Wiring interior lights

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Wiring interior lights

Postby ralaco » Sat Nov 05, 2005 7:16 pm

I’m wiring my trailer, but I have a doubt about how many fuses and wires to use with the double interior lights. :thinking:

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For these lights, do I have to use one (+ -) separate wire and fuse for each bulb or one (+ -) wire & one fuse for each two bulb units?

Raul
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Postby madjack » Sat Nov 05, 2005 7:23 pm

...one for each unit would be more than adequate in my book
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Postby vairman » Sat Nov 05, 2005 8:20 pm

The bulbs used in the lights are approx. 20-25 watts each, so you could use #14 wire with a 10-amp fuse and power both light sets off the same fuse...

4-25 watt bulbs =100 watts @ 12 volts = 8.33 amps
#14 wire is rated at 20 amps but is derated to 15 amps max. (safety factor)

Just my .02 worth

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Postby madjack » Sat Nov 05, 2005 10:49 pm

vairman wrote:The bulbs used in the lights are approx. 20-25 watts each, so you could use #14 wire with a 10-amp fuse and power both light sets off the same fuse...

4-25 watt bulbs =100 watts @ 12 volts = 8.33 amps
#14 wire is rated at 20 amps but is derated to 15 amps max. (safety factor)

Just my .02 worth

Greg :)


I wasn't gonna get that detailed but it is what I would actually do(maybe) but didn't want to start up with the electrical purist that want a seperate circuit/fuse to each fixture :o :D ;)
madjack

p.s. I can see both points(or all 3)
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Postby ralaco » Sat Nov 05, 2005 11:52 pm

madjack and Greg

I already bought a # 16 wire box so I will have to go with separate circuit/fuse to each fixture; my Circuit breaker is going to have about 15 fuses :cry: , but I think it will be very well protected.

:twisted:

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Postby bledsoe3 » Sun Nov 06, 2005 4:16 am

If you have that many fuses available (you should never need that many in a TD) put each light on its own fuse. You'll never have to worry about amp rating and if something happens to one light, the rest will still work. Thats how I would do it, IMHO. Jim
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Postby GeorgeTelford » Sun Nov 06, 2005 5:39 am

Hi

Its always good to have some of your lighting circuits on a seperate fuse, if you are away and a wire shorts behind a panel at least the lights on the other fused circuit will work, if they are all on one you have no lights.......
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Postby Arne » Sun Nov 06, 2005 7:07 am

My interior lights, fan, fantastic vent fan, reading lights, all run off heavy speaker wire and 1, 15a fuse.... the wire is that clear sheathed stuff with one copper colored lead and one silver lead, from home depot, bought by the foot.

Most of that stuff draws 2-4 amp at the most...... 40 watts draws a bit over 3 amps and the wire I used is easily good for 15 amps...

If you want to get a clue, take a look at the wire size inside the fuse... then look at your wire.... my wire diameter is approximately 3 times the size of the fuse..... no doubt the fuse will go before any damage occurs.
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Postby GeorgeTelford » Sun Nov 06, 2005 7:48 am

Hi Arnereil

No doubt you are right the fuse will go in time and all your systems would be down. If for some reason you cannot repair the cause of the fuse blowing (say it's hidden behind a panel) then until you get back to your shop everythings down and your weekend is ruined.

Fuse thickness and copper wire thickness will generally not bear any relation to each other, they are of differing materials. Fuse wire and other fuseable material is used for a specified purpose.
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Postby Arne » Sun Nov 06, 2005 8:33 am

You are right. Fuse wire can generally be of the same thickness as the power wire and will blow first.... I err on the side of safety, and to keep line loss at a minimum...... I have a 30 amp fuse at the battery with a 12 inch run to a fuse block, and my reading lights run off one 15 amp fuse, the fan, fanstastic fan and dome light off another 15 amp.... So, I could lose reading lights, or the rest, but none are weekend killers..... and the wiring is pretty simple, and most is buried in the walls.... if it works now, I expect it will be working in 10 years. The main connections are all easily accessed if I wanted to bother, behind lights or bezels.

The one thing I have to do, still, is get a 15 amp, 115v breaker, to put in the shore power line.... that wire feeds 3 power strips, one for general activities, one for a/c, tv, heater, and one for microwave and galley. All those are surge protectors with built-in circuit breakers, but I have no protection between shore power coming in at the wall, and the power strips.. will fix that this week.....

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I will off this general tip: where I run wire under the tear, through holes in the frame, I put a glob of silicone at each contact point to keep the wire from chafing.... All of it is sheathed, but this is an extra protection type thing......
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Postby GeorgeTelford » Sun Nov 06, 2005 9:51 am

Hi Arnereil

Which is it? in first post you have one 15A Fuse to run everything, which is the post that I commented on

My interior lights, fan, fantastic vent fan, reading lights, all run off heavy speaker wire and 1, 15a fuse

and then in the next post

my reading lights run off one 15 amp fuse, the fan, fanstastic fan and dome light off another 15 amp....
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