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Old 07-26-2017, 05:14 PM   #1
Skoolie
 
Join Date: Dec 2015
Posts: 153
Prep for electric now hook up later?

I enthusiastically ordered some electrical equipment:
8x renogy 100w solar panels
Magnum ms2000 2000w true sine inverter/100a charger, single hard wired AC connection with transfer relay (I think it's the transfer relay that's 30amp)
500amp shunt
Magnum rc50 remote panel
Bogart trimetric battery monitor
Morningstar TS-MPPT-60 Tristar charge controller

I've got 10# wiring and connectors to run the panels in separate pairs to a box where I'll combine them with a bus bar with a big lug? I'll run #4 through the roof of the bus

My question is to allow myself to fully read and understand everything I may attach the panels and drop the cable through the roof and cap the wires off. I am running pvc chases so that I can run the wiring later. This way I can get the ceiling spray foamed before the snow flys allowing me to more comfortably work through the winter as I have limited free time and don't want to miss that opportunity to insulate the ceiling. I've got grey 1" ID and 3/4"ID to run above the windows on either side(will post pictured momentarily). I believe I read to run AC and DC separately which is my reasoning for the 2 chases. Each chase will cross the ceiling once in the front of the bus and once in the back via the blue flexible stuff with plastic boxes accessible at the Ts.

The reason I'm posting is because I started reading about the AC side of things and have realized that I need to do a lot more reading to ensure I do this right. If I were to run the chases wiring in the 3 AC outlet boxes that I will want with none of them making any metal connection to the bus I could get my ceiling spray foamed. I would run 12# wire and tape it hanging down where my 12v led ceiling lights will go (won't have chases for all of those)

This would give me time to ensure I understand the whole electrical system while allowing me to ensure my bus is insulated before winter.

I suppose I should mention that in terms of the AC side of things I only have a small chest freezer with mechanical temp bulb to shut off power to convert it to fridge. The other AC loads will be one for future TV eventually and laptop charging (probably won't use either for a while) and kitchen appliances (occasional crockpot, blender, and toaster oven if possible). Also have a 15k rooftop AC unit intended for shore power only. The goal is to run completely off solar with the ability to plug into shore if at a park for a while.

Any thoughts or advise?
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Old 07-26-2017, 06:03 PM   #2
Bus Crazy
 
Join Date: Feb 2012
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I can completely relate to the scramble for the season. I'm hurrying to get my sheet metal finished before I run out of 100-degree, or at least 95-plus, days. Right on its heels will come insulation.

Conduit is a great way to hedge for the future. You mentioned inside diameter of PVC chases so I'm not sure whether you're using regular gray PVC schedule 40 1/2" trade size, or a tube with actual 1/2" ID. The SCH40 PVC 1/2" trade size conduit has actual ID about 0.62". IMHO that's on the small side.. you can jam two pieces of 12-2 NM cable (Romex) in it if you pull them together, but I'm not sure whether that meets NEC conduit fill limits. "Electrician" isn't my day job, but for the most part I've learned that if I'm not really confident that 1/2" is large enough I probably should use 3/4" instead. The wire pulls easier and there's room to add something I'll be sure to want in the future.

Separate conduits for the AC and DC systems is a good idea.

Arrange things more or less in a "star" topology where everything comes together at one point. That's where your distribution panels will go. They tend to add up quickly in terms of size when you bring together an AC panel, DC panel, neatly routed cable, charge controller, inverter, transfer switch... Make sure it's a location with more room available than what you think it should need!
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Old 07-26-2017, 06:07 PM   #3
Bus Nut
 
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I try to keep my AC and DC wiring separate, but where they're close together I'll run the DC inside EMT conduit. I already use metal-clad AC cable, so I hope this will be enough to prevent one talking to the other. I have DC wiring chases above the windows for lighting, but my AC outlets will mostly be at floor level in a 1-1/4" wide space below the chair rail, behind removable sections of the Celtek wall covering for easy access.

