I've searched high and low. Still can't find the fuse panel for the 12v house system. Anyone have experience with Custom Coach conversions that might know where to look?
Here's the main controll panel, which is located above the driver on the side. It contains the 120v breakers. I've opened the front of the panel (it's hinged) but there are no fuses, just terminal strips. Is it possible that they built the coach without fuses?
Richard (https://uploads.tapatalk-cdn.com/20171018/aa816c767bff339cacf2c451d609391a.jpg)
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB
The 12v fuse are in the converter box on my buddy's Custom Coach 4108
Quote from: luvrbus on October 18, 2017, 02:58:20 PM
The 12v fuse are in the converter box on my buddy's Custom Coach 4108
Do you mean the bay with the dc power converters/chargers?
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB
I've expanded the title to this thread, as the electrical oddities of Custom Coach go far beyond not being able to find a 12vdc fuse panel. I know that this was the epitome of bus conversions in 1974 when this bus was done, but I would assume that even then there were already some standards for things like connecting an RV to a campsite.
After seeing the details of this Custom Coach conversion first-hand, I'm even more strongly convinced that our 4106 was also done originally by Custom Coach. There are too many similarities, down to the type of wire used and how the vinyl trim is fastened on the ceiling for it to be just a coincidence. The method used to connect the generator to the house wiring is also identical. That's the focus of this post.
The bus has a Kohler 12.5kw genset, same as the 4106. Also like the 4106, the genset is connected to the 120 house wiring panel by using two hot conductors (L1 & L2). Each of these powers one side of the panel. There is a third conductor from the genset, and it is a bonded ground/neutral. It runs to the 120v panel as such, a bonded ground/neutral. If the bus were never to be connected to shore power, then this would be okay. Not ideal, but okay. The problem comes when trying to connect to a modern RV hookup.
Custom Coach used what today would be a 30-amp three conductor receptacle on the bus. There is a 3 conductor cordset that looks like it plugs into a regular 30-outlet. Problem is, the receptacle on the side of the bus is wired with L1, L2, and the bonded ground/neutral. If I use a modern 30-amp cordset to plug into a modern 30-amp outlet, I'm connecting it to L1, neutral, and a separate ground. There is no L2. Only half the 120 panel will have power.
According to the wiring diagrams, it looks like they shipped the bus with a custom made cordset and adapters. I don't have these.
When I got our first bus, the 4106, I worked with an electrician friend of mine to update the bus to modern 50-amp wiring. We separated the ground from neutral on all the 120v circuits. It was pretty easy the 120v panel was a Square D residential box in the closet with lots of room to work. My friend explained that when connected to the house, the bus was essentially a sub panel and should not have a bonded neutral/ground. So that's what we did.
On our new bus the 120v panel is mounted above the driver's seat. It's the part to the left of the photo I posted earlier. I think they used a marine type of panel for this. There is no way to just add a separate bus bar and break out the ground from neutral. Also, the wiring harness/loom is strung so neatly and tucked in so tightly that I don't think there is room to really move things very much at all.
So, finally my question. I'm going to get my electrician to chime in tomorrow, but I want to know from bus people how this sounds.
What if I just use the wiring diagrams to recreate what the bus shipped with originally, and make an adapter that will allow me to pick up L1 & L2 from the 50-amp outlet in the pedestal at our house and keep the bus with a bonded ground/neutral. Apparently it's been used that way for 43 years. There are breakers to protect all the 120v circuits in the bus.
Hope I'm not opening a can of worms, but I would like to know what others would do in a situation like this. My goal is to keep as much as the bus original as possible, and to change what is practical to update for safety.
Richard
First, the neutral and ground should be bonded at the source. i.e. when connected to shore power, it is bonded in the house panel and should not be bonded in the bus. When the generator is producing power, it should be bonded at the generator, which is appears to be based on your description. When an inverter is producing power, it should be bonded at the inverter. There are a few ways to accomplish this. One is a transfer switch. Another is separate sockets which you manually switch a pigtail between, depending on what source you desire to use.
