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post #1 of (permalink) Old 11-11-2002, 12:15 PM Thread Starter
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Master Switch Question

Ok, I`m going to be installing about 5-6 switches for rock lights, driving lights, and backup lights..

The switches are going right in front of my tuffy center console on a custom made switch box...

My question is...

I want to install a MASTER SWITCH inside the tuffy box so that no one can play with my switches unless I have the master switch on..

I plan on running the ground/negative to the tuffy console, and hooking the switch up to that so nothing works unless it is 'on'.. I am wondering if my 35amp switch can handle like 5 or 6 negatives from the lights or if there is a better way to do this.. ??

I also want to install a kill switch inside the box to... any insite or sites where I can learn to do this???
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post #2 of (permalink) Old 11-11-2002, 12:32 PM
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Re: Master Switch Question

1. ALL the rocker switches should control a relay, which in turn controls the device to be switched on and off.
2. The Master swtich should control a Relay which provides voltage to the relays in #1 abvove.
3. ALWAYS control with RELAYS.
4. ALWAYS use a little current in the cab to control a bigger current outside the cab.
5. Use the kill switch to enable/disble the relay voltages in # one above and skip an master switch.
6. Figure out what you want.
7. Do a search ":Kill Switche"
8. Let us help...



Last edited by LEVE; 03-24-2009 at 07:45 PM.
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post #3 of (permalink) Old 11-11-2002, 02:09 PM Thread Starter
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Re: Master Switch Question

Thanks I got the kill switch idea going and am working on a fuel pump, and starter killer switch..

My question is why do I need to use a Relay if my switch can handle the amps required??

-Todd
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post #4 of (permalink) Old 11-11-2002, 03:14 PM
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Re: Master Switch Question

1. A HUGE switch may be able to handle the current.
2. You have to have that switch's wiring into and out of the cab.
3. These wires have to carry all the current.
4. If one of the wires shorts.... the ciruit's toast.
5. It's:
a. Safer not to run high current wiring into/out of the cab.
b. It's a cleaner circuit.
c. It's easeir to lay out.
d. Using all the same relays means you have parts if one relay fails.
e. The relays are cheap and standard.
6. Take at look at the attached schematic:

There is only a need for seven (7) wires to come into the cab and into the console. This lets you put all the relays, fuses, etc. in a convient and centeral area under the hood. It's easier accessed an MUCH safer.

The MASTER swtich in the schematic can also be used as the basis of the kill switch...

A kill switch should enable or disable electric devices by also eabling or disabling relays. [img]images/graemlins/grin.gif[/img]


Last edited by LEVE; 03-24-2009 at 07:45 PM.
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post #5 of (permalink) Old 11-11-2002, 03:19 PM
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Re: Master Switch Question

Running serious lights takes serious wire, besides a big switch. If you use relays, you can control them with small - 18 or 20-gauge wire, and 1-amp switches. It's a lot easier and cleaner to wire up. Then you can put maybe a 3-amp fuse to run all of the switches and relays. If a wire rubs through the fuse will blow quickly, and 3 amps can't do much damage.

If you wire the lights directly, it might take 12 or even 10 gauge wire, depending on the size of the lights. You could have 10 feet of wire between the battery and the lights, so it has to be big. The supply wire might take a 30-amp fuse. If that wire shorts out it can do some serious damage before the fuse blows. And the damage could be in the cab.

Lights, especially halogens, must have a good supply of power. The easiest way to get it to them is with a fuse or fusible link, heavy wire, and a relay. All of the high-current stuff is under the hood.
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post #6 of (permalink) Old 11-11-2002, 03:29 PM Thread Starter
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Re: Master Switch Question

Ok, I believe I understand the need for the relay. And will use one with High Powered lights such as Driving Lights like PIAA or HELLA or WARN lights.. but the $14 WallyWorld lights come with switch/wire/fuse all pre-done for the lights, I forget the actual amps but I know it's very few, and I`m also replacing the switch with a much heavier duty one..

I think this is fine for the small lights but for ones with a lot of current draw I see the advantages of the relay and keeping the power outside with a fuse..

What do you think ?

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post #7 of (permalink) Old 11-11-2002, 04:15 PM
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Re: Master Switch Question

Well, there is a right way to do it. The lights should have Watts and voltage rating. Divide Watts by volts for current draw - amps.

With a digital multimeter, measure the resistance in the entire wire package that came with the lights. Multiply that by two, because everything will degrade with time.

Multiply the resistance by the current. That will be the voltage drop. Subtract it from 14 - what the system should have when running, and that will be the voltage at the lights. Check that against the specs and you will know whether it's sufficient.

OR . . .

Accept that Wally World isn't going to be generous with the copper. What they provide will work, but probably not run the lights at their full capacity. And if they're halogen, they won't last as long as they should.

I use cheap lights, because they are prone to breakage on the Jeep, but I run them with relays because, cheap or not, they will work better that way.
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