Appliance fuses

[Ray Tay]

sparkwright, 'Rightly or wrongly I was taught it good practice to fit a fuse as near to the rating of the appliance, ie slightly larger than the appliance rating, as well as it being adequate for the cable size.'

Thank you. I was taught the same way.

Risteard, 'I think it's fair to say that Ray Tay hasn't a clue what he's talking about.'
I think fair to say Ray knows exactly what he is on about. Think, do not go by what all the others do. Some advice, If an appliance draws 4A do not put a 13A fuse in the plug. You are supposed to be trained to work out fuse sizes.

 

[sparkwright]

Come to think of it, when you used to buy a pack of fuses from Woolworths, the sizes on the packet corresponded to the appliance and it's rating, not it's cable size.

But I'm not saying I agree with all your statements!

 

[EFLImpudence]

Raytay -

Doyou have a mains inspection lamp?
If not, pretend you have.

What size fuse have you put in the plug?



What are the design criteria for a circuit and in what order should they be applied?

 

[EFLImpudence]

Another question:

How do you feel about 433 - omission of overload protection?

 

[Ray Tay]

sparkwright, 'But I'm not saying I agree with all your statements!'
What you wrote here agrees with all my statements 100%..''I was taught it good practice to fit a fuse as near to the rating of the appliance, ie slightly larger than the appliance rating, as well as it being adequate for the cable size.'

The appliance fuse rating took into account the cable size. Woolies had a whole raft of fuse sizes. Or you went to the local electrical shop, when they were on each corner, and he would size it for you. If you told him the appliance name, like a Hoover super-dupa iron or whatnot, he would know the fuse size.

A now standard 1,800 watt kettle only needs a 10A fuse, which are freely available.

 

[Ray Tay]

EFLImpudence, you are trying to be clever aren't you? Anyone on looking at the appliance badge can figure out the fuse size. If the appliance draws 6A you do not put in 13A. No doubt you would.

 

[bernardgreen]

Anyone on looking at the appliance badge can figure out the fuse size

Lets say the appliance badge says 240 VA

Question to Ray Tay only What fuse would you use for that ?

 

[EFLImpudence]

So, what size fuse for a 100W inspection lamp?

Then, what if you change the lamp for a 10W LED one?

 

[Ray Tay]

bernardgreen, appliance badges have the loading.

 

[kai]

I consider it good practice to reasonably match the fuse size and the appliance in mind. There is no valid need to max out the fuse rating just because the circuit cable can cope with it!!!

 

[Iggifer]

From the IEE Code of Practice for Inspection and Testing of Electrical Equipment

15.14 Plug Fuses

The fuse in a plug is not fitted to protect the appliance, although in practice it often does this. The fuse in the plug protects the flex against faults and can allow the use of a reduced csa cable

Although two standardised plug top fuse ratings have been adopted, the fuse recommended by the manufacturer should be fitted. Fitting a smaller fuse, such as a 3A fuse, may give problems later on. Many items of equipment have considerable inrush current when first energised due to the starting surge of motors, the inrush currents of transformers, of the charging currents of electronic power supplies.

 

[EFLImpudence]

I consider it good practice to reasonably match the fuse size and the appliance in mind.

Fair enough. Any reason for thinking this is good practice?

There is no valid need to max out the fuse rating just because the circuit cable can cope with it!!!

There is no valid need to min out the fuse rating just because the appliance is smaller than the cable can cope with!!!

Would you down-rate the MCB if you fitted a smaller shower?

 

[Iggifer]

There is no valid need to max out the fuse rating just because the circuit cable can cope with it!!!

There is no valid need to min out the fuse rating just because the appliance is smaller than the cable can cope with!!!

Would you down-rate the MCB if you fitted a smaller shower?

Probably

 

[EFLImpudence]

As long as you don't charge - ok.

 

[Iggifer]

As long as you don't charge - ok.

Haha I didn't mean I would! I meant Kai would. God, I need to be clearer with my responses.