Second, If your bus is wired for 50 amp service to shore line, just buy a dogbone connector for 30 amp service. This connection has the two hot wires tied together internally, so when you plug into 30 amp post, it will power both sides of the breaker box on the one hot leg coming from the power post. If your bus is only wired for 30 amp shore power, then consider the individual sockets I alluded to above and to the crossover inside the shore power plug.
Quote from: gumpy on October 19, 2017, 12:23:20 PM
First, the neutral and ground should be bonded at the source. i.e. when connected to shore power, it is bonded in the house panel and should not be bonded in the bus. When the generator is producing power, it should be bonded at the generator, which is appears to be based on your description. When an inverter is producing power, it should be bonded at the inverter. There are a few ways to accomplish this. One is a transfer switch. Another is separate sockets which you manually switch a pigtail between, depending on what source you desire to use.
Second, If your bus is wired for 50 amp service to shore line, just buy a dogbone connector for 30 amp service. This connection has the two hot wires tied together internally, so when you plug into 30 amp post, it will power both sides of the breaker box on the one hot leg coming from the power post. If your bus is only wired for 30 amp shore power, then consider the individual sockets I alluded to above and to the crossover inside the shore power plug.
I understand what you're saying that only the source should be bonded, whether it be the generator, the shore power, or the inverter. Unfortunately they didn't know that at Custom Coach in 1974. Actually, I have heard that in some areas of the country things used to be done differently with regard to bonding neutral/ground. The 120v panel on the bus has bonded neutral/ground. It would need to be totally redone to change that, as the wiring hasn't got a spare inch to move any thing to separate things out.
It appears that the bus is wired for 50-amp service. However, this was accomplished through the use of a 3-conductor receptacle - I'm guessing because that's all they had in 1974 to work with. The 3-conductor is wired L1, L2, bonded neutral/ground. I know that's not what it should be, but it is. Apparently they've used it for 43 years this way.
I checked with the electrician that helped me re-do our first coach to bring it into this century. He said that while not ideal, continuing to run as is will work for the short term. All I need to do is re-create the original adapter spec'd out in the wiring diagram so that I can plug the bus into a modern 50-amp outlet. Eventually we'll figure out how to break out the ground/neutral and run a proper 50-amp setup throughout the bus.
There are so many oddities of the electrical system on this coach that I want to run as is if possible just to see what is powered by what. For example, there is really no house battery setup. There is a 12v 8D battery on the generator. It's not deep cycle, but it is used to run the 12v systems on the bus. I think that they planned to be on generator or shore power nearly all the time. There are also a lot of house systems running on the chassis 24v battery bank. Also not deep cycle. These are mainly lights but also include the water pump and some of the solenoids for the pneumatic controls for things like the stair well cover.
Once I fully understand how things are currently running I'll start drawing up plans to break it down and create it with a proper house battery bank.
Any insights would be welcome.
Again, before you recreate the adapter from their drawings, maybe you can post the drawings here. I suspect the standard 30-50 amp dogleg adapter from any RV supply store and most WalMarts will probably do what you need.
I bet Grumpy is right, a 30 -> 50 dogbone should connect L1 on the 30 amp side with L1 and L2 on the 50 amp side. I have two adapters plugged into mine right now, a 15 -> 30, and then a 30 -> 50, and both L1 and L2 have power.
The 30 -> 50 was $15 from amazon.com, seems up to the task.
https://www.amazon.com/Camco-55185-PowerGrip-Dogbone-Electrical/dp/B000BUQOGI/ref=sr_1_3?ie=UTF8&qid=1508468086&sr=8-3&keywords=30+to+50+amp+rv+adapter (https://www.amazon.com/Camco-55185-PowerGrip-Dogbone-Electrical/dp/B000BUQOGI/ref=sr_1_3?ie=UTF8&qid=1508468086&sr=8-3&keywords=30+to+50+amp+rv+adapter)
BTW, that electrical panel is dead sexy. That coach is a pure time capsule, what a find!
