roadtripper
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Post by roadtripper on Nov 22, 2017 7:43:15 GMT -8
On the 12 volt fuse panel side of a new PD converter, what’s the best way to size fuses for each circuit? A couple of examples:
If the water pump is rated max 7.5 A should the fuse for that circuit be just as close as possible to that rating. 10a ok?
If there are say 4 interior lights on one run, each with a led rated at 7 watts this is about .6 A x 4 = about 2 1/2 A total. Is a 5A fuse too much?
There are a few other circuits but all the same concept.
Thank you.
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mrmarty51
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Post by mrmarty51 on Nov 22, 2017 13:35:10 GMT -8
Fuses are to break the circuit in case there is a dead short to ground or an overload on any given circuit.
If You run 14 AWG wire, I would not be afraid to run 15 amp fuses in all of the circuits.
Even if the pump motor shorted out internally, it would be a greater than a 15 amp draw and burn out the fuse.
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roadtripper
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Post by roadtripper on Nov 22, 2017 16:38:00 GMT -8
Thanks Marty.
As this is an all new 12 v system I ran new 14 guage hot and ground to all items and have several circuits , so most things are isolated since I had the room.
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Post by bigbill on Nov 22, 2017 18:02:54 GMT -8
I some what agree with Marty but if I had a dedicated circuit for a given item such as a fan or a water pump I would fuse it no more than a few amps greater than what is needed. This will protect you from a dead short plus it will tell you if something is starting to create an additional load before you have a major failure costing more to repair than fixing the original problem. Fuses not only protect the circuit wires but also the items in the circuit which might have lighter duty wiring (smaller gauge) than the circuit. If you use lighter fuses and start blowing them you can check your load and increase as needed or figure out why they are failing if your existing fuse should be covering the load. This is why your 12 volt car has many different size fuses. Just my opinion.
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mrmarty51
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Post by mrmarty51 on Nov 22, 2017 19:10:25 GMT -8
I some what agree with Marty but if I had a dedicated circuit for a given item such as a fan or a water pump I would fuse it no more than a few amps greater than what is needed. This will protect you from a dead short plus it will tell you if something is starting to create an additional load before you have a major failure costing more to repair than fixing the original problem. Fuses not only protect the circuit wires but also the items in the circuit which might have lighter duty wiring (smaller gauge) than the circuit. If you use lighter fuses and start blowing them you can check your load and increase as needed or figure out why they are failing if your existing fuse should be covering the load. This is why your 12 volt car has many different size fuses. Just my opinion. Good points on that posting too. Sad thing is, most motors, like vent fans and water pumps dont have serviceable motors, so even with an early warning, not much can be done except to install a higher rated fuse. LOLOLOL |
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Post by vikx on Nov 22, 2017 21:55:22 GMT -8
30 amp fuses for 10ga wire
20 amp fuses for 12ga wire
15 amp fuses for 14ga wire
10 amp fuses for 16ga wire
These are maximums for the wire gauge. (Marty, I edited your post) If the item being run is listed at a lower amperage, it's OK to use a lower amp fuse. In other words, a 10 amp fuse is perfectly fine with 14ga wire. Just don't go over the 15 amp limit 14ga is capable of handling.
Hope this helps.
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mrmarty51
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Post by mrmarty51 on Nov 22, 2017 22:18:10 GMT -8
30 amp fuses for 10ga wire 20 amp fuses for 12ga wire 15 amp fuses for 14ga wire 10 amp fuses for 16ga wire These are maximums for the wire gauge. (Marty, I edited your post) If the item being run is listed at a lower amperage, it's OK to use a lower amp fuse. In other words, a 10 amp fuse is perfectly fine with 14ga wire. Just don't go over the 15 amp limit 14ga is capable of handling. Hope this helps. Thank You VickX i`m used to the auto industry, where a 20 amp fuse is common on 14 gauge wires. LOL |
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roadtripper
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Post by roadtripper on Nov 23, 2017 6:58:48 GMT -8
Thanks Marty, bigbill and Vikx for the quick help!
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