Fuses on a barrier strip?

[jwhite518]

Today I had my first look under the dash panels of my bike. The PO installed a barrier strip to feed his farkles. The positive terminal leading to the battery was fused, but none of the other wires leading to the barrier strip were fused. All the farkles are wired directly to the barrier stip. Is this OK? I'd feel better if my farkles were fused, especially the PHIDs. However there is very little room under the dash panels, so I can see that there were practical limitations.

 

[kaitsdad]

Jerry, es no bueno. Each device needs it's own fuse - your set-up is what's known as "pushing your luck."

What amperage is the hot feed fuse?

 

[ponyfool]

No, that's not good at all. Especially considering he probably had the barrier strip fused with a 10A to 30A fuse. For example, a GPS or radar detector only needs/wants a 3A fuse. Thus, an overload on the GPS/radar detector would fry the GPS/radar detector before blowing the 10-30A fuse.

 

[kaitsdad]

No, that's not good at all. Especially considering he probably had the barrier strip fused with a 10A to 30A fuse. For example, a GPS or radar detector only needs/wants a 3A fuse. Thus, an overload on the GPS/radar detector would fry the GPS/radar detector before blowing the 10-30A fuse.

Gunny !

 

[Checkswrecks]

No, that's not good at all. Especially considering he probably had the barrier strip fused with a 10A to 30A fuse. For example, a GPS or radar detector only needs/wants a 3A fuse. Thus, an overload on the GPS/radar detector would fry the GPS/radar detector before blowing the 10-30A fuse.

This is totally backward! The fuse is supposed to be sized for the wire and the wire is supposed to be sized for the device on the end. The idea is not to protect the device from an upstream overload, the idea is to protect the power source and distribution system from a short in a single circuit.

While I'll agree that you probably want a small fuse for each item, it's to cut off each wire (or the device it supplies) from taking out the rest of your electric system or even becoming an igniter if it hard-shorts to ground. Don't believe me? Take a piece of insulated wire and hold it with pliers to both battery terminals until it actually melts off an end. Now imagine that red hot wire, possibly with burning insulation, in a bundle of other wires under your fuel tank.

For more info, try the Littlefield designers guide or for something easier to understand read paragraph 11-48 of AC43.13 here.

Gee I go away for a week...

Bob

 

[jwhite518]

No, that's not good at all. Especially considering he probably had the barrier strip fused with a 10A to 30A fuse. For example, a GPS or radar detector only needs/wants a 3A fuse. Thus, an overload on the GPS/radar detector would fry the GPS/radar detector before blowing the 10-30A fuse.

This is totally backward! The fuse is supposed to be sized for the wire and the wire is supposed to be sized for the device on the end. The idea is not to protect the device from an upstream overload, the idea is to protect the power source and distribution system from a short in a single circuit.

While I'll agree that you probably want a small fuse for each item, it's to cut off each wire (or the device it supplies) from taking out the rest of your electric system or even becoming an igniter if it hard-shorts to ground. Don't believe me? Take a piece of insulated wire and hold it with pliers to both battery terminals until it actually melts off an end. Now imagine that red hot wire, possibly with burning insulation, in a bundle of other wires under your fuel tank.

For more info, try the Littlefield designers guide or for something easier to understand read paragraph 11-48 of AC43.13 here.

Gee I go away for a week...

Bob

Speaking of sizing the wire and fuse for the load....a pair of PHIDs is rated at 84W, which at 12V is 7A and requiring wire of at least 14AWG (if running them both off a common hot wire.)

So....I've read that the initial load to the PHID ballasts is greater than the 84W rated consumption. Anybody know what that number is?

 

[Bounce]

hell. there's little i don't run at least 12 ga wire to if i'm fabbing my own loom. if the oem device comes with something smaller (GPS for example) then i may choose to use that. everything else is 12 (lights, vest, etc.) or 10 (power block, etc.).

i'd rather over engineer the harness and let the fuse do the safety work.

 

[jwhite518]

hell. there's little i don't run at least 12 ga wire to if i'm fabbing my own loom. if the oem device comes with something smaller (GPS for example) then i may choose to use that. everything else is 12 (lights, vest, etc.) or 10 (power block, etc.).
i'd rather over engineer the harness and let the fuse do the safety work.

Sorry, the question was unclear. I was asking what the wattage draw is upon HID startup.

 

[Checkswrecks]

hell. there's little i don't run at least 12 ga wire to if i'm fabbing my own loom. if the oem device comes with something smaller (GPS for example) then i may choose to use that. everything else is 12 (lights, vest, etc.) or 10 (power block, etc.).
i'd rather over engineer the harness and let the fuse do the safety work.

Sorry, the question was unclear. I was asking what the wattage draw is upon HID startup.

I guess you could start by scaling this for your set. It's from the PIAA Canada web-site (1st thing on a google search):

PIAA’s HID bulbs, after that initial 25,000v arc to power up, run at 35w, which is significantly cooler than the halogen bulbs they replace. The output rating is closer to 150 watts.

Fortunately, starting current is brief, so the total energy isn't going to burn up properly-sized wiring. I also tend to just grab the roll of 12 gauge, but that's just being lazy and knowing it works for most things in a vehicle.

Bob