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ContinuousWave: Small Boat Electrical
DPDT Rocker Switch with Seven Terminals
|Author||Topic: DPDT Rocker Switch with Seven Terminals|
posted 02-20-2009 09:54 PM ET (US)
I have a DPDT Rocker Switch with [seven terminals] that I would like to use to control my bilge and aerator pumps. I would like the bilge to turn on when I press the upper position and the aerator pump to run when I press the lower portion of the switch.
I never worked with a seven-terminal DPDT switch and I'm a bit confused. I traced out the continuity of the switch (I think I got it right) see linked drawing.
What is the proper way to wire the switch? There are two individual lights on the switch. I'd like the light in the position that is depressed to light.
posted 02-21-2009 08:01 AM ET (US)
There is a discussion related to wiring of 7-pole switches located here - http://continuouswave.com/ubb/Forum6/HTML/000869.html
Generally, the two center terminals are the switch feed and the four outside terminals are the switch load connections. the 7th connection would be the switch lamps negative terminal.
If you are using a volt-ohm meter to ring out the switch, you will be reading continuity through the bulbs as well.
Connect your battery 12 volt positive feed to terminal 5 and jump it out to terminal 2. Connect terminal 7 to battery 12 volt negative.
Operate the switch and see if the bulbs are illuminating in the proper positions.
If so, you can wire the positive feed to the pumps on terminals 4 and 6 and the negative pump condutors to the battery negative common buss.
posted 02-21-2009 09:47 AM ET (US)
I don't think the linked discussion from the archives is particularly informative for this topic. Its discussion is in regard of multiple navigation lamps which operate in tandem in one setting of the switch, and separately in other settings.
It is hard to deduce exactly what is going on in your DPDT switch by your continuity measurements. There probably are some illuminating lamp resistances included in your measurements. The best way to discover how the switch is configured is to contact the manufacturer of the switch and get a diagram of it.
As for wiring the power distribution for the pumps, you only need a single-pole, double-throw, center-off switch for that. The battery power distribution branch circuit source wire will connect to the common terminal. The two pumps will be wired to the two terminals associated with that pole of the switch, one pump per terminal. One pump will operate when the switch is thrown up, and the other pump will operate when the switch is thrown down. When the switch is in the center position the circuit will be off.
When a switch has internal lamps to illuminate when it is operated, the lamps are typically internally wired is some fashion to the switch. I don't know of any universal convention of how this is done, so it isn't possible for me to advise you on how it is done with the switch you have on hand.
posted 02-21-2009 10:03 AM ET (US)
If you happen to have an illuminated rocker switch made by CARLING, you can discover its arrangement from the on-line documentation provided by CARLING on their website at
These illuminated rocker switches are made in a dozen or more configurations, and it would be highly speculative to deduce which particular one you might have on hand. Refer to their wiring diagrams for the particular switch you have.
Separating the lamp ground circuit to a seventh terminal does seem to be a common convention in these devices.
posted 02-21-2009 01:44 PM ET (US)
I found the following information on the switch: Carling, VJDA, 0715R, Mexico.
I went to the Carling site which has a lot of really good information but I couldn't find what I thought should apply to my switch.
My switch has seven (7) terminals positioned
Although there are diagrams showing 8 terminals I wasn't certain I could go by them i.e.,
I sent an email to Carling requesting wiring information for my application. To be honest, the way they are showing the layouts is a bit confusing to me.
I know I could have used a SPDT switch but I want to try to use what I already have. I understand the layout of the 6 terminal DPDT switch it's the #7 terminal that's confusing me.
posted 02-21-2009 02:35 PM ET (US)
Bella con23 my inclination was to do exactly what you indicate however it looks like that may result in both indicator lights being ON.
If that is the correct setup I'm wondering if the light is mechanically 'shielded' by the position of the rocker so it only APPEARS that one light is on. This really doesn't sound logical to me.
posted 02-21-2009 02:48 PM ET (US)
The indicator bulbs in the switch are wired internally on the positive side. What terminal 7 does connected to a battery negative is complete the circuit for the bulbs.
