SPDT switch

[flyboyo2]

The tech at Blue Sea indicates I can wire my two baitwell pumps to a SPDT switch as the pumps will never be operated simultaneously.  I don't have the switch instructions as of yet because it is specifically made to fit a Blue Sea panel and must be ordered.  The question is how to wire two pumps to one switch with three connectors; what is connected to the center post.  The wiring diagrams on Google are confusing to a tyro electrician.

[BMAC1988]

Center pole is you're 12v "feed" or "hot" wire. The outside poles are you're respective "loads" or in you're case you're baitwell pumps

[Capt. Bob]

You didn't mention which Blue Sea switch but as BMAC stated above.

http://assets.bluesea.com/files/resources/pin_out_drawing/8208.jpg

[flyboyo2]

Thanks for the info, guys.  The panel is a Blue Sea 4378 8 switch and the switch is 4152 on-off-on..  Serveral google expanations referred to the center post as the "common" feed which I thought was ground,but hey, I'm the first to admit I don't know what I'm talking about.  That is the main reason this forum is so great, there are so many knowlegable people on here you can't go to far astray.

[RickK]

I think you've figured out that since a boat doesn't touch the ground ("earth" and sandbars, rock piles, etc don't count  ) it doesn't have a ground.
It does have a negative battery terminal from which everything else is referenced - hence a "common" point to reference.  Eventually, though the harness, there is a "common" connection to a zinc that touches water, when you're in the water.
You can mount "negative" terminal blocks around your boat, all connected back to a common point (batt neg) and they are all the same point - "common".  You can do the same with positive terminal blocks. 
Everything on your boat needs a positive and a common to operate, usually through an on/off switch with a fuse.
Don't forget the fuse on the main line to the positive blocks too, to cover what a short would draw.  Look at the Blue Seas drawing, they are usually good.

[flyboyo2]

Thanks RickK, semantics strike again.  I have the wiring routine down but then when I research a problem sometime the official terminology trips me up.  As in the open, close routine on a switch seems bass ackwards to me.

[flyboyo2]

  arrrgh. I installed a SPDT switch for my two pump baitwell setup with a 22ga connecting wire from each throw back to the small LED indicator light on the AS panel.  Big problem, in either position both pumps run and I think they do so through the small wires to the single indicator light. I'm going to type a bunch of words here that I don't know the meaning of... I think the pumps are wired in parallel and need to be wired in series.  Is this the problem and if so what do I do?  This is my last last electrical problem and I want to get the tank in and see if she swims.

[RickK]

Is it a 3 position switch? ON-OFF-ON - that's what it should be if you're trying to run two separate pumps, one at a time.
Pump#1 On - OFF - Pump#2 On.  So they are not in series or parallel, they are on their own circuit.

[flyboyo2]

Yes it is ON-OFF-ON but the little LED light on the boat panel is wired to both throws of the switch.  Could the power be making a complete circuit from ON to the LED and back to the other ON?

[RickK]

If you throw the switch to either position both pumps come on?  If so I would say that the wire is connecting 12 V to both.

[flyboyo2]

That's what I'm thinking. How can I wire the panel indicator LED to come on in both positions without turning on the other pump?

[RickK]

Usually you tie the LED in parallel with the pump, one LED for each pump - the LED has a resistor built in to limit current. Try this (just thinking out loud) - Tie the anode side to the other side of both pumps before they tie to Neg and tie the cathode to Neg. Might be too much current for the LED though.  Did the switch come with a wiring diagram? Did you try looking at the MFR's website for a diagram?

[Capt. Bob]

FB,

Couple of questions.....

Did you add the bulb or was it on the panel?

Are you sure it's an LED and not a "grain of wheat" incandescent bulb?

If you want to use the SPDT switch and one bulb, you will need to add a couple of diodes to limit current direction.

The diodes will allow the current to flow to the bulb from each throw but will block the back feed to the opposite pump. Install one each on the 22ga wires between the throw and the bulb. Faced in the proper direction, they will allow current to flow to the bulb but not back to the non use pump.

[flyboyo2]

BINGO!!! Capt Bob strikes again!  An incandescent light was originally on the panel and I replaced it with a LED. Will a Radio Shack diode suffice or do I need an overpriced pair from WM? Oh yeah, is a diode a diode or do I need a specialty model for the tiny wire; any other advice?

[Capt. Bob]

A RS purchased diode will suffice, assuming they carry the size you need.

5A should work fine but that LED draws a lot less so see what they have.

EZ reading.
http://www.instructables.com/id/How-To-Diodes/