Custom Coach - electrical questions

richard5933 · October 21, 2017, 02:49:52 AM

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

Jon · 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.

richard5933 · October 21, 2017, 05:16:30 AM

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

luvrbus · October 21, 2017, 06:34:06 AM

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

gumpy · October 21, 2017, 07:08:38 AM

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.

luvrbus · October 21, 2017, 07:27:22 AM

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

Oonrahnjay · October 21, 2017, 07:28:29 AM

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??)

gumpy · October 21, 2017, 07:52:24 AM

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.

richard5933 · 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? 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

eagle19952 · October 21, 2017, 08:17:28 AM

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

gumpy · October 21, 2017, 11:16:54 AM

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.

richard5933 · October 21, 2017, 11:53:46 AM

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

richard5933 · October 21, 2017, 04:50:28 PM

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.