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Author Topic:   choosing the correct type of switch
djreichenbach posted 06-19-2007 10:22 PM ET (US)   Profile for djreichenbach   Send Email to djreichenbach  
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)     Profile for Over the LINE  Send Email to Over the LINE     
This is the article on nav lights.

djreichenbach posted 06-19-2007 11:50 PM ET (US)     Profile for djreichenbach  Send Email to djreichenbach     
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.
Chuck Tribolet posted 06-19-2007 11:54 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
"Poles" is how many independent sets of contacts are there.

"Throws" is how many positions the switch has, but don't
count the "everything off" position, IF it has one.

Your standard house light switch is a "single-pole" "single-throw"
(SPST) switch.

The "everything off" postion is assumed to be be there for
single-throw switches, and assumed to NOT be there for
double-throw and up switches.

DPDT = double-pole double-throw
DBST = double-pole single-throw

for nav lights, you need a DPDT switch with some all-off
position. My '97ish Montauk uses a DPDT center-off switch.


Whale1 posted 06-20-2007 09:57 AM ET (US)     Profile for Whale1    

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)     Profile for Over the LINE  Send Email to Over the LINE     
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.
djreichenbach posted 06-20-2007 03:07 PM ET (US)     Profile for djreichenbach  Send Email to djreichenbach     
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.


Chuck Tribolet posted 06-20-2007 09:44 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
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.
djreichenbach posted 06-20-2007 10:26 PM ET (US)     Profile for djreichenbach  Send Email to djreichenbach     
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.


towboater posted 06-21-2007 12:32 PM ET (US)     Profile for towboater  Send Email to towboater     
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.
Side, & white mast are all required at the same time to run at night...second pull activates the side lights IF you are running a all round mast or stern light.
The 3 pole switch would be OFF/ON/ON.

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 is dark.


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