John Bryan wrote:

In message
Martin Brown wrote:

On 19/03/2018 16:15, Harry Bloomfield wrote:
whisky-dave pretended :
Which is the best fuse to use (3A, 5A or 13A) with a 1.15kW electric
fire at a potential difference of 240v

5amp ought to cover it, but it is very tight. If it fails find a 10amp.

It isn't *all* that tight in practice but the plug will run slightly
warm. A nominal 5A fuse will take nearly 20A to blow in the first second
and will probably support a current of 7A almost indefinitely. eg.

https://docs-emea.rs-online.com/webd...6b8002b71e.pdf

It would be much more challenging with a halogen light where there is a
significant inrush current when the filament is cold. An electric fire
is a relatively benign load with a decently high cold resistance.

Nominally 13A fuses will support boiling two 3kW kettles for long enough
to destroy the still coiled up extension cable they were plugged into.

This is due to induction heating not resistive heating by the load
supplied.

No it is due to resistive heating and poor heat dissipation by the
coiled lead.



All our village hall extension cables now have thermal overload
protection to save them from the church's tea ladies.


--

Roger Hayter