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well, now I know how fires start... that's been on my list of things to discover for a while now
I added two add'l engine room lights about two weeks ago. I wired them in series, tapping off the two existing lights. I installed a 12v/60w bulb in each and have been using them ever since. I noticed that the original two weren't as bright as they used to be but figured that probably made sense since I divided the circuit futher by adding the two additional lights.
I happened to reach into the storage area behind the helm (storage for me, I hinged the panel which is screwed in place) and accidentally touched the wires going to the switch. They were HOT and one of the connectors had turned black. Yikes....
The wire looks like it's 16/2 which should be able handle the roughly 20amps (240 watts/12) but doesn't account for the distance run which might be the difference. If it's 18/2 then I'm definitely over the limit.
Does anyone know what else is on the engine room lights circuit? I really don't want to add another circuit/switch so fluorescents might be the way to go.
You wired them in series ? I hope not .if you did the would be very dim if they worked at all . I am betting you did not , easy way to check is unscrew one bulb and if the all go out you did .
16 gage wire maybe to light if any length to the wire
Last edited by prowlersfish on Mon Dec 05, 2011 8:25 pm, edited 1 time in total.
Boating is good for the soul
77/78 TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat
prowlersfish wrote:You wired them in series ? I hope not .if you did the would be very dim if they worked at all . I am betting you did not , easy way to check is unscrew one bulb and if the all go out you did .
16 gage wire maybe to light if any length to the wire
+1
Jamie
1985 F-32 270 Crusaders
1988 Sea Ray 23 350 Merc.
Trojan. Enjoy the ride...
-I don't wanna hear anyone whine...Anymore!
-You might get there before me, but you still have to wait for me, for the fun to start!
By the way, THAT'S how I realized in 2005 that those panel switches were not switches at all, but actual individual breakers.
(I know I've mentioned that tip here as nauseum, but it's a real important safety issue that everyone needs to be aware of.)
My solution was to replace the higher wattage bulbs with the smallest 12volt I could find, still plenty of light and no issues. I just can's recall what wattage I ended up with.
RWS
1983 10 Meter SOLD after 21 years of adventures
Yanmar diesels
Solid Glass Hull
Woodless Stringers
Full Hull Liner
Survived Andrew Cat 5,Eye of Charley Cat 4, & Irma Cat 2
Trojan International Website: http://trojanboat.com/
Since I already have the lights, I'm going to replace the bulbs with 25w fluorescents which should drop the consumption from 20 to around 8 amps. No issue at thar draw.
I "jumped" each new light off an existing light so I guess those two are in series, the original two are not.
Speaking of breakers, I wish one have tripped right away. I had no idea what was going on and only found out accidentally.
If it was me I would want a minimum 14ga wire if not 12 ga to be safe. That long of a run in wire you may consider the 12ga and a heavier duty switch. Like a 50amp switch. But thats me.
Growing old is inevitable,but growing up is optional
1984 F36 w/350 Crusaders 'Reel Class'
2011 Trojan Rendevous
Solomons Get Together 2011
Ocean City 2012,2013,2015
The best rule of thumb for electrical wire size is #14 15 amps #12 20 amps #10 30 amps and #8 40 amps. When I wired my house this was the code. It would take a really big boat to exceed the recommended length of run for these wire sizes.
hey, current determines wire size. insulation determines voltage carring ability. 12 gauge will handle 20A. use stranded wire, not solid. are the flourscent bulbs made for 12vdc??
if you took 2 wires from the old lamp and connected them to the new lamp, (center to center and base to base) they would be wired in parallel, not series.
when you are comparing wattage of bulbs, the calculation is voltage x current = watts (power)
davidsmith wrote:The best rule of thumb for electrical wire size is #14 15 amps #12 20 amps #10 30 amps and #8 40 amps. When I wired my house this was the code. It would take a really big boat to exceed the recommended length of run for these wire sizes.
I believe thats specs for solid wire in an alternating current application. It may be close, but its definately not an analog for stranded wire in a direct current application.
DC voltage drop = current times resistance. Obviously different conductors will have different resistance properties. Make sure you select one that will still deliver the appropriate level of power (watts) to the lighting you are trying to run.
Its all in my book. "Phase Angle and You, A Guide To Inductive Reasoning"
1978 F-32 "Eclipse"
Merc 305 SBC's
1.52:1 Borg Warners
1983 Correct Craft
Commander 351 Ford (PCM)
1:1 Borg Warner
There are 350 different varieties of shark, not counting loan or pool.
I have a problem with stating that a given wire size will handle x amount of current. There are more variables involved to be making such generalized statements. It really depends on the cicuit in question, and typically every circuit is different. Even if the loads are the same current wise, wire runs locations, bundling, run lengths, and critical/non-critical considerations need to be taken into account. For example: technically 14 AWG wire will only carry 15 amps safely to a load that is 12.5 feet away. That's 25 feet of wire (in general 12.5 feet from supply to load and 12.5 feet back). That's for a 10% voltage drop circuit for non-critical systems like lighting. For critical systems circuits such as blowers, bilge pumps, nav lights etc., at 3% drop allowance, 14 AWG wire will only carry 10 amps for 10 feet of wire. That's a load that is 5 feet away from supply voltage. Same holds true for all other AWGs mentioned above, not including considerations to cable bundling and those running in engine compartments which reduce current handling capacities due to increased temperatures. The key is knowing the load, the distance of run (back and forth), critical circuit or not, and the route the wire will take. Then and only then can you correctly determine which size wire to use.
She was a 1969 36 ft wooden beauty with big blue 440s that we'll miss forever.
And thanks to the gang, 2012 Trojan Boater Of The Year
Ampacity of wire as stated is for solid wire. Actually multi-strand wire is rated somewhat higher. but for sure can carry what folks have stated given appropriate length analysis.
Larry Eddington
1984 F-36 Tri Cabin "The Phoenix II"
1978 F-28 "The Phoenix"
Fish Master 2350 Bay Boat
9.5' Dink
Capacity Chart
This chart is a simple "max capacity" chart for a short wire run. Increase the wire size for long runs - for example the wires running to the back of a vehicle to power the taillights may need to be one size larger to account for the length.
Stranded vs. Solid Wire
This one is a bit of a mind-boggler, but it's important. When electricity flows through a wire, it mostly flows on the surface of the wire, not through the middle. This effect is more pronounced on high frequency AC than it is on DC or low frequency AC. This means that a "wire" of a given size that made up of many smaller strands can carry more power than a solid wire - simply because the stranded wire has more surface area. This is one reason why battery cables in your car and welding cables are made up of many very fine strands of smaller wire - it allows them to safely carry more power with less of that power being dissipated as heat. However, this "skin" effect is not as pronounced in a typical 12V DC automotive application, and the wire and cable used there is stranded for flexibility reasons.
When looking at a chart or description of wire capacity, take note of whether it is referring to stranded or solid wire - some charts may not specify but instead assume a default based on the typical wiring used in a given application. For example, almost all automotive wiring is stranded while almost all home wiring is solid. For most applications, flexibility or the lack thereof will be more important, but for very high frequency AC applications, stranded wire might be a requirement.
