What Master Disconnect Switch??

Posted By: mopowers

What Master Disconnect Switch?? - 06/30/09 03:32 PM

I need to buy a disconnect switch. Which one do you folks recommend?

I've noticed there are a ton of choices on Summit's website. How many amps does it need to be? They have them from 20 all the way to 300.

Posted By: 540CUDA

Re: What Master Disconnect Switch?? - 06/30/09 03:43 PM

Look at Ron Francis wiring, sorry I dont have the link. They make a 4 post switch for use with an alternator. Im not sure of the amperage rating though.

Posted By: mopowers

Re: What Master Disconnect Switch?? - 06/30/09 03:49 PM

Do I need one with 4 posts, do will a 2 post switch like this one from Flaming River work?

Posted By: MoparforLife

Re: What Master Disconnect Switch?? - 06/30/09 04:08 PM

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Do I need one with 4 posts, do will a 2 post switch like this one from Flaming River work?

Sure it will. Many 2 post switches are used. Probably more than any other. Mine is a master cut off switch off a retired school bus.

Posted By: Blucuda413

Re: What Master Disconnect Switch?? - 06/30/09 04:17 PM

I like the flaming river with the red knob. You twist it to turn it on and push it to turn it off.

Posted By: mopowers

Re: What Master Disconnect Switch?? - 06/30/09 04:51 PM

Thanks a lot for the help guys! I've never installed one of these switches before.

If I get a 2 post switch, I will need a continuous duty relay for the alternator lead right? Wouldn't it be better just to get a switch with 4 posts so the relay won't be needed?

Posted By: RobX4406

Re: What Master Disconnect Switch?? - 06/30/09 05:53 PM

Quote:

Thanks a lot for the help guys! I've never installed one of these switches before.

If I get a 2 post switch, I will need a continuous duty relay for the alternator lead right? Wouldn't it be better just to get a switch with 4 posts so the relay won't be needed?

I like the FR switch and a S605 relay for the alt wire. You can always jumper around the relay if it fails. You're no different at that point than the guys that run the alt wire straight to the battery if it fails. I've not had a S605 fail yet, but carried a jumper wire just in case.

Posted By: mopowers

Re: What Master Disconnect Switch?? - 06/30/09 06:15 PM

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Thanks a lot for the help guys! I've never installed one of these switches before.

If I get a 2 post switch, I will need a continuous duty relay for the alternator lead right? Wouldn't it be better just to get a switch with 4 posts so the relay won't be needed?

I like the FR switch and a S605 relay for the alt wire. You can always jumper around the relay if it fails. You're no different at that point than the guys that run the alt wire straight to the battery if it fails. I've not had a S605 fail yet, but carried a jumper wire just in case.

Thanks Rob. Is there an advantage to doing it that way versus just using a 4 post switch? It seems that using a 4 post switch would require less parts. Pardon my ignorance.

Posted By: joshking440

Re: What Master Disconnect Switch?? - 06/30/09 10:16 PM

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Thanks a lot for the help guys! I've never installed one of these switches before.

If I get a 2 post switch, I will need a continuous duty relay for the alternator lead right? Wouldn't it be better just to get a switch with 4 posts so the relay won't be needed?

I like the FR switch and a S605 relay for the alt wire. You can always jumper around the relay if it fails. You're no different at that point than the guys that run the alt wire straight to the battery if it fails. I've not had a S605 fail yet, but carried a jumper wire just in case.

Thanks Rob. Is there an advantage to doing it that way versus just using a 4 post switch? It seems that using a 4 post switch would require less parts. Pardon my ignorance.

You dont have to run the alternator wires all the way back to the switch this way correct?

Posted By: mopowers

Re: What Master Disconnect Switch?? - 07/01/09 03:20 AM

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Thanks a lot for the help guys! I've never installed one of these switches before.

If I get a 2 post switch, I will need a continuous duty relay for the alternator lead right? Wouldn't it be better just to get a switch with 4 posts so the relay won't be needed?

I like the FR switch and a S605 relay for the alt wire. You can always jumper around the relay if it fails. You're no different at that point than the guys that run the alt wire straight to the battery if it fails. I've not had a S605 fail yet, but carried a jumper wire just in case.