Quote from: j.m.jackson on October 19, 2017, 07:56:12 PM
I bet Grumpy is right, a 30 -> 50 dogbone should connect L1 on the 30 amp side with L1 and L2 on the 50 amp side. I have two adapters plugged into mine right now, a 15 -> 30, and then a 30 -> 50, and both L1 and L2 have power.
Be careful of those 15 -> 30 adapters. Some have been known to get hot and melt the cover, even without an excess load on them.
The 15 -> 30 cord I use looks just like the 30 -> 50, it's a plug, 1ft of cord, and a socket. Ive run a 13500 btu ac, drill, 4.5" grinder, and shop vac on it. I've purposely checked the temp of the plugs and extension cord I use after running the above to make sure nothings getting hot. I've had good luck so far. I'm about 75ft away from the gfi socket that I'm plugged into. Purely temp tho while remodeling the 5303, need to put a 50 amp socket on the house.
Sounds like a lot of unique build methods of the CCC. Did you get connected to the CCC Facebook group? It seems topics like this would get responses from those who have wrestled with this sort of thing
Quote from: windtrader on October 19, 2017, 09:30:34 PM
Sounds like a lot of unique build methods of the CCC. Did you get connected to the CCC Facebook group? It seems topics like this would get responses from those who have wrestled with this sort of thing
Couldn't find the Facebook group for them.
Richard
Quote from: j.m.jackson on October 19, 2017, 07:56:12 PMI bet Grumpy is right, a 30 -> 50 dogbone should connect L1 on the 30 amp side with L1 and L2 on the 50 amp side. I have two adapters plugged into mine right now, a 15 -> 30, and then a 30 -> 50, and both L1 and L2 have power.
The 30 -> 50 was $15 from amazon.com, seems up to the task.
https://www.amazon.com/Camco-55185-PowerGrip-Dogbone-Electrical/dp/B000BUQOGI/ref=sr_1_3?ie=UTF8&qid=1508468086&sr=8-3&keywords=30+to+50+amp+rv+adapter (https://www.amazon.com/Camco-55185-PowerGrip-Dogbone-Electrical/dp/B000BUQOGI/ref=sr_1_3?ie=UTF8&qid=1508468086&sr=8-3&keywords=30+to+50+amp+rv+adapter)
Something about this bothers me. Richard ways that his coach was wired for 50Amps with a three-pin socket/plug. That would be a NEMA 10-50 (if the ground terminal is flat and the other two at an angle to each other) or 6-50 (if the ground terminal is round or "arched" - half a square with a radiused top side - with the other two terminals parallel to each other). The dogbone that you show here* has a NEMA TT-30 (the "standard" RV/Trailer 30Amp/120V plug socket) but is had the other end a NEMA 4-pin, 10-50 socket. If Richard has the three-pin plug (of either type), it's not going to fit into the four-pin socket on the dogbone.
He'll have to make up a special connector with a socket that matches the plug on his cord (including checking that it is actually 50Amps/240Volts on a three-pin plug and not 30Amps/120Volts on the three-pin RV plug -- MANY people have burned out RV systems --
see http://noshockzone.org/accidentally-plugging-into-240-volt-outlet/ (http://noshockzone.org/accidentally-plugging-into-240-volt-outlet/) -- by plugging a 120V system into a 240V outlet) with a RV-type TT-30 plug on the other end.
It's always something that gets in the way of making it simple.
(Speaking of this dogbone that lets you connect a plug on your shore-cord that's 4-pin/50Amps on a system that wired at the breaker for two split 120V legs and plug the other end of the dogbone into a 30Amp RV socket, isn't there a reverse? If the only receptacle available is 240V/50Amps and you have a three-wire 120V system on your bus/RV/trailer with a three-pin TT-30 plug on the shore cord, you'd need a dogbone that gives you a 4-pin plug on one end with a connector to only one hot leg that goes to a 30Amp RV socket to match the shore cord's plug, right? I know that most campsites with pedestals for RV's that have 240/50Amp/4-pin sockets usually have a 120/30Amp/3-pin socket and also a "household" 120/15Amp/3-pin extension cord socket, but I bet that there are some situations where you may have only 240/4-pin socket and 15Amp socket but if a vehicle is wired with the 30-Amp plug on the shore cord, you need an adapter for that situation.)
