This subject seems to always causes much confusion during our PAT Training courses - so thought about covering this in our first post.
During the course our advise is:
In a working appliance, if you find a 3 Amp or 5 Amp fuse then there is no need to change this. Just leave this in place.
If the power rating in leass than 700 Watts then change the fuse to a 3 Amp one. If the power rating is more than 700 Watts then leave the 13A fuse in place.
Considering that these instructions are based at beginners to PAT testing, it should in theory not cause any confusion. However when we pose the following question, nearly everyone gets the wrong answer.
"You find a 5 Amp fuse in a plug and the appliance has a power rating of 900 Watts. Would you leave the fuse in place or change it to a 13 Amp one".
Most delegates say that the fuse should be changed to a 13 Amp one as the power rating is more than 700 Watts, completely ignoring our advise to leave a 3 Amp or 5 Amp fuse in place.
I am really puzzled by this response. Is it because people assume that a 13 Amp fuse provides a better protection than a 3 Amp or a 5 Amp fuse?
I will be grateful for any suggestions on this topic.
Most people with little or no electrical knowledge would not know how to work out current flow. A rough guide should be applied here by dividing the power rating by 250. If the answer is less than 5 then the 5 Amp fuse should be left in place. e.g. 900 divided by 250 is less than 5, so leave the 5 Amp fuse in place.
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