OldIHC

Will the group please illuminate me on spotlights (see what I did there...) for my KB3:
1) What is the difference in Unity S5 (on truck now), and S6 spot lights?
(Is it bulb size?)
2) Can I use the original S5 and change to a 12 volt bulb with the upgraded 12 volt system?
Wiring precautions???

Seasons best to all !
Hector

I am pretty sure the S5 uses a PAR 36 lamp and the S6 a PAR 46. The PAR number is 1/8th's of an inch, as in 36/8 and 46/8. Lamps are available in both 6 and 12 volt versions directly from Unity and from many other online retailers:

http://www.unityusa.com/Bulbs-Lamps-_c_1.html

So would my original 6 volt S5 accept and be electrically happy with a 12 volt lamp? as well as wiring? Thanks, Hector

Yes, it should be as simple as swapping the lamp for a new one. They have the same physical dimensions whether rated at 6V or 12V. The old wiring is fine assuming it is in good condition to start with. For a given wattage, a 12V lamp will use half the current of a 6v lamp.

Just for fun, these are the most basic and useful equations in all of electrical engineering:

- Ohm's Law: V=I*R, where V is volts, I is current (amps) and R is resistance (ohms).
- The Power Law: P=I*V, where P is power (watts), I is current (amps) and V is volts

The second is based on the first, and there are other ways to express them by re-arranging the terms. The most useful of these is P=I*I*R, and this describes what happens to the power dissipated by the wire itself.

The wire has some natural amount of resistance, which is why wire gets hot if too much current is run through it. But the interesting thing is that it dissipates power (heat) exponentially as the current is increased. The opposite is also true. When the current is reduced, the power dissipated by the wire drops exponentially. This is true even when the total power delivered to the load (like the lamp, for instance) remains the same. This means that 12V systems can use thinner wire than 6V systems, all else being equal. Or, in your case, the 12V lamp will be perfectly happy using the wire that was already used for the 6V system.

Really great information answering my questions. Love the EE formulas -- now if I only had the context to understand them -- so I developed my own formula: (with apologies to Georg Simon Ohm)

- OMG's Law: V=I*R, where V is "Vatt?", I is I (Don't Have A Clue) and R is reasons (I love this groups knowledge)

I think I'm ready to move forward.

Thanks !
Hector