Yes, Richard stated that the plug on the bus looks like what is today a 30 amp TT plug, but is not wired as such. If it were mine, I'd swap that out for a standard 50 amp inlet plug so that there is NO CONFUSION when plugging into today's adapters, cords, and TT outlets. IF the coach is only rated at 30 amps, then use a proper 30 amp breaker on the bus side to protect it, maybe in a disconnect box near the inlet
Quote from: j.m.jackson on October 20, 2017, 05:34:06 AMYes, Richard stated that the plug on the bus looks like what is today a 30 amp TT plug, but is not wired as such. If it were mine, I'd swap that out for a standard 50 amp inlet plug so that there is NO CONFUSION when plugging into today's adapters, cords, and TT outlets. IF the coach is only rated at 30 amps, then use a proper 30 amp breaker on the bus side to protect it, maybe in a disconnect box near the inlet
Yeah, this is a confusing mess. The 30-Amp TT-30 connectors (round ground, two angled blade pins - one hot, one neutral) looks very much like the 5-50 connector (blade ground/neutral together, two angled blade pins, both hot at 120V) and the 6-50 connector (round ground, two parallel blades, one wide and one narrow). If Richard's new bus is indeed 240V wired at the breaker box then he needs a 4-conductor cord with a 14-50 four-pin plug on it and a compatible 4-pin socket to plug it into. If it's wired 120V by separating the legs at the breaker box, he needs the same kind of cord and plug. If it's wired for 120V at the breaker box, and he puts that cord and plug on it, he can plug into a 240V outlet and be OK, or he can use a dogbone plugged into a 30Amp socket and connect his shore cord to the 4-pin socket on the dogbone. Only thing is, wired for 120V on the bus and plugged into a 30Amp receptacle on the pedestal, he can't run 240V appliances, even though he's got 240V connectors on his shore cord.
Maybe these photos will help.
The bus is wired like a modern 50-amp coach, except for the connections being 3 conductor instead of 4. They did that by using a bonded neutral/ground.
If there's room, maybe the simplest thing to do is swap the receptacle on the side of the bus for a modern 50-amp version. Othwise, I could create my own adapter.
Can you guys verify which type of connector they used from the photos? There's two of the receptacle (one open, one closed), on of the other end of the cordset, and one of the appropriate wiring diagram.
Richard (https://uploads.tapatalk-cdn.com/20171020/e0595ab6e71b11f6e091f9e6f761dc11.jpg)(https://uploads.tapatalk-cdn.com/20171020/8941a9a2531339d5bbf13ef8825c69b2.jpg)(https://uploads.tapatalk-cdn.com/20171020/71f3bd4dc0ab8cd81854e0ecab4e2ac1.jpg)(https://uploads.tapatalk-cdn.com/20171020/5570ba9865e7cb2d8f4d64f6c58c185f.jpg)
Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB
That's a hubbell twist lock connector, rated for 50 amps at 250vdc/600vac. If that cap is threaded, it may be the 'standard' marine 50 amp hookup.
It's actually pretty nice in that it won't fall or pull out. It can actually support a separate neutral and ground connector, if you want to make up an adapter cord for it. The diagrams you included above show that.
Below is the current 'standard' 50 amp marine locking socket and lineset. I don't know if it's exactly the same, but it's very similar (with the sliding ground connector on the shell)
Socket:
http://www.adventurerv.net/cynder-rvmarine-easy-twist-lock-inlet-standard-amp-125250-marine-p-33151.html (http://www.adventurerv.net/cynder-rvmarine-easy-twist-lock-inlet-standard-amp-125250-marine-p-33151.html)
Pre-Made cord to standard 50 amp RV plug:
http://www.adventurerv.net/marine-power-cord-amp-with-marinco-hubbell-locking-connector-p-22804.html (http://www.adventurerv.net/marine-power-cord-amp-with-marinco-hubbell-locking-connector-p-22804.html)
???
how do you get 50 amp service from 3 wires...?
