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ContinuousWave: Small Boat Electrical
choosing the correct type of switch
|Author||Topic: choosing the correct type of switch|
posted 06-19-2007 10:22 PM ET (US)
I am replacing the push-pull 3 position switch for my nav. lights on a 1975 Montauk. Can someone tell me what the terms "pole" and "throw" refer to and when you use single pole-single throw, single pole-double throw, DPDT,DPST switches?
I am looking at the cole-hersee M-531 and M-532 and am trying to figure out which switch is right for activating the stern light(anchor) circuit with the first pull and then both the bow/stern light together(running lights) with the switch pulled all the way out.
I am also replacing the trim buttons with a rocker switch that is monentarily on when pushed up or down and normally off. Cole-hersee has two such rocker switches. One is SPDT, the other is DPDT. I don't know which one is right for this application. Any help would be great.
|Over the LINE||
posted 06-19-2007 11:41 PM ET (US)
This is the article on nav lights.
posted 06-19-2007 11:50 PM ET (US)
Thanks. I a read through this before and it still didn't really answer my question about the different switches. It seems to me that the cole-hersee m-532 is for 3 circuits, not 2. Makes more sense to me that for my wiring scheme (2 circuits), the M-531 would be the correct choice.
posted 06-19-2007 11:54 PM ET (US)
"Poles" is how many independent sets of contacts are there.
"Throws" is how many positions the switch has, but don't
Your standard house light switch is a "single-pole" "single-throw"
The "everything off" postion is assumed to be be there for
DPDT = double-pole double-throw
for nav lights, you need a DPDT switch with some all-off
posted 06-20-2007 09:57 AM ET (US)
I used the 531 when I rewired my nav lights. 1st click pulled = anchor light. 2nd click pulled = anchor and nav lights. pushed all the way in = all off.
I Googled the 532 and it seems that it is for additional circuits like cabin lights, etc.
|Over the LINE||
posted 06-20-2007 10:08 AM ET (US)
If you use the M-532 switch, leave the un-needed contact empty. I think it wires as follws: #1 is the "all around" and #3 is the bow light, #2 is left empty.
posted 06-20-2007 03:07 PM ET (US)
Thanks for the explanation. Makes sense. I'm going with the c.h. m-531 for my nav. lights. Based on Chuck's description, it sounds like I need a DPDT rocker switch (up position momentarily on, center is off, down is mom. on)for my trim. The existing two button switch has four wires coming in so I assume I need two sets of poles (DP).
It makes things interesting when you are replacing electrical equipment that is around 30 yrs. old. The good news is, I don't think I can electrocute myself with 12 volt DC power.
posted 06-20-2007 09:44 PM ET (US)
What motor is the TT switch for? IIRC, My Evenrude uses an SPDT, but
there's a relay back at the motor. The typical reversing DC
motor does use a DPDT center-off switch.
posted 06-20-2007 10:26 PM ET (US)
I have a 90 hp. 1989 Merc. There are two purple leads spliced together, one going to each pole, a light blue at one pole and a light green wire at the other.
The "trailer" mode/button (purple wire) to trim the engine way up has been eliminated. I just use up and down for everything, center position, normally off.
posted 06-21-2007 12:32 PM ET (US)
Whale 1 has it right...depending if you are running a all round white mast light or mast and stern lights that project fwd & aft.
Anchor light is all round white, first pull.
If you are running mast and stern lights that project fwd & aft, the ANCHOR light needs to go OFF when you activate the second pole. OFF/ON-OFF/ON
I recommend each light should have its own fuse to make diagnosing whether a fuse, short or bulb is the problem a lot quicker down the road. Usually you wont know if you have a problem until...it is dark.
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