There are recognised Spill Hazard Zones within some (all?) aircraft. This was incorporated in standard practices after a certain incident as described above caused multiple systems failures. I think it was a B737.
If there is a significant water spillage in this zone then an inspection of the electrical equipment compartments is required before the next flight.
The electronic/electrical racks are protected by sealed floor panels, drains around the door thresholds (on some anyway) and drip trays above the racks. so long as the integrity of these protections is maintained then any spillage should cause no adverse effects.
And therein lies the problem. Maintenance is expensive, lack of maintenance more so.
Indeed I believe the SHZ isn't on all aircraft, never seen a Tech news briefing for the 747, I believe it's prominently aimed at the 737.
Indeed I thought (perhaps wrongly) that the SHZ was set up due to water leaking from gaps in the galley flooring. Requires a Tech log entry and inspection (If I remember correctly).
But to answer the question, I believe the risk of fire is greater from something within the E&E bay than from something external to it.