The case of the connector is ground. L1, L2, and neutral are the pins.
Look at the adapter diagram, you'll see the adapter in the upper left is the 5-15 plug (110v) and they short the L1 and L2 pins together to power both sides of the panel.
The diagram in the middle of the page shows all 4 conductors with L1, L2, Neutral, and Ground. Ground doesn't have a separate pin, it's the case of the connector. But from the diagram, Neutral and Ground are not connected together.
Edited to remove "not ever", as we don't know if neutral is connected to the body at any point, or if the sockets in the unit are grounded to ground, or connected to neutral. It would be interesting to see if there is continuity between the neutral pin and the body.
Richard,
Here's the link to the CCC FB group. https://www.facebook.com/groups/542130302637631 (https://www.facebook.com/groups/542130302637631)
Buck trout admins this group. https://www.facebook.com/buck.trout.7 (https://www.facebook.com/buck.trout.7)
If you have trouble getting in let me know.
Don
Quote from: j.m.jackson on October 20, 2017, 10:30:42 AM
The case of the connector is ground. L1, L2, and neutral are the pins.
Look at the adapter diagram, you'll see the adapter in the upper left is the 5-15 plug (110v) and they short the L1 and L2 pins together to power both sides of the panel.
The diagram in the middle of the page shows all 4 conductors with L1, L2, Neutral, and Ground. Ground doesn't have a separate pin, it's the case of the connector. But from the diagram, Neutral and Ground are not connected together.
Edited to remove "not ever", as we don't know if neutral is connected to the body at any point, or if the sockets in the unit are grounded to ground, or connected to neutral. It would be interesting to see if there is continuity between the neutral pin and the body.
The 15-amp adapter does bond L1 & L2. That's not my worry.
If you look at the bottom right of the diagram, you'll see that from the input receptacle to the transfer switch they use only three wires.
Here's a photo showing the inside of the panel where those three wires go after the transfer switch. Left side of panel is fed by black. Right side by white. Top (bonded neutral/ground) is fed by green.
Richard
On genny that's OK but not on shore or some inverter's. It could create a hot-skin condition. Shore power should only be bonded at the pole or house main panels.
Quote from: Dave5Cs on October 20, 2017, 03:04:13 PM
On genny that's OK but not on shore or some inverter's. It could create a hot-skin condition. Shore power should only be bonded at the pole or house main panels.
I agree. Any idea when they stopped making them this way?
Until I can figure out how to separate neutral/ground, I need to figure out how to use this as is so I can charge batteries and test the systems.
If I understand what you're saying, if we have a short from hot to neutral/ground in the bus, the skin will be energized. I imagine that the biggest danger is being in contact with the bus skin and earth simultaneously. Correct?
Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB
Especially when wet or if raining and say you touch the skin and are standing in a puddle. People have actually died this way.
Please test the skin. If you have a Multimeter. Plug the shore cord into the bus first and then with no one on board or around the bus but you plug the house side in.
Use the + prob and touch the metal skin of the bus and put the other prob into the neutral of a cord plugged into a grounded outlet. If there is a hot-skin condition you will see a current reading on your meter. if it is a GFCI outlet it should pop the breaker. HTH
Also check if there is continuity between the skin (ground) and the neutral leg. You should be able to do that without plugging it in at all.
Quote from: j.m.jackson on October 20, 2017, 03:59:42 PMAlso check if there is continuity between the skin (ground) and the neutral leg. You should be able to do that without plugging it in at all.
If the bus has a bonded neutral/ground, then won't there always be continuity between them?
Isn't it current between hot and bus skin (neutral/ground ) that I'm worried about?
Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB
In looking over the wiring diagram again, I see mention of 'grounding clip'.
Did they used to run the fourth (ground) wire from bus chassis to pedestal ground this way? I'm going to crack open one of the ends of the original shore cord tomorrow and see what's inside. Maybe there is a fourth conductor?
