1Amp 240V Cartridge Fuses from here

[Yorkie]

Can't find 1 Amp fuses locally for 13A 3-pin plugs for use with radios, so it's always a temptation to use what's to hand.

I've just bought 20 from the link below at £1.73 for ten, post free.

17.3p per fuse seems very reasonable. Came by return of post:

http://www.amazon.co.uk/gp/product/B0090...TE_3p_dp_1

Hope that might be useful to someone.

[AlanBeckett]

Good find that David, I've ordered 1s, 2s and 3s.

Alan

[Murphyv310]

Hi.
CPC normally carry these in stock too!

[ppppenguin]

This may be a daft question but do 1A fuses really give any useful extra protection over 2A fuses?

Under short circuit conditions there is no useful difference. Under overload conditions there might be but is it a useful amount? I think useful might be defined as stopping something burning out, such as a mains tx. On the margins a 1A fuse may give an occasional extra save but I think this will be rare.

This is largely gut feeling. If anyone can back an argument for or against with real numbers that would be useful.

[Terry]

I think I'd agree with Jeffrey here but the discussion also reminds me of the day my brother managed to get a 60mA 1¼" fuse directly across the output of our 12V PSU ...

Much to his surprise - and mine, rather than blowing, as one might expect, it imitated a festoon bulb, glowing a cheerful orange ...

[ppppenguin]

Which is because its resistance was so high that not enough current would flow to give a quick blow.

Typical radio might take 100 to 200mA. If it takes 10x that under fault conditions a 1A fuse will take a long time to blow. Without the blow time vs current curves to hand I'd guess hours not minutes. I doubt that will protect the main tx.

somebody could do an experiment with a mains tx. Put a shorted turn on it and measure the primary current. Likewise short a heater or ht winding. Obviously only for a second to get the reading. Beyond that you could do a test to destruction and time how long it takes to fail or catch on fire. Obviously some transformers are more fragile than others but this could give an indication.

I don't think any other faults are likely to give enough excess current to even remotely trouble a 1A fuse.

[Terry]

... the discussion ... reminds me of the day my brother managed to get a 60mA 1¼" fuse directly across the output of our 12V PSU ...

Much to his surprise - and mine, rather than blowing, as one might expect, it imitated a festoon bulb, glowing a cheerful orange ...

Which is because its resistance was so high that not enough current would flow to give a quick blow. 

 Oh thank you so much for explaining that to me, Jeffrey! I would probably have gone to my grave without understanding what was going on if you hadn't taken the trouble to tell me ... 

[ppppenguin]

Terry, I didn't do that explanation for your benefit:-)

it is possible that there are folk reading this thread who aren't as experienced as us two old b*****s. I minimise potee we could have left it as a puzzle to see if anyone else proffered an answer.

Anyway I'll be home tomorrow and be in a better position to look up fuse characteristics. Possibly even do some practical tests. May do them at reduced voltage to minimise possible harm. One of those small toroids I offered here a while ago may be unwillingly pressed for the purpose.

[boater sam]

It has often been said that the plug fuse is to protect the mains lead. So unless it is connected with tinsel 1A would seem pointless.
However I still prefer to use 1A fuses.
They are available from every electrical wholesaler I have dealt with.

[Old Sparky]

Reading the above, I've akways understood that the plug fuse is there to protect the mains lead, rather that the appliance to which itt's connected. Even so, I have just fitted a 1A fuse in the mains plug of an EAR 'Music Maker' ,Record Player, having fitted a new two-core mains lead made from 3 Amp Cable. My reason for so doing was because, like most British made equipment of those days, no internal fuse is incorporated. No doubt I could have (?Should have?) fitted one when repairing the Player, since an internal 1A, or maybe even 500mA QB Fuse would fail more quickly in the event of a fault condition than the plug fuse, whatever, within reason, it's rating.