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You should plan a good 'safety factor' when you have calculated 'normal' current draw. 150% of total possible draw would be reasonable; some would prefer to double the actual value to protect against wiring failures/insulation fires. Just a thought........
Using a 15A fuse on a 14A circuit and a 30A fuse on a 28A circuit is asking for trouble.Using a 20 or 25A fuse on the low and a 40A fuse on the high would be more suitable.
Incandecent lamps draw higher wattage with higher voltage., as do all resistive loads.They may see 14-15 volts.
Key that in, and up a wire size.
No such thing as too large a conductor.
In buildings we never excede 80 % of conductor rating, but then again, AC has a slew of other issues.
Using a 15A fuse on a 14A circuit and a 30A fuse on a 28A circuit is asking for trouble.Using a 20 or 25A fuse on the low and a 40A fuse on the high would be more suitable.
Perhaps I need to word my question differently. I have four headlamps in an automotive circuit. The total load will be fed by the proper size wire. However each lamp will have a short length, less than 6-inches, of smaller wire rated to handle approximately 130% of that resistor. Is it considered safe to do this?
Yes.
The fuse will protect the circuit, and a dead short will pop the fuse.
That "tap" is protected by the load.
Ever notice a flourescent ballast has #18 leads, but is tied into a 20 amp circuit? That is called impedence protected.
Yes.
The fuse will protect the circuit, and a dead short will pop the fuse.
That "tap" is protected by the load.
Ever notice a flourescent ballast has #18 leads, but is tied into a 20 amp circuit? That is called impedence protected.
Gotcha. The "tap" is the same thing as the short length of wire between the battery and the fuse.
I'm not following your new question or following why you are posting about the current of the stock wire when you have posted a schematic using relays to power the lights. When using relays there should be no reason to use a wire gauge lighter than what the circuit needs. The relay and fuse parts you have picked are too light duty if they have pigtails that are too small a wire gauge.
I'm just trying to figure out how much wire that I have to replace. And get the sizes right so I only do it once. Also document the change to make it easy on the next owner. No one wants to buy a car with hacked up ameatuer wiring.
Tonight I completed the wiring from the lamps onto the conduit T on the driver's side, adjacent to the alternator. Along with the hot side I added a new 12ga ground to each lamp, tieing in the existing grounds. Pain in the **** job since you have to work through the cooling air intake. All uninsulated mechanical crimp terminals, then heat shrink tubes for insulation. I used all the original conduit and clamps, except for a splice that would not go back in. Old fashioned tape wrap sealed that up, and I use Scotch 33+.
I reinstalled the headlamps with the 60/55 H4 bulbs so I can use the car until I have time to do the render. Everything works.
Next I'll put in the fuses. Actually self-resetting circuit breakers. I'll mount those to the firewall next to my new fuse panel. I'll use the area where the anti-theft switch is, since I abandoned that system.
Then I'll put in relays next to the conduit T, since that's were the green and the wires from the OE switches pass through.
Here's the install. Self-resetting breakers wired to the new main panel.
I made a block from 1/2" thick HDPE sheet to mount the breakers on:
Put the new power wires in woven sheath and routed them along side other conduits and vacuum lines:
New relays mounted inside the fender, driver's side. Everything is grounded to the alternator body through the original conduit tee. All splices are uninsulated butt with double crimps and heat shrink insulation. I'll sheath this like the power wires.
End result is that the 60/55 watt H4 conversion bulbs mounted now are much brighter than before. When I put the 100/80 watt bubs I fully expect to burn a hole in the back wall of the garage.