The diagram shows four wires in the shore cord, I suspect you'll find 4. The 4 th wire should goto the shell of the connector, for ground. The connector on the side of the bus is 4 conductor. Three pins plus the shell for ground. The 'clip' I suspect would be on the shore end of the cord to clip to the conduit or something on the shore end for ground.
Nowadays, there is a dedicated ground pin on the shore side.
Yes, hot on the skin is a worry, but the ground should drain that away.
The transfer switch may connect neutral to ground when switched to gen, but may separate them when set to shore. It's definitely something to check so you know.
According to what I see in the drawings, the neutral and ground are separate, not bonded. Neutral comes into the bus in the cable as white, but they run neutral from the inlet to the panel as green. This is the biggest problem I see. The color of neutral should be white, not green, and the color of the hots should be black and red, not white. Ground comes in from the cable as green and is bonded to the case of the connector, which is bonding the entire bus frame to ground by the fact that the connector is attached to the body. Now, if there is not a neutral to ground bond within the panel or elsewhere in the bus (e.g. in the generator), then the bonding will be properly NOT bonded. However, I think we've already seen that they are bonded in the generator. I suspect they simply used a 3 conductor 120v 8 ga cable to run from the inlet to the panel rather than a proper 4 conductor 240v cable of proper size.
Quote from: gumpy on October 20, 2017, 09:25:56 PM
According to what I see in the drawings, the neutral and ground are separate, not bonded. Neutral comes into the bus in the cable as white, but they run neutral from the inlet to the panel as green. This is the biggest problem I see. The color of neutral should be white, not green, and the color of the hots should be black and red, not white. Ground comes in from the cable as green and is bonded to the case of the connector, which is bonding the entire bus frame to ground by the fact that the connector is attached to the body. Now, if there is not a neutral to ground bond within the panel or elsewhere in the bus (e.g. in the generator), then the bonding will be properly NOT bonded. However, I think we've already seen that they are bonded in the generator. I suspect they simply used a 3 conductor 120v 8 ga cable to run from the inlet to the panel rather than a proper 4 conductor 240v cable of proper size.
It's hard to see in the little photo of the opened panel, but the left side of the panel is fed by black. The right side is fed by white. The neutral comes to the top bus of the box on the green. There are also red, green, and a few white wires coming into the top of the box - these are apparently both grounds and neutrals. They did not follow anything close to what we would call a standard color coding, although all the hots do appear to be black going to the outlets and loads.
I'll dig into it more and see what I can find on the back side of the inlet.
Richard
Without looking at the plug configurations at all my very strong opinion is the coach is set up for 30 amp shore power.
Unless I am reading it wrong the wiring size is #10 and unless or until a lot of rewiring takes place all the coach can handle is 30 amp shore power.
Quote from: Jon on October 21, 2017, 03:34:06 AM
Without looking at the plug configurations at all my very strong opinion is the coach is set up for 30 amp shore power.
Unless I am reading it wrong the wiring size is #10 and unless or until a lot of rewiring takes place all the coach can handle is 30 amp shore power.
Jon,
I agree about the wiring size being smaller than what is used on today's 50-amp service. The last coach we had was wired the same as this, and when we first connected we used a standard 30-amp cordset like you'd find on any modern RV. The problem we ran into is that only half of the 120v panel was powered.
The folks at Custom Coach definitely wired this coach the same. They also definitely have two hot conductors coming in to the 120v panel. They come from the transfer switch, and both the shore power inlet and the genset input to the transfer switch have two hot conductors.
At this point I just want to find a way to get the panel powered so that I can test the equipment and such. I'd power up the generator to do that, but it's another story altogether. I have not gone through the basic engine maintenance yet (oil change, filters, etc) and there is an exhaust leak. The engine on it runs, but that's all I know. So, that leaves me with figuring out something to get started.
Richard
Quote from: Jon on October 21, 2017, 03:34:06 AM
Without looking at the plug configurations at all my very strong opinion is the coach is set up for 30 amp shore power.
Unless I am reading it wrong the wiring size is #10 and unless or until a lot of rewiring takes place all the coach can handle is 30 amp shore power.
