased in size 125% as its not connected to an overcurrent device.