Now, here's a project I've been nibbling at for far too long... but now it's "job done".
Headlight and Fog Light relays.
I wish I was better at wiring. The connections are correct, and I'm getting a lot better at labeling things (heat shrink labels are very helpful), but I want to get "neater" at actually stringing the wires. Patience helps.
That said:
All wires/connectors are marine grade "Ancor" tinned stranded wire. Bus blocks are from Blue Sea Systems. I found a relay box on Amazon, I don't remember the company, but it's listed (and seems to be) waterproof.
I ran a 10 gauge wire to a bus block in the engine bay, accessible under the faux intake opposite the heater intake. My Defender is RHD, so it's on the right side. Next to the bus bar, I mounted the relay box, which holds six relays and six fuses. For the fog lights, I installed a new switch on the steering column (RN part number: PLE498). This switch is actually supposed to be for the rear fogs, but I have that next to the hazard and rear defogger switch, so I went with this one. Each lamp has its own relay. Spaces 1 and 2 are the fogs, 3 is the dipped beam on the starboard side, 4 is the main beam on that side, 5 is dipped on the port side, and 6 is main on that side.
Fogs were simple: 10 gauge to the bus bar, to the relay, and to the lights. 16 gauge wire to/from the switch, because that's what I had. 90 watt bulbs in the fogs.
For the headlights, I ran 18 gauge wires from the original wiring to the relay box. When the stock switch goes on, it closes the relay. The bus bar powers the relay, and then I ran 10 gauge wire to the lights. H4 lamps were replaced with 100 watt main beam, 55 watt dipped beam.
I need to check my alternator to be sure: the data plate is "underneath", so I need a mirror, but I believe it's a 120 amp alternator. If not, I'll have to upgrade that.
Now I'm just waiting for it to get dark so I can check how they look. Only down side is I'm north of 46 degrees north latitude, so I'll need to stay up past my bed time to do that!