Drove 15 miles this morning stopped three times car started fine.Left for 3 hours went to start completely flat  central locking not working no dash lights nothing. Is there a main fuse anywhere thanks

check if there is a drain on the electrics, a dash cam or something recently added, what does it look like when you try starting

Main fuses as far as I know are in engine compartment in front of battery although there may be a master fuse elswhere. I would put a meter across battery to check its still charged if you suspect fuses. It could very well be the battery itself. Sons was fine in the morning drove around town and started stopped a few times but when he came back it was totaly dead. Battery had failed and obviously wasn't taking charge although no battery light on. Got a new battery and its been fine since. AA were called out and the guy reckond a cell or perhaps two had failed. 

A fuse or a faulty fuse will not cause a battery discharge.

 

To the OP, why are you asking about a "main fuse"?

In my experience  it is likely to be a battery fault. When mine wouldn't start I called the AA and he restarted the engine using another battery connect in parallel with my battery. He left it running like that (to recharge my battery) for about 5-10 minutes. As soon he took off the first lead between his battery and mine, the engine stopped. My battery had developed an internal fault; high resistance, almost open circuit.

The way the fuses are connected is that the first fuses are high current fuses that look like vertical strips of metal mounted near the battery and connect to it. Power from these then go to lower current fuses and relays which in turn feed the even smaller fuses such as those at the end of the dashboard.

The fusing philosophy is standard whether it is a house, car or airplane. The fuse size is chosen to protect the cable connected to it in order to prevent fires from cable burn out. The cable is sized to carry the maximum current in that circuit.

I have seen car enthusiasts connect lights or sound amplifiers directly to a battery with no fuse! I guess some will have found out the hard way with a car fire on the hard shoulder.

 

If you use lithium batteries at home (especially LiFePo pouch type) you MUST have the appropriate fuse in circuit as once their maximum current has been exceeded, the cells become hot and get into a runaway condition. The chemistry of these cells provides all the oxygen needed to keep the cells burning at high temperature. They can also catch fire if you use the wrong type of charger even if the voltage rating is the same: this problem has been seen on electric scooters.

If any help, I had exactly the same symptoms yesterday - after having removed the battery.

19 hours ago, redpied said:

Drove 15 miles this morning stopped three times car started fine.Left for 3 hours went to start completely flat  central locking not working no dash lights nothing. Is there a main fuse anywhere thanks

If any help, I had exactly the same symptoms yesterday - after having removed the battery.