It sounds like you're on the same track as me for your solar. I run my panels' power down inside the roof ribs and wall pillars all the way to the underfloor bays where my charge controllers are, so the 4AWG downfeed cables are protected but can still be pulled through if needed. I made a simple circuit breaker panel for some Carling Type C breakers, 50A for the panels' output to the CCs, and 80A for the CCs' output to the batteries. I also have a MS2000 and a pair of TS-MPPT-60s for the PV - all good stuff! I also will be using a fridger, maybe running off a second dedicated inverter such as a 300W Morningstar inverter (if it's big enough) or a 1100W Exeltech (NAWS has a good price on them) with its own separate AC line, leaving the Magnum just for the occasional big loads.

John
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Old 07-26-2017, 06:31 PM   #4
Bus Crazy
 
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John, this is a total thread-jack and I apologize in advance... I'm on the look-out for wall covering materials and noticed you mentioned Celtek in your post. I found an apparel company with that spelling, but nothing relevant to wall coverings. Is Celtec expanded PVC sheet from the sign-making industry the stuff you're referring to? I was surprised to learn just now that it has a flame spread index of just 20 -- much lower than wood products such as paneling, so I suppose this stuff would be a fairly safe alternative from a fire perspective.
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Old 07-26-2017, 07:27 PM   #5
Bus Geek
 
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Quote:
Originally Posted by family wagon View Post
you can jam two pieces of 12-2 NM cable (Romex) in it if you pull them together, but I'm not sure whether that meets NEC conduit fill limits. "Electrician" isn't my day job,
I am a little surprised. With your electrical knowledge and attention to NEC compliance i had you pegged for an pro electrician.

I don't think NEC allows NM in conduit. I have never seen mention of it in the NEC. Maybe I missed it?
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Old 07-26-2017, 08:13 PM   #6
Skoolie
 
Join Date: Dec 2015
Posts: 153
I have the 3/4 ID and 1"ID grey stuff. The pipes are touching each other. Is this likely to be an issue? I'm only running 3 AC outlet boxes and a rooftop AC. I think I can fit that in the 3/4 but I should check. The 1" I would hope will work for my DC. I am not sure how many DC wires I'll need to run yet. Do I run 2 from fuse box to appliance or 1. Can I split the DC wires to different things after they exit my grey conduit? Not sure if this helps but this is what I think I'll be running:

AC-
15k btu rooftop AC (to be used on shore power)
5 cubic ft chest freezer with mechanical sensor to cut power when at fridge temp
Occasional kitchen appliances if power permits (crock pot, maybe toaster oven or microwave)
Outlet in bedroom area for potential TV if we want one later and maybe laptop charging if we need it later.

I think this could be 3 outlet boxes because I imagine I want the fridge on its own?

DC
5a ceiling fan
3a water pump
3a On demand propane water heater
Little exhaust fan on composting toilet
2-4 USB chargers for phones and tablets
8 small ceiling lights
Need to look into those tape on side tank sensors for grey and fresh water
Smoke co2 detector.


I will also be hoping to run some heat tracing and heat pad to prevent plumbing under bus from freezing. Haven't done enough digging to see if that will have to be AC.

Not sure if the display panels for inverter remote and battery monitor need to be wired to my fuse box yet

I like the idea of running the solar through one of the bus ribs. Could I put my charge controller, inverter, fuse box and breaker box in a storage bay if they'll experience freezing temps? I'm guessing not but that would be right under where I plan my battery box.

Anywho does my conduit channels make sense given the stuff I want to run?
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Old 07-26-2017, 09:06 PM   #7
Bus Crazy
 
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Quote:
Originally Posted by PNW_Steve View Post
I am a little surprised. With your electrical knowledge and attention to NEC compliance i had you pegged for an pro electrician.

