AMPS????????????????

[FERMAC]

Hi,

Hope someone can help, can anyone explain Amps to me? Or recommend a good website or book that will?? I have asked for advice in my local DIY store but they didnt seem to have much of a clue either!!!!!!!!!!!!!

Am I right in thinking the Amp value that comes on everything for example, cable (47A), fused switches (13A), junction boxes (30A) the maximum amount of current they can take, before melting, catching fire etc???

Am I also right in thinking that when choosing what junction boxes etc to use, do I need to look at the Amp rating of the appliance that it will be supplying and make sure the rating of everything else equals or is bigger than this??? or should I make sure they all have the same amp rating???

Any help would be appreciated!

Thanks

 

[Al-Glasgow]

http://www.thediyworld.co.uk/amperage.html

hope this helps you

Al

 

[Steve]

The cable should be the highest rated thing in the circuit. It should be rated higher than both the MCB and the expected load (subject to de-rating due to cable run factors)

The MCB should be rated slightly higher than the expected load (subject to diversity if applicable), but it should be rated lower than the cable, so the cable is protected.

For example, I am installing a shower that draws 9.5Kw at 230V. This is 41.3A. My cable needs to be rated at 41.3A or above (assume 6mm run in free space, this is 47A i think), and my MCB needs to be rated between 41.3A and 47A. So 45A would be a good choice.

Circuit design is about a lot more than maximum/minimum ratings of items, as i hope i have clarified above (cable run factors, diversity etc)