Just another way to accomplish the same result really.
When wired into the main panel often the switch is not momentary like the dedicated switch is. This means it can be left on. Interestingly Steve D'Antonio thinks this is the best way to have it. His point is that when the bilge pump is needed and the float is not working (jammed for example) there are much better things to do than keeping ones finger on a switch.
The argument can go both ways, and I don't disagree with SD on that point, but having replaced thousands of dollars in batteries due to non-momentary manual bilge switches I still generally prefer the momentary ones at least for nuisance pumps.. My argument is that your bilge pump system & float switch should ALWAYS be in good operational order so you would never have to sit there with your finger on the switch.
You could/should alternatively wire in an emergency pump, with much higher capacity, and this would get a non-momentary... The smaller pump would be the nuisance pump which always seems to be the one to destroy a 2k bank of batteries....:cussing: Last year alone I had to replace three house banks due to the
manual switch being left on. Two sailboats and one power boat. One bank had been dead for at least two weeks and was only three months old..... Many builders used always on manual switches. The only time I replace dead banks for momentary switches is when people use cheap bilge pump float switches (eg: Rule).... The days of the RELIABLE old mercury float switches are long gone....
An override of the momentary bilge switch can also be wired to a panel breaker marked EMERGENCY BILGE....