Wow. Way over my head, but the message is clear. Guess I need a contactor/coil. Could you provide a link to a suitable option and draw me a simple wire diagram? Would be very much appreciated. Rather buy more now than pay more later....I'm not an electrical engineer, just a lowly physicist/chemist, but there's a lot of bad advice being thrown around in this thread. I'm no safety nazi either, but you really need to change your design.
Apply nodal analysis to the nearest junction before the switch-element loop. You will see that the switch as a whole will actually see 45.8A. This follows from Kirchhoff's circuit laws. Each leg will have to carry the full loop current, and since there's two legs you get a big number. That's semantics, though.
What really does matter is not current or voltage, but the amount of power dissipation that the contacts on the switch can handle. When the switch is in the closed state it has some small internal resistance, much like wiring. This resistance causes heating based on power (energy per unit time) pushed through it. Depending on the design and materials there is a certain amount of heat (energy) that can move out of the contacts in a given amount of time (flux). If the amount of heat generated is too large the device melts, catches on fire, or otherwise breaks down. This is why it is generally considered bad, and usually against code, to run NMB inside conduit. The additional layers impede heat flow away from the wires. So that's why the switch is derated with respect to current at higher voltages, it generated too much heat.
That switch is not rated to handle the amount of power you are pushing through it. You should upgrade or use that switch to control a DPST contactor. When choosing a replacement switch or contactor for your application you need to find one that has a contact rating of at least 26 A at 240 V. Your current switch may be working fine for now because there's always a safety factor in those ratings, but it could also be on the verge of failure. If you want to keep it just add a 30 A 240V contactor with a 120 V coil. Disconnect all the legs from your switch and run them through the contactor. Run one hot leg from your hot buss through the switch, then to the contactor's coil. Run a neutral from your neutral bus to the other side of your contactor and you're set. It you want to you can also install a small inline fuse on the hot leg which will allow you to run smaller wire after the fuse.