Main fuse blowing

[peterengland]

My main fuse blows every month or so but only when I have started the bike and am wheeling it out of the garage, never on the road. Why could this be I wonder?
The fuse is the second from the right in the carrier of five, always this one.

[mike the bike]

Make sure the fuse contacts are clean and tight.   A bad contact will get hot and may cause the fuse to die.  Seen it loads of times.

[peterengland]

Yes that was my first thought, I cleaned them about 6 months ago but apparently didn't seem to help, still can't work out why it never happens when I'm riding it. (CB550)

[BigAl (Alan)]

Has the harness/fuse carrier been modified in the past. The wiring diagram for the CB550K & CB550F shows 3 fuses.
You mentioned 5 fuses, I gather the 2 other fuses are spares?

[mike the bike]

Try waggling the loom to see if the insulation has chafed on the frame or battery box.  When you're wheeling it, you're more likely to turn the handlebars more sharply then when you're riding it.  Have a look where the loom goes into the headlamp.

[peterengland]

only the 3 middle fuses are working, the outer 2 are spares

[BigAl (Alan)]

If the main fuse is blowing on initial start-up, I would take a look at the 6-way connector at the key switch end.
Signs of overheating as image maybe the cause?

[peterengland]

it's not on initial start up, just when wheeling it when the engine is running

[BigAl (Alan)]

The electrical short could be in a number of places, key switch being the first item to check
Is the wiring harness & connectors in good condition?