I don't think NEC allows NM in conduit. I have never seen mention of it in the NEC. Maybe I missed it?
Not too far off.. I suppose I should clarify. Electrical engineering is my main thing, though it has evolved to primarily low-level software in recent years. But I've played with electricity all my life and built half a dozen houses (meaning, at various times, operated the tractor to dig the hole, placed the concrete, framing, plumbing, electrical, insulation, roofing, drywall, exterior finishing, finish carpentry, etc). So I'm one of the few electrical engineers who understands how a 3-way switch circuit works -- many don't, I'm told. Along the way I've read most of the parts of NEC and IRC relevant to things I was doing in single-family residential construction. The core concepts I remember OK; the rest I know how to find in the code book when I need it. This time I was in a rush and didn't take the time to just look up a conduit fill table.

And so I'm a little embarrassed about the NM in conduit thing. I kinda think you're right about its use in conduit, except I did find just now a paragraph in the 2017 NEC partially allowing it. However, the heading above is "Exposed work" and so I'm left wondering whether this allowance applies only for exposed work and not for concealed work.. Anyway, here it is:
Quote:
Originally Posted by 2017 NFPA 70 334.15(B)
Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, ...
In any case I'd rather see somebody put NM in a conduit than put extension cords in a wall!

The air conditioner should have its own circuit. The rest could all be on a single circuit, but if you do have spare circuits lying around, use another for the microwave/toaster oven. It won't hurt anything to have a separate circuit for the freezer, but 5 cu ft is a pretty small unit and won't require much power. As far as number of outlet boxes: that just depends on how many outlets you want to have! Personally I like having sufficient outlets in the wall to minimize need for outlet strips, power taps, etc (the exceptions of course being temporary needs or electronics centers like an entertainment or computer area where it's just not realistic to have 10 sockets in the wall).

The AC and DC conduits side by side should work fine for you. From a noise pickup perspective more spacing is better, but you don't have any data or analog signals listed for that pipe, so extra spacing probably wouldn't make any practical difference for you.

You can run a single wire for supplying DC to those loads and let their negative return go via the chassis. In that case make sure the jumper from chassis to battery is adequate for the stuff you're adding. My preference is to just run two wires for my stuff instead of returning via the chassis.

Check the data sheets for the charge controller, inverter, etc. They should list high and low temperature limits for operating and for storage conditions. Fuses and breakers will surely be fine if exposed to sub-freezing temperatures.
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Old 07-26-2017, 09:27 PM   #8
Skoolie
 
Join Date: Dec 2015
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Quote:
Originally Posted by family wagon View Post
Not too far off.. I suppose I should clarify. Electrical engineering is my main thing, though it has evolved to primarily low-level software in recent years. But I've played with electricity all my life and built half a dozen houses (meaning, at various times, operated the tractor to dig the hole, placed the concrete, framing, plumbing, electrical, insulation, roofing, drywall, exterior finishing, finish carpentry, etc). So I'm one of the few electrical engineers who understands how a 3-way switch circuit works -- many don't, I'm told. Along the way I've read most of the parts of NEC and IRC relevant to things I was doing in single-family residential construction. The core concepts I remember OK; the rest I know how to find in the code book when I need it. This time I was in a rush and didn't take the time to just look up a conduit fill table.

And so I'm a little embarrassed about the NM in conduit thing. I kinda think you're right about its use in conduit, except I did find just now a paragraph in the 2017 NEC partially allowing it. However, the heading above is "Exposed work" and so I'm left wondering whether this allowance applies only for exposed work and not for concealed work.. Anyway, here it is:


In any case I'd rather see somebody put NM in a conduit than put extension cords in a wall!

The air conditioner should have its own circuit. The rest could all be on a single circuit, but if you do have spare circuits lying around, use another for the microwave/toaster oven. It won't hurt anything to have a separate circuit for the freezer, but 5 cu ft is a pretty small unit and won't require much power. As far as number of outlet boxes: that just depends on how many outlets you want to have! Personally I like having sufficient outlets in the wall to minimize need for outlet strips, power taps, etc (the exceptions of course being temporary needs or electronics centers like an entertainment or computer area where it's just not realistic to have 10 sockets in the wall).

The AC and DC conduits side by side should work fine for you. From a noise pickup perspective more spacing is better, but you don't have any data or analog signals listed for that pipe, so extra spacing probably wouldn't make any practical difference for you.