Yea it is set up for 30 amps the 50 amp was unheard of in 70's for a RV even into the early 80's some of those had a switch where you manually changed from 1 ac unit to the other because both would not run on 30 amps,you needed the generator to run both AC units
According to the drawings, the coach and cable have a 50 amp connector. However the cable is 10 ga which is good for 30 amps and the coach is 8 ga which is good for 40 amps.
I just never saw a RV from the 60's and 70's even into the early 80's wired for 50 amps service 50 amp service wasn't available at the camp grounds
Quote from: richard5933 on October 21, 2017, 05:16:30 AM... The folks at Custom Coach definitely wired this coach the same. They also definitely have two hot conductors coming in to the 120v panel. They come from the transfer switch, and both the shore power inlet and the genset input to the transfer switch have two hot conductors. ...
I think that the issue come in whether the bus is wired internally to maintain the 240V from the plug. As you know, 240V is comprised of two legs of 120V. I think that the way the bus is wired is that it's all 120V but really there are two side-by-side 120V sistems. When you plug into a 30Amp 120 socket, you have to have a "jumper" somewhere in the system (probably in the dogbone or "hockey puck" adapter) that shares the power from that socket across the two house systems. When you plug into a 240V socket, you're pulling 120V from each hot terminal to have two 120V feeds -- one into each half of your house system. (The use of the proprietary "Hubbell" socket and plug sets kinda makes my brain hurt but it's just a connector.)
If you say that when you plug it into a usual 120V/30Amp socket and only half the breaker box has power, I think that that indicates that you're only feeding hot power to one half of the electrical system on the bus. If it's set up the way I think it is, if you have a plug hard-wired or an adapter that connects to a 240V outlet, you're "connected to 240V" but from the plug or adapter, you're really running 120V. Which goes back to the question, which is the correct and efficient and safe plug or adapter to get power for you to set up and test your bus system?
Richard, can you post a photo of the plug on your shore-cable, and also a photo of the wall socket that you're plugging into? My feeble little mind is thinking that that is a picture that I need in my head to help complete my understanding of what you have. Thanks (and I hope that my poor explanations aren't just muddying the water).
BH NC USA
(PS - A question for those people who are familiar with those Hubbell connector sets -- are they set up with the connector pins to match any of the standard NEMA connection standards or are they a size/type/layout that's specific to the Hubbell components??)
Quote from: Oonrahnjay on October 21, 2017, 07:28:29 AM
(PS - A question for those people who are familiar with those Hubbell connector sets -- are they set up with the connector pins to match any of the standard NEMA connection standards or are they a size/type/layout that's specific to the Hubbell components??)
Bruce, see the photos on page 2 of this thread. The Hubbell is the connector with the flip up cover. Three twist lock pins in a circle and a ground point on the inner ring of the cover. Top and bottom photo. The cord end is the third photo between the knees, although that's not the end that plugs into the bus. That's the end that plugs into the pigtail adapters coming from the power box.
It appears that the shore cord is 10 ga 4-conductor. If the current is split between the two hot conductors, wouldn't that be 60 amps total coming through the shore cord? I looked at the Hubbell marine products brochure, and then still manufacture 60-amp products for use on boats. The photo I posted earlier is the end of the cord that plugs into the pedestal. I'm guessing that they used the marine products because they wanted more than 30 amps and there wasn't much else available at the time. There is room for a proper 50-amp inlet to be installed, but the cable running from the inlet to the transfer switch has zero extra length for maneuvering.
Seems like all the above would match the power provided by the genset which has 2x 30-amp breakers on the control box for the generator. (It's a 12.5 kw Kohler)
If I swap out the 2x 50-amp breakers in our pedestal for 2x 30-amp breakers, I should be able to swap out the pedestal end of the existing shore cord for a modern 4-conductor 50-amp plug, then plug in and at least be able to run from home. I know that there is always the danger of someone unknowingly plugging into a pedestal with 50-amp breakers, but there are just two adults involved in this and for now it may be the best option to get testing done while at home over the winter.