As you change position of the switch, the corresponding bulb will light electrically providing the negative wire is on #7.
From what I read of your posts you understand the concept, your just reading into the indicator circuit to deeply.
posted 02-21-2009 03:27 PM ET (US)
To be honest, the Carling switch diagrams and schematics confused me, too, and I have been involved in reading vendor catalogues and specifying electronic and electrical components for years.
posted 02-21-2009 05:26 PM ET (US)
Specifying switches can be tricky. There are so many options.
Here is the mother lode of Carling catalogues:
Consulting this catalogue:
I interpret as follows (see page 6)
V = the series of switches, i.e., the V-series
J = the contact arrangement; DPDT center off, with two indicator lamps; terminals 1-2-3 are one pole; terminals 4-5-6 are the second pole.
D = the switch rating; 20-amperes, 12-volts
A = termination: 0.250-inch quick disconnect, no barrier
as it has only the seventh terminal. Alternative is E/5, which swaps the indicator wiring.
Because there is a polarity shown, the indicators are probably LEDs. If you need to add a current limiting resistor you can by using terminal 7. The catalogue says the LED is already ballasted for up to 24-volts. This means you can just connect terminal 7 to battery negative.
posted 02-21-2009 05:58 PM ET (US)
A more complete part number might be something like
Which is a V series double-pole, double-throw, center off, 12-volt, 20-ampere switch with 0.25-inch QC terminals, sealed, illuminated, two lamps, #1 down and #2 down, red LED, flush black bracket, no seal, no actuator data specified, no legend.
posted 02-22-2009 01:43 AM ET (US)
I don't know where I saw it anymore but somehow I got the idea that it was incandescant rather than LED but I wouldn't bet one way or the other.
I'm going to wait until next week to see if I get any feedback from Carling. If I don't I'm going to do what Bella con23 suggested. I sense he is correct.
I'll post my success one way or the other.
posted 02-22-2009 02:01 AM ET (US)
Jim, D/4 & E/5 don't have the terminals numbered the same as mine as shown in my original link. They are a different layout also.
posted 02-22-2009 03:34 PM ET (US)
I think you are confusing the schematic diagram with a layout or pictorial. The schematic diagram shows the terminal numbers in an arrangement that may not reflect their physical arrangement on the actual switch.
In any case, you have my best advice. If you find out contrary information when you speak with CARLING, please let us know so that it can be made clear to our readers.
|Casco Bay Outrage||
posted 02-22-2009 09:45 PM ET (US)
My apologies if this derails the thread but I have an alternative.
In looking at your gauge panel, starboard side, I note you have room for another rocker switch. Why not have a separate switch for each pump? Just relocate the bus bar screwed into the plate to make room.
Just trying to adhere to the keep-it-simple-stupid (KISS) philosophy.
posted 02-23-2009 05:14 PM ET (US)
I haven't heard from Carling yet but I got impatient and wired it up. See sketch in original post.
Bilge Pump to Terminal 1
Bella con23 this is essentialy what you suggested only I moved the loads to different terminals because of the wire congestion between switches. Not knowing the interal circuitry is what was confusing me. You're right, I was just getting into it too deeply.
Everything works AOK.
Thanks for all the suggestions.
posted 02-23-2009 06:54 PM ET (US)
Atta boy Ron!
Jim is correct in his assessment of switches in general. There are literally every configuration of switches you can think of. Working in the healthcare industry for the last 35 years I would be foolish to assume the replacement device of a piece of equipment was generic by any means.
Experience has shown me that most switching for automotive or marine are generally wired alike. When in doubt I make good use of a volt-ohm meter or a standard lantern battery, a lightbulb and a couple of test clips.
That practice is result of not having growing up with the Internet at my finger tips. Something I couldn't fathom today.
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