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  Wiring gauges in series. OK ?

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Author Topic:   Wiring gauges in series. OK ?
bang4dabuck posted 07-30-2010 06:15 AM ET (US)   Profile for bang4dabuck   Send Email to bang4dabuck  
I am installing new gauges on 17' Whaler (Katama). The console is very open and kind of small. With the idea of trying to avoid a "ball of confusion", I was planning to wire them in SERIES. I am installing 2 Temp gauges, Tach, water pressure and an ammeter. I was going to jump the red, black and blue wires from one gauge to the other and from the last gauge (Tach) to the ignition switch. Will this create inaccurate readings or any other problems ?


Chuck Tribolet posted 07-30-2010 09:26 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
It sounds like you are proposing to wire them in parallel,
not series. Parallel is fine, that's how my Montauk was
wired at the factory.

You really going to have an ampmeter? That's a bit unusual
on a boat. And probably hard to wire given that the charging
current usually goes down the big cable, and you don't want
to route that through the ampmeter (way too much current
when cranking).


jimh posted 07-30-2010 04:57 PM ET (US)     Profile for jimh  Send Email to jimh     
It is not recommended to wire gauges in series. I doubt that any of them would work if their power leads were wired in a series arrangement. As Chuck as pointed out, your plan appears to wire the power, ground, and lighting circuit to the gauges in parallel, not series.

To distribute the power, ground, and the switched gauge illumination power to several gauges, it is a standard practice to wire a circuit from one gauge to another, as opposed to wiring all of the individual gauges with separate circuits to a central point where there was a positive distribution bus, a negative distribution bus, and a gauge illumination power bus. You could also use one of the gauge terminal posts as a common point and distribute the circuit from there.

bang4dabuck posted 07-30-2010 05:24 PM ET (US)     Profile for bang4dabuck  Send Email to bang4dabuck     
My bad. I meant in parallel.
jimh posted 07-30-2010 09:18 PM ET (US)     Profile for jimh  Send Email to jimh     
Series and parallel are not the right terms to describe the wiring method. Series and parallel are terms to describe the electrical circuit arrangement. To describe the physical wiring technique, I would use a term like daisy-chain to describe a wiring arrangement where the power, ground, and lighting circuits are carried from one gauge to the next in a string of connections.

As long as the current in the circuit is low, the wire conductor gauge is adequate, the total circuit length difference from first gauge to last in the string is short, and all the connections are well-made, it should not be a problem to string the circuit from gauge to gauge. In some cases the distance is only a matter of an inch or two.

L H G posted 08-02-2010 07:53 PM ET (US)     Profile for L H G    
I don't know what kind of engine you have, but with wanting to install two temp gauges, it sounds like an OMC V-4.

What you are doing doens't sound right to me, or at least it's overly complicated.

First of all, as mentioned, forget the ammeter. I have never seen one on an outboard, and the heavy gauge wiring work is not worth it. I was going to do these on some Merc outboards, and the factory consultant told me flat out not to do it! I still have two brand new Ammeter gauges siting in a box unused!

I would assume your ignition harness, or side mount control, has the leads, or a gauge pigtail, for gauges already there - purple for Ignition (+), black for negative (-) and a grey wire for tach sender, and a tan wire for temp sender (if the engine has one). I would install these leads to the tach first, and from there use same color wires to jump to the ignition and neg terminals on the temp gauge and volt gauge, ending up with the blade connectors to the water pressure light, the only power it needs.

I would not bother with a separate switch for the gauge lighting. Instead, wire so the lights go on automatically whenever the engine ignition is turned to "ON". This is easily accomplished with a short jumper wire from the ignition terminal on EACH gauge, to the light terminal on each gauge. You will never have a bulb burn out, and the heat generated will help keep the gauge fog free, and clear out any condensation that may get in, and have a lot less wiring too.

Finally, I don't see the need for TWO temp gauges on a small V-4 engine. Sounds like overkill to me. Simply attach the gauge to the sender on the higher of top cylinders. Instead of two temp gauges, I would install a a volt gauge, an hour meter or both.

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