Electrical bus organization / side panels

[Zzz]

I'm looking for photos of your electrical bus organization and mounting. I've seen nice plywood used as a mounting surface for components. Just looking for ideas from builders who've completed theirs. Thanks.

[jaredyates]

I used fuse blocks for the electrical busses- one on the firewall right beside the battery (battery bus), and two on an aluminum sheet about the size of a dinner plate right by the right front seater's right knee.. The busses were no problem- the challenge came with organizing the various bits of the rest of the electrical architecture, including the regulator and capacitor for the standby alternator, and the ebus diode. I was using Bob's Z13/8. Are you going to be using one of his designs?

[Zzz]

Jared, I'm using a Vertical Power integrated breaker system, but stuff has to be collected physically somewhere.

I'm not familiar with Bob's electrical designs?

[N942VT]

Bob Nuckolls Aeroelectric Connection. I used fuse blocks also, on a swing down panel under the dash. It's been flawless for 400 hrs.

[Enewton57]

Look at the 3rd picture on this page of my website to see how I did mine:

http://mybearhawk.com/finish/electrical1.html

It's a hinged panel with the fuse block mounted to it. You can stand next to the airplane, reach in and open the panel and easily access it. No laying on your back with your feet out the windows. Easy access is good when you are old like me :-)


Eric Newton
Bearhawk Tailwheels LLC

Http://bhtailwheels.com

Bearhawk Builder Manuals

Http://mybearhawk.com

[jaredyates]

I haven't seen the VP parts in use in a Bearhawk yet. You should put together a Beartracks article when you get it all worked out!

[bestbearhawk1231]

Zzz, I am planning on using the vertical power set up if i can afford it when I get to that point. At this point I am planning on having a swing down panel on the copilot side for it to mount to and also protect it from water/physical damage. That way it is hidden from view until you need to add a circuit or perform maintenance. If I cannot afford the vp system I will be using a fuse block mounted in the same manner.

[fly_n_low]

Good ole fuse block mounted in the upper left of the firewall...

http://www.foxflier.com/bearhawk/2011/May11/P5210034.JPG

I've had circuit breakers in past aircraft and never used them. Buss fuses are the way to go.

Regards,

Ted

[marcusofcotton]

Lots of good posts here. Everyone remember CFR part 91.205(c)(6) if you want to fly VFR night or IFR:

"(6) One spare set of fuses, or three spare fuses of each kind required, that are accessible to the pilot in flight."

And yes, experimental are not exempt, should be in your ops limitations. In fact, be sure to request the pertinent phrase in your ops limitations, even if not currently equipping for night vfr or ifr. Then, if you ever might n the future, you may without troubles on this front. Without the phrase, you legally have a daytime vfr only machine.

When considering location, be thinking about how easily fuses can be changed while in flight, in the dark, with some turbulence thrown in as well.

Mark J

[jaredyates]

Lots of good posts here. Everyone remember CFR part 91.205(c)(6) if you want to fly VFR night or IFR:
(6) One spare set of fuses, or three spare fuses of each kind required, that are accessible to the pilot in flight."

Mark makes a great point. This is why I've not made my fuses accessible to the pilot. In our airplane, fuses are a ground maintenance item and not a flying pilot item.

[Zzz]

Is there similar wording in regard to resettable breakers? Common sense suggests that a tripping breaker shouldn't be reset more than once as it could be indicative of a problem that may be exacerbated with resetting.

[Battson]

Seems most aircraft around here are using 95% CBs, are fuses still widely used? I don't think I've really flown an aircraft which was primarily fused. Carrying delicate spares seems like a pain.....? And changing fuses in flight? No thanks!
I used a few fuses, but only where the amperage was too low for a common CB to trip fast enough. Stuff like the GPS and small panel lights, non-critical stuff.

Resetting CBs - we were always trained that you waited a few moments for things to cool down in case something had overheated, then try resetting the CB not more than one time. If it tripped again, you probably have a hard fault.

In the 300hrs, I've had 2x transient faults on the alternator excitation circuit. No idea what they were, couldn't find them, but in each case I was pleased to re-close the CB without it tripping again.

[Zzz]

I think some builders use fuses because they are lighter weight and don't take up any panel space, and they are simple and cheap. In my case, the VP unit will weigh a little more, and cost a little more, but like a hidden fuse block, it won't take up any panel space and makes wiring simpler.

[jaredyates]

Bob Nuckolls makes a good argument for why fuses (like the blade fuses in modern cars) can be a better choice for our application than circuit breakers. He also makes the case for why alternators should have "crowbar overvoltage protection," a type of system that includes a circuit breaker for the alternator field wire. The only two breakers that I have are for the two alternator field wires. Jonathan, I don't know anything about the regulations in NZ- there may be something in your regulations that lead more people to choose breakers. I find that electrical system understanding is not universal though, especially among home builders, so it may not be best to look for norms in deciding how to design a safe and reliable system.

Another key component of his designs is active notification to the pilot of voltage below alternator voltage. This gives the pilot time to realize that he's depleting finite battery power, so that he can configure the load appropriately before the battery is drained beyond use. As he says, almost all of the dark and stormy night stories of fading radio lights would be eliminated with this simple addition.

Fuses and breakers are intended to protect wire, so the current draw of the device is not really as applicable to the protection device rating as the wire size. I didn't use anything smaller than 22-gauge wire, which depending on the bundling and the length of the run, is generally good for a 5A fuse. If a 1-amp load is connected to a 22 gauge wire, the fuse can be sized for 22 gauge wire. If the same load is connected with a 10-gauge wire, then the fuse can be sized for that wire. AC43-13 has the chart that specifies which fuse size is associated with which wire size. Putting a smaller fuse in place isn't going to cause any problem as long as it is big enough to supply what the device needs, but it seems like that's a common misunderstanding.

Electrical planning is not any more complex than other aspects of plane building, but it is still worth learning enough about to get it right. Bob's book, the Aeroelectric Connection, is long and informative. If a builder doesn't want to spend the time to read it all, I'd suggest that every airplane builder at least read chapter 17 before doing any airplane wiring, or making any electrical planning decisions. There's no point guessing about this sort of thing when the information is so readily available.

[marcusofcotton]

Is there similar wording in regard to resettable breakers? Common sense suggests that a tripping breaker shouldn't be reset more than once as it could be indicative of a problem that may be exacerbated with resetting.

Nada. Battson's advice is common and sound imho.