Docking Lights - Fuse too hot to touch

martybhawk · Apr 17, 2007

Just bought Pontoon boat - front docking lights not working - noticed on wiring block, one end of fuse holder had some melting and is disconnected from block and no fuse - if replace fuse, lights work but fuse gets so hot cannot touch it and I think it begins to smoke - if touch fuse holders together without fuse, lights work and it gets warm but not untouchable hot. Ideas?

bruceb58 · Apr 17, 2007

Re: Docking Lights - Fuse too hot to touch

Very possible that the fuse block got damaged for that particular terminal at some point and now has a hig resistance.

Do you have another spare fuse holder that you can move that circuit to?

martybhawk · Apr 17, 2007

Re: Docking Lights - Fuse too hot to touch

yes, I think there were 1 or 2 open spaces. I'm also not sure what amp fuse to use.

bruceb58 · Apr 17, 2007

Re: Docking Lights - Fuse too hot to touch

The docking lights I have seen run around 50W per light. Depending on your light and wire guage you would probably want a 15A or 20A fuse.

burroak · Apr 17, 2007

Re: Docking Lights - Fuse too hot to touch

If the docking lights are drawing that much current, you may want to consider a relay.

bruceb58 · Apr 17, 2007

Re: Docking Lights - Fuse too hot to touch

burroak said:
If the docking lights are drawing that much current, you may want to consider a relay.

Most switches are rated for 20A and most docking lights are 50W/each so the current can easily be handled by a switch.

I/O WALDO · Apr 21, 2007

Re: Docking Lights - Fuse too hot to touch

Probl;em is resistance at the fuse holder,knott the switch.Those pinch-type holders get a little corroded allowing the resistance on high load uses to rise,resistance is heat,the metal clip at the fuse looses it's temper and no more grip on the fuse! Needa dedicated 30 amp,sealed fuse holder connected to the main buss.

seamegr · Apr 22, 2007

Re: Docking Lights - Fuse too hot to touch

How about connecting an ammeter in line and see for sure what the current draw is at? Then you can do some simple ohm's law math to see if you need to install a relay. The relay would be a good idea anyway.

Greg

bruceb58 · Apr 22, 2007

Re: Docking Lights - Fuse too hot to touch

seamegr said:
The relay would be a good idea anyway.
Greg

I disagree. If there is no need to add a relay, I wouldn't add one. I subscribe to the KISS principle. If the docking lights are 50W/per, use just a switch.

Add another fuse block if the old one can't handle it.

drewpster · Apr 22, 2007

Re: Docking Lights - Fuse too hot to touch

I have seen this often in many fuse panels. The most common problem can be found in the panel itself. Normally there is a loose or corroded connection in the panel. If you can access the panel connections directly you may be able to repair it. The simple fix is to bypass the panel with an inline fuse or replace the panel.
I would check all of the circuit after the fuse panel to the lights, all the connections and the grounds, then replace the panel.
I think you will find that after the repair is made the lights will be brighter as well.

sbklf · Apr 23, 2007

Re: Docking Lights - Fuse too hot to touch

Short circuit protection (the fuse) is still required with a relay so this solves nothing. The problem is a loose connection. The wire size is effectivly reduced at a loose connection thus the heat (say a 16ga wire is reduced to a 26ga wire at a loose connection. A 16 ga wire will safely pass 12 amps but a 26ga wire will heat up and melt its insulation trying). Properly sized wire and devices will never be hot. Fuses are sized based on the ampacity of the wire they are protecting. Watts divided by volts = amps for a resistive load (lights) and you can add up the other loads to see what the current draw is for fuse selection and see if the wire is large enough.

I/O WALDO · Apr 23, 2007

Re: Docking Lights - Fuse too hot to touch

Fuse holder gets hot from high resistance caused by loose fuse clip to fuse connection... Relay makes no difference,like bruce says,KISS!Proper wire and switch size and good,tight connections is all it kneeds.Getta good ,30 amp fuse holder (pigtail type,with #12 wire)And wire it to the 12 volt feed.(Check the ground)Seems like the blade type(ATO) fuse holds up best.Usa 20 amp fuse

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