Thanks Rob. Is there an advantage to doing it that way versus just using a 4 post switch? It seems that using a 4 post switch would require less parts. Pardon my ignorance.

BUMP?

Posted By: HealthServices

Re: What Master Disconnect Switch?? - 07/01/09 06:52 AM

Maybe not the best way but simple with a 4 prong disconnect and a 1 wire alternator

Attached picture 5326140-4prongdisconnect.jpg

Posted By: HealthServices

Re: What Master Disconnect Switch?? - 07/01/09 07:15 AM

Attached picture 5326155-4prongdisconnect2.jpg

Posted By: HealthServices

Re: What Master Disconnect Switch?? - 07/01/09 07:27 AM

I like the use of the ford solinoid for the starter. This way you can install the ford solinoid in the rear with the battery.

The big plus with this is the big battery cable is not hot when the car is running and you only need a small cable routed (and hot) to the front to keep the system running

Posted By: 70Cuda383

Re: What Master Disconnect Switch?? - 07/01/09 09:54 AM

do NOT buy the Jegs switch advertised as "250A 12V momentary, 125A continuous" because what it REALLY is, is 250A 6V momentary, 125A 12V momentary, and a 40A 6V, 20A 12V continuous rated switch.

I ended up with the moroso switch that was rated at something like 2000 amps momentary and 200 continuous?

$60 switch.

I have mine wired up like the 1st picture posted above, but instead of using the 4 prongs, I have the battery run back to the battery side of the switch on the large lug, and the small lugs are left empty/open, because they were only rated for like 10 or 20 amps, and my 120 amp alternator would cook them!

Posted By: HealthServices

Re: What Master Disconnect Switch?? - 07/01/09 02:17 PM

I think mine is like this. but I wish I used the method with the ford solinioid for the starter in the trunk. Whatever you do do it once because the likleyhood of you finding the time to change it in the future will be zero.

Attached picture 5326541-4prongdisconnect4.jpg

Attached picture 5326541-4prongdisconnect4.jpg

Posted By: HealthServices

Re: What Master Disconnect Switch?? - 07/01/09 03:13 PM

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Thanks a lot for the help guys! I've never installed one of these switches before.

If I get a 2 post switch, I will need a continuous duty relay for the alternator lead right? Wouldn't it be better just to get a switch with 4 posts so the relay won't be needed?

I like the FR switch and a S605 relay for the alt wire. You can always jumper around the relay if it fails. You're no different at that point than the guys that run the alt wire straight to the battery if it fails. I've not had a S605 fail yet, but carried a jumper wire just in case.

Thanks Rob. Is there an advantage to doing it that way versus just using a 4 post switch? It seems that using a 4 post switch would require less parts. Pardon my ignorance.

You don�t have to run the alternator wires all the way back to the switch this way correct?

No, but you do want to run the alternator wire to the battery side of the disconnect switch. Otherwise the car would not shut off when you flip the switch. The reason for the solinoid on the alternator is to have the ability to kill power outside of the trunk. Without this there is always voltage to the alternator.

Posted By: mopowers

Re: What Master Disconnect Switch?? - 07/01/09 03:45 PM

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No, but you do want to run the alternator wire to the battery side of the disconnect switch. Otherwise the car would not shut off when you flip the switch. The reason for the solinoid on the alternator is to have the ability to kill power outside of the trunk. Without this there is always voltage to the alternator.

I understand how to wire the 2 types of switches. I'm just curious, what are the pro's and cons of a 2 post vs. a 4 post switch for a street/strip car?

Posted By: HealthServices

Re: What Master Disconnect Switch?? - 07/01/09 04:12 PM

I do not see an advantage with using a solenoid vs. the 4 prong switch. The only reason I can think of why the solenoid came to be is because the 4 prong switch was not readily available back in the day, and like Tom said when they are available they may not have the load capacity (for the alternator amperage) that the solenoid has.

Just make sure if you do have a 4 prong it is rated at the capacity of your alternator's charging ability and the amount of draw you think you may experience.