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-   -   do i need a relay? (http://www.wakeworld.com/forum/showthread.php?t=793188)

Topshelfbv 05-04-2012 11:59 AM

do i need a relay?
 
i installed one of skylons tower lights. there are 6 lights total 5 watts each. 10awg wire (2pos, 1neg) is run up to tower to power the lights. I have 2 switches wired one for the 2 forward lights with a inline 10 amp fuse, and and the other switch is for the rear 4 lights with a 20 amp in line fuse. both switches have a 30 amp rating. my question is do i need to add 2 relays to the circuit?

travisz 05-04-2012 12:02 PM

I would!

trdon 05-04-2012 3:00 PM

5 Watts is less than 1/2 amp per light so on the large load of 4 lights, you will have less than 2 amps on the circuit. The switches are rated for 30 amps, the switching is minimal. I would not do relays, and that is coming from an electrician. The rest is overkill too, I would just run 14awg wiring and 10 a fuses on bothbutt circuits, but separate grounds of 14 or a common 12. Just my .

501s 05-04-2012 11:55 PM

Agreed, no need for relays if your switches are rated for 30a.

nitrousbird 05-05-2012 5:06 AM

Quote:

Originally Posted by travisz (Post 1749502)
I would!

Please explain how you came up with poor advice.

The factory wouldn't use a relay in this situation. Let's make this a worst case scenario:

- All 6 bulbs on one switch/circuit
- All defective and pulling double their wattage (10 watts each)
- Battery is drained, and we are at 10V instead of 12+

This would have a total current draw of 6amps in a far than worst case scenario. Let's also go with an excessively long wire run of 30'. You can easily run this whole setup safely on 14awg wire straight to a switch.

A relay would add nothing but additional complexity and failure points to something that doesn't require a relay. The dock lights on my Malibu draw more than 6amps - yet they are ran straight to a switch. As is the heater, which I think is on a 20 or 30 amp breaker - straight to a switch.

In the actual real world application, 16awg wire would be acceptable. I personally would still run 14awg because price will be similar, and it's not much bigger so it won't be any more difficult to run.

Hell, my reversible ballast pump setup is hard wire to a switch, and those are rated to draw 13 amps/each at a constant rate and can spike higher. Switch to a circuit breaker.

Topshelfbv 05-05-2012 7:11 AM

Ok here is the deal I just had my boat summerized at local Malibu shop and the shop mechanic questioned me if I was going to add relays to the tower lights. He said " those things can really get hot. And draw a lot of current. I already ran the 3-10awg wires up tower because that is what was wired out of the light bar and wanted to match. I am using rocker switches that say 30a, I am not sure if that is peak or continuous or both. I understand ohms law just fine but when a mechanic from a reputable delarship advised it, I want to be sure. It would suck to burn my boat down because I thought" I know how what I am doing."

Topshelfbv 05-05-2012 9:23 AM

SORRY!!! I just looked and I wrote it down wrong the lamps are 55 watts each. So that would roughly be around 20 amps for rear and 10 for front depending on the supplied Vdc. Does that change any ones opinion out there. Again sorry for the typo.

501s 05-05-2012 12:23 PM

I actually had a feeling they were the 55watt lights you had, but throught maybe you had some 5watt LEDs. I had these 55watters on my previous boat. I used a relay. They cost like $5-$10 and are easy to hook up. In this case I'd use one.

trdon 05-05-2012 4:53 PM

Again, electricians advice,the switches are rated for it, but relay that thing. That is a lot of load for a switch and it will get hot. Typically, a general purpose relay will be rated for 30a as it is. But the contacts will be better suited for switching.

Topshelfbv 05-05-2012 9:14 PM

Thanks guys relays installed and work great.


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