ok so i used my spare circuit in the cab for some green neons a long time ago, they pull .08A at startup and .06A steady after a millisecond, since that was so low, when i put in my 55W offroad lights i put them on the same circuit, it had a 10A fuse and was fine. One of the offroad bulbs blew, so i went to get a new one and saw they have 100W replacements, that fit the H3 style so i got them put them in and as soon as i hit the switch the fuse blew, so i ran a meter and it pulled around 18A at startup and settled to about 11.6A with the neons on too, so i threw in what i had (25A) which i know is wrong and ill change it tomorrow, but my question is, its all ran in 18G stranded, and so i dont blow fuses in the future i was going to put in a 20A but i think that may be to high for 18G, since it settles at 11.6A could i put a 15A fuse in? or would it blow for that millisecond it jumps to 18A when you turn it on?

 

bump.

 

I would think it will blow. Well it should a least.

 

try it and see. i suspect a 15 will work if the duration of the load is very short.

 

It's been a while since thinking about DC but
you're 55w lights at 12 volts = 4.6 amps so X 2 thats 9.2 amps
the 100w at 12 volts = 8.3 amps x 2 thats 16.6 amps

Why you're drawing 11.6? IDK unless you only changed 1 bulb... that is you have a 55 and 100w...
back on topic
you should bring that wire gauge up to at least 14awg probably 12 if the calculations are right, It's been a long day for me, (I can't think after 13hr day and now a 6pack) LOL
and the fuse WILL probably blow but not the first time you try it if the inrush is short, but the fuse will get weaker everytime the inrush hits it

 

is the wire gauge too small or will it burn up?

 

18 ga wire is only rated for about 9 amps, so you're pushing it, and it depends some on length.

a better solution would be to add a relay out near the lights, and pull a 12 or 14 qauge wire direct from the battery, through the relay, to the lights. you can use your existing wiring to turn on/off the relay.

 

i did a little research last month because i had the same questions. i posted that info for just this kind of question.

read this https://dodgeforum.com/forum/1906003-post41.html

i would tell you exactly what you need, but i would have to read that post again and i'm too tired for that.

 

Being an aircraft electrician I can tell you that pulling 18 amp at startup you will have to run a 20a fuse, that also depends on the quality of the fuse. Figuring in voltage drop and draw over a wire run of 15 feet you should be running a minimum of 12awg.