Fuses

[GeoffK]

Hi
What should be the rating of the fuses in the fuse box? I currently have 35amp fuses in the top 3 locations and a 10amp in the bottom, with a 35amp in the line fuseholder under the fuse box. The workshop manual that I have is no help. The 10amp fuse had blown which might have been something to do with the recent horn problem that I had. (New horn pencil arrived today and working fine having swapped another fuse for testing purposes) Cheers Geoff

[Paul Scott]

They are all the same 17amp 35amp blow

GFS3035 is the part no.

Check your private messages Geoff, I sent you one last week. It does not look like you have read it yet.

Paul

[Michael Barclay]

Hi Geoff
The factory rating for the fuses are 17 and 35 amp. The bottom fuse position protects circuits that operates independent of the ignition switch. This includes the horns, interior light, and cigarette lighter. This should be 35 amp. The 10 amp fuse you currently have fitted will blow every time you operate the horns.
From the top down the fuses in the fuse box should be as follows
Position 1: 17amp. Protects right hand side and tail lights
Position 2: 17 Amp. Protects Left hand side and tail lights
Position 3: 35 Amp Protects circuits which operate only when the ignition is switched on. (Indicators, stop lamps, reversing lamps)
Position 4: 35 Amp. Protects circuits which operate independent of the ignition switch. (Horns, interior light, cigarette lighter)
The fuse in the inline fuse holder below the fuse box should be 35 amp.
Hope this helps
Mike Barclay

[Allan T]

After describing the functions of the four fuses in the fuse box, my 1978 Driver's Handbook goes on to say on page 46: 'Spare Fuses - Two spare fuses are provided and it is important to use the correct replacement fuse. The fusing value, 17 amp continuous (35 amp blow rated), is marked on a coloured piece of paper inside the glass tube of the fuse'.

In his 'MGB Electrical Systems', Rick Astley says on p43 'All the fuses in the fuse block are rated at 17A carry current'.

[Bumpa]

I have always considered all four fuses to be the same, 17 amp continuous with 35 amp blow. To have a fuse with 35 amp continuous rating would be overkill, and on MGB circuits could lead to wire melt before the fuse blew.

[Michael Barclay]

Hi Guys
No excuses, think I need to pay a visit to that well know high street opticians. I only gave the fuses a cursory look when looking in the fuse box and saw 17amp and 35 amp. You are all correct and after taking a closer look can confirm all the fuses are the same value and rated 17 amp continuous and 35 amp blow (See picture)
Apologies for posting misleading information.
Mike Barclay

[Paul Scott]

I'm going to John Lewis for my eye test next weekend.

It's only £25 and is £22 cheaper than the opticians my wife works for