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  #1  
Old 01-08-2011, 12:29 PM
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MSFT-1 MSFT-1 is offline
 
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Default circuit breaker question for the electrical gurus

I have the Van's HID landing lights on my RV-10 (one on the leading edge of each wing). They are wired to a single 10amp circuit breaker. Occasionally, when they have been on for several minutes (for a long taxi), the breaker will trip. After a couple minutes it will reset without issue. Most of the time this doesn't happen at all (I can leave the lights on for an hour with out a problem).

I am assuming that the lights are drawing enough current to cause that breaker to heat up and trip.

I asked an experienced builder if it made sense to up the breaker to 15amps. He said that might help but I needed to know the wire guage and length to properly determine the safe breaker size.

Can someone help me with this? What size wire should these lights use? How do I do the calculation?

thanks.
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  #2  
Old 01-08-2011, 12:33 PM
lucky lucky is offline
 
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Default I've got no idea but

I got all excited because I wasn't wearing my glasses and I thought you were asking about electrifying your RV's GUNS and I was thinking **** Yeah, Let's see this! Man, I'm disappointed....
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  #3  
Old 01-08-2011, 12:53 PM
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az_gila az_gila is offline
 
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Smile

The better idea might be to power them from two breakers not one for a slightly more redundant system.

Is each light switched separately?
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  #4  
Old 01-08-2011, 12:57 PM
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Mike S Mike S is offline
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Default

Quote:
Originally Posted by MSFT-1 View Post
I asked an experienced builder if it made sense to up the breaker to 15amps. He said that might help but I needed to know the wire guage and length to properly determine the safe breaker size.
Absolutely correct.

The breaker is there to protect the wiring.

I suggest going to individual breakers for each light.

You will then need to re-work the switching, a DPST switch will work, or add a second switch.
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  #5  
Old 01-08-2011, 01:36 PM
Lux Wrangler Lux Wrangler is offline
 
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Default real men don't

If all else fails, try reading the instructions, under "fuses and breakers":

"For each HID use a 10A" - Duckworks
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  #6  
Old 01-08-2011, 02:19 PM
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cfiidon cfiidon is offline
 
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Location: California
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Default Breaker versus wire size

Quote:
Originally Posted by MSFT-1 View Post

Can someone help me with this? What size wire should these lights use? How do I do the calculation?

thanks.
According to my trusty reference, protect 18 gauge wire with a 10 amp breaker, and 16 gauge wire with a 15 amp breaker.

So if you are wired with 16 gauge, feel free to just up the breaker size. You also might consider swapping out the breaker in case it's a "weak" one.

Don
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  #7  
Old 01-08-2011, 09:06 PM
SteinAir SteinAir is offline
 
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Location: Minneapolis
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Default

As others have pointed out, your choices are kind of limited by your wire size....if you have beefy enough wire then just put in a bigger breaker, if not then add a 2nd breaker or fuse. You're probably in the gray area of current draw being right on the edge of your breaker and environment (how hot things get under the panel, etc..).

My 2 cents as usual!

Cheers,
Stein

Last edited by SteinAir : 01-08-2011 at 09:16 PM.
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  #8  
Old 01-08-2011, 09:12 PM
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Ron Lee Ron Lee is offline
 
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Quote:
Originally Posted by Lux Wrangler View Post
If all else fails, try reading the instructions....
Cruel. That is against one of the Guy Code rules.
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  #9  
Old 01-09-2011, 07:54 AM
Lux Wrangler Lux Wrangler is offline
 
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Default I'm a man and I can change, if...

Quote:
Cruel. - Ron Lee
Well, I wasn't trying to be cruel. I have spent a many day-job-hours writting technical instructions that too few read. On the other hand; I think if I had been following the Red Green example, instead of spending so much time reading the instructions, I would be finished with my 7.
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Last edited by Lux Wrangler : 01-09-2011 at 08:08 AM.
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  #10  
Old 01-09-2011, 08:08 AM
Daver Daver is offline
 
Join Date: Nov 2006
Location: Albuquerque
Posts: 297
Default circuit length

circuit length has nothing to do with the circuit breaker.

The wire is sized to the load (upsized for voltage drop if necessary) and the circuit breaker sized to the wire.

Typically circuit breakers should not be loaded past 80% of the continuous load.

Dave
-9A flying
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