What is this 'Service On' Switch?

[britinusa]

It's really really difficult to get a good view of the wiring behind this switch. I have no clew what it's for. ( Red arrow points to it )
1987 C34 Mk 1 Tall Rig fin Keel.

[scgunner]

Looks like a PO thing to me that's obviously a replacement electrical panel. Before I started digging around behind the panel I'd flip that switch on then turn everything on then flip it off and see what happens.

[waughoo]

It is slightly possible that used to be a light.  On my panel there is a "service on" light that will be on when there is power to the panel.  Mine is burnt out so it no longer works, but a PO (as suggested) may have used that spot in the panel to install a switch instead.

[britinusa]

Looks like a PO thing to me that's obviously a replacement electrical panel. Before I started digging around behind the panel I'd flip that switch on then turn everything on then flip it off and see what happens.

Did that, nothing!
I'm planning on a complete panel replacement. The area currently consists of 3 different pieces looks horrible and the nightmare behind them is cause for more. Long term project.