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7,300 Watts supplied on a 2.5mm2 T&E.

Zoomup

Yes a 2.5mm2 T&E cable can supply a 7,300 Watt instantaneous water heater at 240 Volts. I came across this today. The supply was from a B32 M.C.B. So why do we use bigger cable than 2.5mm2 if it will do the job?

The run was about 5m maximum. 

Z.

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    Zoomup: 
     

    Perhaps the pointed headed men in white coats at the I.E.T. could consider a Cfut correction factor. We already have Ca, Cc, Cd, Cf, Cg, Ci, Cs to name but a few.

    Cfut cold refer to the functional utilisation time conditions. So, if applied, it would allow a large load to be supplied by an otherwise inadequately sized cable, but only for a short period of time, before the cable becomes dangerously hot and starts smoking. This approach will save materials and money.

     

    Z.

    No need - the concept is already in BS 7671 - see 533.2.1 3rd paragraph (although done by adjusting the design current rather than by a correction factor).

       - Andy.

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  • 0

    Zoomup: 
     

    Perhaps the pointed headed men in white coats at the I.E.T. could consider a Cfut correction factor. We already have Ca, Cc, Cd, Cf, Cg, Ci, Cs to name but a few.

    Cfut cold refer to the functional utilisation time conditions. So, if applied, it would allow a large load to be supplied by an otherwise inadequately sized cable, but only for a short period of time, before the cable becomes dangerously hot and starts smoking. This approach will save materials and money.

     

    Z.

    No need - the concept is already in BS 7671 - see 533.2.1 3rd paragraph (although done by adjusting the design current rather than by a correction factor).

       - Andy.

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