For use at a campsite I'll have to somehow create breakers between the bus and the pedestal to limit the draw on the shore cord to 2x 30 amps. As it is things would work by plugging directly into the 50-amp outlet, but then the breakers would not protect the cord in the event we draw too much juice. Probably could accomplish this by adding an outlet and pigtail to a small disconnect box like in this photo. Kind of awkward, but at least we'd be able to get going for now.
For information's sake, there are no 240v appliances on the bus. The biggest draws come from the two basement air units, the microwave, electric water heater, and two-burner electric hotplate. There are also three electric heaters, each appearing to be 1500 watts. I'm guessing that the bus was used on generator most of the time, but with only 950 hours on the genset (and the barely-used interior) it doesn't look like they did all that much camping over the past 43 years. The original owner of the bus owned a charter bus company in NJ (Super Service) and I'd guess that he had a pedestal custom installed to match the plug on the end of the shore cord. Looks like that's what we're going to need to do as well.
Richard
there are and has been two cardinal rules of wiring.
white is always neutral
neutral is never switched except in motor OL's
no electrician since ball and knob BWE has violated it.
it may be 240v service
but it can't be 50 amp
i know they made red wire back in the day
i find it hard to believe an outfit like CC woudn't use it.
even in the rarest event that white is used as a conductor NEC says it is to be marked (taped) entirely inside the enclosure
3M makes 24 colors for this purpose
The NEC has been around since about 1913
Quote from: richard5933 on October 21, 2017, 07:55:44 AM
It appears that the shore cord is 10 ga 4-conductor. If the current is split between the two hot conductors, wouldn't that be 60 amps total coming through the shore cord?
No. The 30 amp shore plug has a 30 amp breaker which would trip if you exceeded that between the two sides. Remember the two hots are combined in the adapter. It's only a single hot in the 30 amp plug.
Quote from: gumpy on October 21, 2017, 11:16:54 AM
No. The 30 amp shore plug has a 30 amp breaker which would trip if you exceeded that between the two sides. Remember the two hots are combined in the adapter. It's only a single hot in the 30 amp plug.
That's why I thought about using a 50-amp plug for now. Combined with the proper 30-amp breakers, I could power the two hot legs at 30 amps each.
Why CC used the colors they did is something I can't answer. Maybe because they were making use of the cable they had on hand. When I get things rewired I'll correct that. For now, I want to be able to get the thing plugged in, have appropriate breaker protection, and evaluate what works and what needs to be replaced.
Richard
1974 GMC P8M4108A-125 (Current bus)
1964 GM PD4106-2412 (totalled Sept 2017)
Located in beautiful Wisconsin
KD9GRB
Here's what I did so far with pretty good results:
- Plugged the existing shore cord (4-conductor) into the inlet of the bus. Removed the other end so that I could see wire colors and use test meter.
- Tested ends of shore cord and found the following: Red is connected to bus neutral. Black to L1, White to L2. Green to ground. Did not find any continuity between either L1 or L2 and ground/neutral with breakers all off.
- With transfer switch in off position, ground and neutral not connected at inlet. With transfer switch is shore power position ground and neutral are connected. Conclusion is that bus is wired with a bonded neutral/ground panel.
- Connected 'standard' 50-amp plug (NEMA 14-50, I think) to end of existing shore cord, adjusting for odd color schematic.
- Changed breakers in my pedestal for the 50-amp outlet to 2 x 30 amps (instead of existing 2 x 50 amps).
- With all power off, plugged in. Started with just turning on the outlets. Inserted outlet tester and all lights indicated a proper ground and properly wired outlet.
More testing to do tomorrow, but for now I suspect that what I've got is a poorly color coded wiring job setup for 60-amp service (2 hots @ 30 amps each). Given the use of an inlet rated at 65 amps that would make sense. I'm going to assume that this is how CC did things, as this is the second of their coaches I've had and both had nearly the identical electrical setup.
I'm planning to do a series of additional checks tomorrow to make sure that there is no current to the bus skin when connected, and then proceed to doing the same testing when breakers are turned on one at a time.
Not done yet. But on the way to making this coach function in the 21st century.