LippCJ7
Vice Admiral
- Joined
- Sep 20, 2010
- Messages
- 5,431
Re: 12 volt fuse box.
I agree but also disagree NYBo, the reason is that the fuse should protect the load from any further damage should a short occur in the load, obviously this would not apply in a light bulb since when it does blow what else can you damage, but if you take this several levels of loads higher, say in a two way radio worth $5000 and the power amplifier goes out it will blow the 30 amp main fuse, but since once the power enters the radio it then powers several different circuits within the radio, problem is if the main fuse didn't blow the other circuits would still be at risk. The same can be said about modern stereo's they are basically modules, CD player, Amplifier, Receiver etc. but there are not power leads for each individual module only a main power lead and an ignition sense which carry's no load at all, the same is true with high end Two Way radio's you have a transmitter, reciever, power amplifier VCO etc etc so in order to troubleshoot the main fuse being bad you unplug the radio and test the power cable for a short circuit via DVM, if the power cable tests good then the radio gets pulled, the radio is tested on the bench for the bad module which can be replaced.
Mixing loads on fuses only compounds the issue since now you have to test which load on the fuse shorted, if you were to say that you would use a 30 amp fuse to power your stereo and your depth finder but each of these loads would be fused properly after the 30 amp fuse I would have little issue with it other then its two more connections per load to corrode, then you apply power again to troubleshoot and the shorted load gets hit again which can cause further damage the shorted load.
I agree that the initial idea that a fuse is to protect the wiring, but that is no longer the only reason to fuse loads. In my experience if the load was installed properly it is unlikely that the wiring will ever cause a short anyway but you know the problem with this theory....."IF"!
If thats the way you want to do it I won't tell you its wrong I just wouldn't do it, I have seen it done a million times and corrected it nearly as many times as I have seen it, the main reason being is that if you take a police Car for example we have roughly 20-30 new electrical circuits to install into a Ford Crown Victoria, now if I have 2 or 3 that share fuses I had better know what fuse controls those 2 or 3 circuits, otherwise it looks like a pretty serious problem. I like how Silvertip says that there are two different electrical systems in a boat, I never thought of it that way but he is very correct, We do the same in Police Cars, you have the vehicle electrical system and then the emergency electrical system the only common factor in the two is the battery. The bottom line is that a fuse protects everything upstream of the fuse no matter if its the wiring or the load itself
I agree but also disagree NYBo, the reason is that the fuse should protect the load from any further damage should a short occur in the load, obviously this would not apply in a light bulb since when it does blow what else can you damage, but if you take this several levels of loads higher, say in a two way radio worth $5000 and the power amplifier goes out it will blow the 30 amp main fuse, but since once the power enters the radio it then powers several different circuits within the radio, problem is if the main fuse didn't blow the other circuits would still be at risk. The same can be said about modern stereo's they are basically modules, CD player, Amplifier, Receiver etc. but there are not power leads for each individual module only a main power lead and an ignition sense which carry's no load at all, the same is true with high end Two Way radio's you have a transmitter, reciever, power amplifier VCO etc etc so in order to troubleshoot the main fuse being bad you unplug the radio and test the power cable for a short circuit via DVM, if the power cable tests good then the radio gets pulled, the radio is tested on the bench for the bad module which can be replaced.
Mixing loads on fuses only compounds the issue since now you have to test which load on the fuse shorted, if you were to say that you would use a 30 amp fuse to power your stereo and your depth finder but each of these loads would be fused properly after the 30 amp fuse I would have little issue with it other then its two more connections per load to corrode, then you apply power again to troubleshoot and the shorted load gets hit again which can cause further damage the shorted load.
I agree that the initial idea that a fuse is to protect the wiring, but that is no longer the only reason to fuse loads. In my experience if the load was installed properly it is unlikely that the wiring will ever cause a short anyway but you know the problem with this theory....."IF"!
If thats the way you want to do it I won't tell you its wrong I just wouldn't do it, I have seen it done a million times and corrected it nearly as many times as I have seen it, the main reason being is that if you take a police Car for example we have roughly 20-30 new electrical circuits to install into a Ford Crown Victoria, now if I have 2 or 3 that share fuses I had better know what fuse controls those 2 or 3 circuits, otherwise it looks like a pretty serious problem. I like how Silvertip says that there are two different electrical systems in a boat, I never thought of it that way but he is very correct, We do the same in Police Cars, you have the vehicle electrical system and then the emergency electrical system the only common factor in the two is the battery. The bottom line is that a fuse protects everything upstream of the fuse no matter if its the wiring or the load itself
