Sorry for the slow response Nelson, with everything else that's been happening recently I seem to have overlooked this post.
I suggest you use a 35 or 40Amp fuse to be on the safe side. If you decide to use the mini blade type, you would need to use a pair of fuse holders wired in parallel, each fitted with a 20Amp fuse to provide 40Amp capacity as shown in this diagram:
Fuses are pretty small, cheap, lightweight and guaranteed to blow if a short circuit fault occurs, so you could keep a few spares and carry them with you just in case.
Circuit breakers are much larger, heavier and more expensive too, but they do have the advantage of being quick and easy to reset after they have been tripped.
The majority of Miniature Circuit Breakers (MCB) are intended for mains AC voltages of up to 415V AC, but some manufacturers also give a voltage rating of 48V DC for the same item.
I have previously looked into the possibility of using a Mains MCB and was surprised to discover exactly how much current is required to activate them.
There are 3 MCB types, Type B, Type C and Type D, and the speed at which they trip depends upon the level of overload, and is usually determined by a thermal device within the MCB.
All 3 MCB types use a magnetic fault protection, which trips the MCB within one tenth of a second when the overload reaches a set level.
Type B trips between 3 and 5 time full load current;
Type C trips between 5 and 10 times full load current; and
Type D trips between 10 and 20 times full load current.
If you decided to use a circuit breaker, a 20Amp Domestic type B MCB would require 60 to 100Amps to trip it, and the 20Amp continuous rating should be ideal for a Magic Pie.
Click for more details.Alan
