Main Breaker in Front Storage Bay

jav9956 · February 04, 2016, 08:08:15 PM

Hello all.

My question is about the bus breaker box in the front storage bay. It has the A/C breaker etc in there. There is also the "Main Breaker".

I would like to take the excess guts out of the box as I removed the OTR components. I have left the drivers heater core and would like to potentially utilize that.

Does anyone know what I can and cannot take out of the breaker box? I was assuming that the "Main Breaker" is for the A/C system only but I feel that is a bad assumption which is why I have done nothing to it. It would be great to clean up excess wiring and tidy everything up before connecting to the batteries again.

Any info around this would be great. Haven't quite been able to narrow it done through use of the manual.

Thanks a ton in advance!

bevans6 · February 05, 2016, 12:30:27 AM

If your bus follows typical MCI practice there will be three breakers in that AC junction box. One is a 105 amp auto reset that connects the AC box bus bar to a cable that feeds the front electrical bay main bus bar and hence the whole front of the bus. One is a 105 amp manual reset breaker that feeds the AC condenser fan and the last is an 80 amp breaker that feeds the main AC and heater fan motor. There are probable other smaller breakers that feed AC control circuits. There should also be two relays that switch power to the fan motors. The AC junction box bus bar is fed by a 1 gauge wire from the bus battery cut-off switch. FWIW the rear junction box is fed from the large gauge wiring that connects to the alternator.

This is based on a circa 1980 MCI layout, but yours may be similar. If you plan on using the OTR heat but not the OTR AC, you still need to keep the fan blower relay and breaker, but you can lose the condenser fan relay and blower. I took them out and used the connection point to tie my house battery bank into the bus battery bank so the alternator charges my house system when the bus is running, and I use that connection to power my inverter to run my roof-top AC.

HTH, Brian

jav9956 · February 05, 2016, 04:32:42 AM

Thank you for the information. I definitely like the idea of utilizing the old tie in point to connect to the house batteries.

There is easy access to the breaker box itself but there is another box that all the wires seem to be fed into, it is in front of the breaker box (towards the front of the bus). I have not quite been able to gain access to it to investigate where all the wires lead. Thinking about it now I actually haven't taken a close enough look.

Do you know which box I am speaking of? And if so, any suggestions about how to access the innards? I am assuming if I get access to that I can trace the cables and remove the ones that are no longer needed (i.e. cables that run to the condenser fans etc).

bevans6 · February 05, 2016, 06:14:05 AM

If you get a manual you will find that every wire termination has a number tag on it that corresponds to the circuit id on the schematic, and the list circuit/stud connectors. My bus doesn't have a second box in the luggage bay that I can recall, just the AC junction box.

Brian

jav9956 · February 05, 2016, 07:17:59 AM

I have been reviewing the manual, I will do so again to see if it sheds new light on the issue.

The second box is not in the storage bay. It is near where the central heating core was, all the wires feed into it and then into the breaker box. I will just have to see what I can do.

I was looking through my pictures and did find one that kind of shows what I am talking about. In this picture you can see the breaker box. If you look a little further, toward the front of the bus (directly to the left of the breaker box if you are facing the breaker box), you will see all of the thick gauge black wire going into a box. That is the box in question.

jackhanow · February 05, 2016, 07:31:08 AM

I would just unhook the wires. If you start pulling the wires out, you may cause a short. Not sure what you would gain by doing more than just hooking up the battery bank. Just make sure to insulate the ends, and be careful not to unhook the wrong wire because some of the post are split into 2 circuits.

jackhanow · February 05, 2016, 08:20:18 AM

Are you sure those are all cables. That looks like the ac box under there or cut the rivets from the tin and see what's on the other side

jav9956 · February 05, 2016, 09:47:50 AM

That may be what I have to do to get inside. The reason I want to get in there is only because I removed the OTR A/C system (condenser, evaporator and central heating core) from the center of the bus. That has left some hefty gauge wire that led to the heater blowers/condenser fans... clearly I would rather have those completely removed then dangling or just cut and capped. I will try and get inside the box this weekend and see what I can see. I am sure it will be quite obvious where and what to remove, I have just been exercising caution and thought I would ask first and create more problems later

. I assume that box is just like a junction box. If anyone has more information please do share, always better to approach a task armed with knowledge!.

buswarrior · February 06, 2016, 10:35:17 AM

Check your electric schematics and see where your 102A air drier gets its power...

Earlier MCI are powered via the HVAC circuits, and has caused great frozen pneumatic frustration to busnuts who have torn out all the HVAC equipment.

happy coaching!
buswarrior

jav9956 · February 06, 2016, 03:29:25 PM

Thanks for the heads up.

I went in today and took the rivets/screws out holding what I thought was the top of a box (where the wires were going in). All it ended up being was an aluminum sheet fixed in place to hold the wires to keep from shifting about. Once I got the sheet bent up I was able to track the loose wires that I had floating around (the ones that went to the heater blowers and the condenser fans)... those came out without a problem. The rest of the wiring will stay because, as buswarrior mentioned above, it appears that many other circuits are running out the of remaining wiring. I am happy with what I have stripped out and everything still functions as needed. Maybe it is just me, but it worries me when wires are just bouncing around willy nilly

.

Happy to have this project done. Many more to complete this weekend. I will update my project page tomorrow night with all the goings on of the weekend!

Thank you all for your help.