Put a box somewhere with a toggle switch or a gauge on it. Depending on where it is maybe some wires. Put a label on it. Who's going to waste time dismantling your system to see if that's really a fuse box or a water pump switch? Or, make a trash basket or hamper with a fake bottom. Or, install something that looks like a water filter under your sink , but is not hooked to the plumbing. Or have a false backing in the medicine cabinet or above a drawer. Or,, have an old style tape recorder case with the guts removed (you can't even give those old tape recorders way.) Or, create a false wall or ceiling or floor panel. Or, a false backing in the glove compartment. Or, an envelope inside the zippered cover for a pillow or a mattress. Or, a hidden panel under the shower or the toilet base. Or, where I put mine, which I'm not telling.