Headlamp connector melting

Hi there,
After spending a night green laning we have seemed to hit problems with our N reg discovery 1 3.9 v8 Auto. We were about half way down a green lane when we notice that the newly wired in 100w wipacs went out we carried on using dipped beam an got home fine. After checking the wipac wiring to make sure all was ok ( 2x 100w spots wired with a 20amp fused supply direct from the battery going into a 30 amp relay using a feed from the main beam circuit to switch the relay on/off). upon switching the lights on and finding that only the sidelights work we decided we must have blow a fuse which sure enough we had blown fuse no.4 so simply inserted another for it to pop as soon as I turned the lights on, investigating further it appears that both headelamp connectors have melted quite badly which was causing a short ( picccy available if wanted). Question is what is causing the headlamp connectors to melt like this, is it my spotlights or have I missed something?

Thought I should add this as it may help. Wiring diagram I used for the lights : 2x100w spot lights - Discovery Forum - LR4x4 - The Land Rover Forum Please note I have not yet installed the overide switch!

Common fault -

re-wire, re-place - do a search on here ...loads of threads

+1. The headlight connectors are sods for it. Keep 'em clean once new one are in place

Any oxidisation on the connector contacts and they offer some resistance, this then causes hot spots melting the plastic housing.
Contacts must also be of the right rating 100W/12V = 8.33Amps. Allow for some surge when first turned on.
Also make sure all connections are good especially earths

Thank you all for your help Have ordered two new connectors and will check the rest of the wiring as best as I can!