Advise needed on light issue.

Hi guys. I could use some advise on a light issue.

I installed all new wiring and and new light switch 5-6 years ago and put in modern h4 halogen bulps. Ive had zero issues up until a couple of days ago. I Came home and noticeced my low been headlights was flickering on and off.

I turned the lights off and back on tha flickering started again. I then let it sit for the Night and next day i tjekked all connections and Found nothing Wrong. I turned the lights on and let it sit, and all was functioning normal with no flickering. I had no problems since then but noticed the wiring on the light switch was pretty hot.

Ive been told that i need to wire in a relay and the light switch has some kind of internal overload fuse and therefore the lights was flickering cause the switch was overloaded?

I was just wondering why it has not had any problems before now and if i need to be Aware of something Else going on? Or i just should vire in a relay and Think nothing more of it. Also i should mention that here in Copenhagen it is a law that you need to run your lights on at all times even during the day.

I have checked all connections and grounds without any visible issues. And all lights work fine. Only experienced the flickering this one afternon, have never had the problems before. I considered to put in led bulps. But they are not legal to run on the public roads.
Any advise or thoughts are on this is welcome. Thank you in advance Henrik.

Oh forgot to mention that it was a pretty hot day, and she had been sitting in the Sun for a whole day and was pretty toasty inside. If that could have something to say. Thanks again.

I have installed relays in my cars to control the lights. now only the control for the lights passes through the light switch and the switch cannot overheat.
Something like this, https://www.summitracing.com/parts/rfw-hr58

So it is true that there is a overheat protection build in to the switch ? But i still wonder why the problem starts now after years of running this setup without problems.
Can a lightswitch become : worn: so it has problems from years of service?
Im going to wire the relay in regardless, just wondering why i first need it now.

Finn is right.
According to Ohm's law, voltage equals current times resistance, or V=IR. Resistance is falsely assumed to be constant when it's actually not. It changes depending on temperature. The higher the temperature, the higher the resistance. Current flowing through a circuit generates heat because of resistance. The greater the current, the more heat gets generated. The calculations for current demand, load, etc., done by automotive engineers are "adjusted" by executives to result in "good enough to work for a few years" and reduce costs so as to increase profits. As a fun exercise, think about how many feet of wire are used in one car. Next, imagine if by going just one size (gauge) smaller, you could save (for the sake of argument) one-cent per foot. Now imagine that savings over your entire production run. All circuits are just barely on this side of the edge of working satisfactorily to meet safety standards, not all foreseeable real world conditions such as upgrading to more powerful headlights.
Any time you add something to a circuit that draws more current than originally equipped, that circuit will get warmer than before, the wire insulation will harden shrink and crack, and the connector terminals will get hot enough to distort and melt the plastic terminal holders.
Installing a power relay system like Finn mentioned is a good solution. I did that years ago, and, I drive my Monte Carlo with the lights on every day with no problems. Plus, I just recently upgraded to LED H4 bulbs; way clearer and brighter than halogen bulbs. I also upgraded the original 10SI alternator to a 12SI and the charging wire from the alternator was upgraded from 10ga to 8ga.
One last thing; I strongly recommend redundant grounding. Add some more ground straps and "check" grounds by actually disconnecting them, cleaning the grounding surface and strap terminals with steel wool, then reassembling.

Ok so i guess i will ad a relay and be happy. Its not a Big job so it wont take long. I have already checked my grounds and added one more. I made a large Ground wire from the back of the head to the firewall. I already have one from the battery to the fender and from the battery to the engine and one from the battery to the frame. So i hope i am covered.

Thank you for your always swift and helpfull replays. Im happy i can always turn to you guys and learn new things. I have Found that by learning to do it myself. I save myself alot of trouble not having others that claim to know what they are doing work on my car.

I have Wired in a relay and it seems to work as intended. Now the wires dont seem to get as hot. So im hoping it has fixed the issue. I have not had any flickering as of today.