I have just started a new HO layout and will use DCC for train control. I have a lift-up access that I want to wire with isolated track sections to prevent trains from falling with the lift-up in the up position. Because my DCC power supply is rated for 5 amps, do I need larger rated switches for that power, or can I use reed switches?
You should take time to look through all the forums.
Ask in the below DCC electronics forum.
For a lift-up I would simply have a brass screwhead settling onto a brass contact plate, no switch at all.
To kill approach sections, arrange for the lift-up to be powered with feeders at opposite ends for the two rails. The 'closer to the operating pit' rail to the right of the lift-up, powered from the left end of the lift-up, will be dead unless the lift-up is down. Likewise, when the lift-up is raised, power will not reach the 'farther' rail to the left of the lift-up since the feed is from the right end of the open gap. The rails on the raised lift-up will be one-live/one-dead, which one is which determined by the location of the hinge.
The 'dead when bridge is open' sections should be as long as the longest train you are likely to run. No less an expert than John Armstrong had an operator back a train into the abyss where the infamous 'Bentless Trestle' was eventually built. A stop section the length of the locomotive could put a live-load coal train on the floor, or in a heap against the raised lift-up.
As for switch capacity, it is much higher than rating if the switch is thrown when not carrying current. I have 3 amps passing through switches rated 300 milliamps - but they are set before I apply power. No spark, no damage. That said, reed switches are usually used to trigger relays, not feed power-hog vertical DC traction motors.
Chuck (Modeling Central Japan in September, 1964)
Great idea on feeding the 'dead' sections. Now I don't have to even worry about any switches. Thanks.