You can run a single wire for supplying DC to those loads and let their negative return go via the chassis. In that case make sure the jumper from chassis to battery is adequate for the stuff you're adding. My preference is to just run two wires for my stuff instead of returning via the chassis.

Check the data sheets for the charge controller, inverter, etc. They should list high and low temperature limits for operating and for storage conditions. Fuses and breakers will surely be fine if exposed to sub-freezing temperatures.
If I run one pos to all my 12v and a ground back to the battery I wouldn't have to ground each load? And I think I read in another thread that there would be no need to ground the neg terminal on the battery? Is there a downside to running the ground from all the 12v loads back to the battery? Would I want to go with 10 or 8# instead of 12? I feel like I expected to have more fuses... if I can run them all on one wire would I really want a DC fuse panel?

Any suggestions on a free app or Windows program to make wiring diagram? I have basically all the components I'm just struggling to connect the dots
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Old 07-26-2017, 11:38 PM   #9
Bus Nut
 
Join Date: Jun 2016
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Quote:
Originally Posted by family wagon View Post
John, this is a total thread-jack and I apologize in advance... I'm on the look-out for wall covering materials and noticed you mentioned Celtek in your post. I found an apparel company with that spelling, but nothing relevant to wall coverings. Is Celtec expanded PVC sheet from the sign-making industry the stuff you're referring to? I was surprised to learn just now that it has a flame spread index of just 20 -- much lower than wood products such as paneling, so I suppose this stuff would be a fairly safe alternative from a fire perspective.
Yup, that's the stuff. I think it's going to work well for me. I'm using 3/8" cheapo CD plywood behind it as a stiffener, then gluing the Celtek to the plywood. I've also decided to use it to cover the ceiling - I was originally thinking of using 1/4" cork sheet painted white, but I think I'll now use a thin dense foam and some white Celtek over that. I like the Celtek because it doesn't need painting and can be easily wiped clean, and it's flexible enough to be contoured against the ceiling. My three interior divider walls on each side will be better-quality 1/2" ply with Celtek on both sides, fitting inside 3/4" aluminum channel secured to the walls and ceiling and floor. It should look good when it's all done!

John
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Old 07-27-2017, 12:02 AM   #10
Bus Crazy
 
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Thanks for the tip on the Celtec. I'll have to look for a local distributor for it.

Each DC load is going to need a ground/negative. It can be via the chassis, the way the turn signal and clearance lights are done, or you can run a wire dedicated for it. The downside to running a wire rather than using the chassis is that you'll need twice as much wire (but I'd still do it that way).

The gauge of the wire depends on the current your loads require and how much voltage drop you want to tolerate. Voltage drop was a big deal for incandescent light bulbs because they go dim quickly as voltage drops. For modern LED lamps it depends: some designs have the LEDs right across the supply and these will dim with reduced voltage. Others have driver chips integrated with them; this kind (probably) won't show any dimming until the supply voltage gets really low. Unless you bought an LED lamp and cracked it open it'd be tough to know which kind of circuit it has inside.

I'd put the lights on a circuit of their own so that should something else burn a fuse, you won't find yourself having to fix it in the dark.

3A seems low for a water pump. As a single point of reference, the "SHURFLO® REVOLUTION™ Pump 12 VDC 3.0 GPM" is spec'ed by its manufacturer for a max of 7.5A while their 2.3 GPM is spec'ed at 5A. Having that fuse burn out while you're covered in shampoo lather in the shower is a bummer; I'd probably use a 10A fuse for either of these. Maybe your pump really is spec'ed for 3A because it has lower flow or something. The water pump is another item that'll suffer if its supply voltage is low, so the distance from the battery will factor into the minimum wire gauge.

Fuses are important especially for DC circuits because a DC arc doesn't self-extinguish the way an AC arc can/does. Even if you could put all that DC stuff on a single circuit with a 20-40 A fuse and #10 or #8 wire, it'd be better to break it up into smaller circuits.
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