Line & load on circuit breakers

Thanks for your patience with my noob electrical questions!

I'm using the Tyco circuit breaker switches pretty much as Van's intended. So I take it the "line" terminal is the hot copper buss bar, and the "load" feeds the lights, fuel pump, whatever. So with the switches in the proper orientation (amp values on end of toggle reading right side up, where up is "on"), the buss bar should run along the bottom set of "line" terminals. I've seen some pictures where the buss bar runs across the top. Were these a case of incorrect wiring?

if your breaker specifies Line and Load, then the battery should be connected to the Line side, and the device should be hooked up to the Load side. Unless you are using an alarm'd breaker, it really shouldn't matter which way the breaker is actually installed.

Thanks. I felt a little dumb asking the question, but I wanted to be sure.

A few years back in the same place I asked Vans why their drawing showed the copper buss on the load side and the device on the line side. The person I talked with was unaware it was that way. Two electrical engineers said that would make no difference. Mine are working fine as thousands are. Do a little searching and you will earlier versions of this switch/breaker were the subject of an AD on some certified aircraft. Oh, and like everything else, some people love 'em, some hate 'em.

Called the Tyco manufacture and was told that it makes no difference. The military required the labels so they are labeled. A friend didn?t believe me, called them and got the same answer.
A note: If you install a Tyco CB switch on the same buss bar as a Tyco push pull CB one will be upside down according to the label so there you go. Larry

Thanks, guys. Looks like there's no wrong way to do it. I decided to mount the buss bar down low....plenty of clearance either way. I'm going with a combination of breaker switches and fuses, with the only pure breaker being a 60-amp for the alternator.

Just thinking about my breakers

Yesterday, I replaced the Tyco switch-breaker to my single navcomm --- the old switch-breaker FAILED in the CLOSED position --- in other words, would not shut off. No big deal, because I could turn off with the on-off switch on the Navcomm ------However, it got me thinking about what if the breaker had failed in the OPEN position ------ no navcomm! Obviously, a regular breaker could have the same failure modes, but they don't get cycled as much. ------- When I get a second navcomm, I will be certain they are on separate breakers (but still the switch-type).

rightrudder said:

Thanks, guys. Looks like there's no wrong way to do it. I decided to mount the buss bar down low....plenty of clearance either way. I'm going with a combination of breaker switches and fuses, with the only pure breaker being a 60-amp for the alternator.

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I just replaced my old non aircraft alternator with a B&C 40 amp alt/ regulator combo , I have the vans toggle type 5amp switch/ breaker for alt. on-off but do not have a (pure )dedicated alternator circuit breaker . Although I have purchased a 40 amp and intend on having it installed when I get my annual done in June . Is this feasible or should I install breaker now? Only reason I ask is because although I'm sure I'm capable of installing it myself I would prefer a more qualified person install it and at the moment I'm having no luck with that so I'm basically grounded . If I knew exactly where it should fall in line in the wiring schematic I would go ahead and install it now.

I suggest using a 50 amp ANL or MIDI fuse mounted to the engine side of the firewall near the starter contactor. See Bob Nuckolls' Z-11 diagram. The purpose of the fuse is to protect the battery from short circuits in the alternator or its wiring. If it ever blows, there is a serious problem that should wait to be solved on the ground. There is no need to run the heavy alternator "B" lead into the cockpit.

Mich48041 said:

I suggest using a 50 amp ANL or MIDI fuse mounted to the engine side of the firewall near the starter contactor. See Bob Nuckolls' Z-11 diagram. The purpose of the fuse is to protect the battery from short circuits in the alternator or its wiring. If it ever blows, there is a serious problem that should wait to be solved on the ground. There is no need to run the heavy alternator "B" lead into the cockpit.

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Thanks Joe that is helpful.