Master Switch question

[Robert Suda]

Greetings All,I'm Robert Suda,
My boat (Emily Jane) is a 1975 Irwin 28 with a 1965 (rebuilt) engine.
The master switch is fine but available now are "make before break" type
switches. In the opinion of the more electronically savvy would I be
prudent to upgrade to a "MBB"? I assume it would safe-
guard the alternator in the event of a switch change from ALL to 1 or 2,
while the engine is running. Or should I just run in ALL constantly and
change to the house battery after the engine is stopped? (Perhaps I'm
over thinking a non-existent problem?)

[ndutton]

Robert Suda, welcome. I'm not sure why your thread is closed but maybe we can pick it up here.

You said:

Master Switch question
Greetings All,I'm Robert Suda,
My boat (Emily Jane) is a 1975 Irwin 28 with a 1965 (rebuilt) engine.
The master switch is fine but available now are "make before break" type
switches. In the opinion of the more electronically savvy would I be
prudent to upgrade to a "MBB"? I assume it would safe-
guard the alternator in the event of a switch change from ALL to 1 or 2,
while the engine is running. Or should I just run in ALL constantly and
change to the house battery after the engine is stopped? (Perhaps I'm
over thinking a non-existent problem?)

There's a strong likelihood your existing switch is already a make before break switch. It's easily tested with a multimeter preferably with the engine off just in case. I checked the specifications for the industry standard Perko 1/2/All switch currently designated #85XX but previously known as the 85A for over 40 years and it is make before break. I've never seen a battery switch that wasn't.