Help needed Please!


Old 07-15-13, 04:21 AM
Thread Starter
Join Date: Jul 2013
Location: England
Posts: 1
Help needed Please!

Hiya all i have a problem which i cannot seem to solve it may be simple but im not really an electrical person.
I have a 400v, 32Kw induction motor it is supplied via a short circuit current of 800 A . In short i need to determine, the rated current of a BS 88-2 fuse for circuit protection.

What current carrying capacity of the circuit cunducters what do you recommend?

i know these questions may not be clear but anything helpful would be much apreciated.
Thanks hope to here from you all soon.
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Old 07-15-13, 07:00 AM
Tolyn Ironhand's Avatar
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Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,284
Welcome to the forums!

This is mainly a US site that references the US National Electrical codes and electrical standards, but we may be able to help.

You did not post if the motor was three phase, but at 400 volts and 32KW size, I will assume it is.

A 32KW three phase motor running on 415 volts (voltage standard in England) will draw about 50 amps:
( 32000 / 1.73 x power factor (I used 0.9) x 415 volts)

Given that amp draw I would suggest #6 copper or larger.

Also based on the amp draw, and the information I found here:,d.aWM It appears that a 125 amp standard BS88-2 fuse is correct if the motor is only used intermittently. If the motor will be used frequently, than a 100M125 fuse is the correct choice.

You may be also required to provide overload protection for the motor.

Disclaimer: This info it out of the normal for me. You should double check any, and all of it, with a local electrician.

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