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Old 04-27-2015, 07:45 AM   #111
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Quote:
Originally Posted by Lilcmp1 View Post
So I'm turning my short bus into an ice cream. The freezer only needs ~250W on startup. Could you recommend an inverter to use? Or what should I use for this? It's going to have to run directly off the battery?
Which freezer are you planning to use? A standard compressor based freezer will draw a pretty high peak current on startup. I've never measured it for a freezer compressor, but most electric motors need anywhere from 5 to 10 times their run current on startup. So your 250 watt running power could need 1,500 to 2,000 watts for a fraction of a second on startup. That's enough to trip the inverter over-current protection circuitry.

While very pricy, swing compressor freezers (Engel style) that run directly from 12-volts DC don't have an surge current issues, and would eliminate the need for a 120-volt AC inverter, which also induce their own power losses that adds to battery depletion.

So tell us what freezer and maybe we can come up with a plan.
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Old 04-27-2015, 10:10 AM   #112
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Originally Posted by family wagon View Post
Not to be a PITA.. but.. it'll be really difficult to keep the DC system isolated from the chassis because of items like the starter and alternator that are case grounded. Or maybe you were referring only to the house DC system rather than the vehicle DC system. Isolating just the house DC system from the chassis is very doable. I can understand the motivation to run ground return wires instead of using the chassis because body grounds seem to fail so often, but I admit I don't see a reason to go to any great trouble to ensure DC ground isolation.
I will be isolating all DC grounds.

Engine, trans, ect are all mounted on rubber mounts that make no steel to steel contact.

I'm rewiring my entire bus from scratch. Being I have a mechanical engine, this is doable.

Front engine is coming out in a few days. When I stick the 8.3 in the rear of the bus, All ground wires will lead back to a common ground bar.

Places like spring perches will be the only place I get any crossing of the grounds, but it will be minimal.

It sounds like a ton of work, but I'm wiring from scratch anyway, I may as well isolate the grounds.

Nat
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Old 04-27-2015, 10:32 AM   #113
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Originally Posted by family wagon View Post
For plastic conduit: the gray SCH40 PVC, or the corrugated blue "smurf" ENT tube, or is there another I don't know about? I like the idea of EMT because it's thinner but it does have all the down sides you described.
I've never used the blue stuff although I see it in construction projects a lot inside steel studs. I was talking about the grey PVC.

I mean, you don't even NEED conduit. This is all interior wall-space. The main goal is just to make it easy to run the wires, pull new ones some day, and provide some chafing resistance. Anything more than zero effort and you're already better than the average camper out there. Mine has romex just occasionally stapled to the 1" fir sticks used to (badly) frame the couch and cabinets. Between staples it just lays on the floor.

Quote:
Originally Posted by family wagon View Post
What about device boxes? I'm familiar with three types: the blue nail-on plastic designed for NM cable, the gray outdoor stuff intended for the PVC conduit, and a very limited selection of blue ENT boxes. I don't really want to use EMT.. but these plastic options all seem worse in their own ways.
I guess it's personal preference, but they do make a PVC-to-metal connector. It has a glue fitting on the PVC side and a threaded fitting that goes into a standard 1/2" or 3/4" metal box hole with the usual star-tooth nut.

A lot of this is just my opinion / my 2c. I'm not so much making a recommendation as I am sharing what I'm doing and why I believe it's appropriate. YMMV.

My plan: I personally like working with plastic conduit, I find it easy to alter later if I want to add a Tee or something, I like that it's waterproof and can't rust, and I like that it's not thermally conductive. (Junction boxes are common heat-loss areas.) I also like the vibration-resistance of a glued connection (although if you aren't trusting EMT as your actual ground, that's a minor thing). In my conduits (chases, really) I will pull stranded THHN, and use back-wired receptacles (they cost like $2.50 but I only need a handful - they have a special clamp plate for stranded wire).
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Old 04-27-2015, 07:08 PM   #114
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It will all be plastic boxes for me also.

Every wire will be in a plastic tube.

No wires will be run (pulled) till the bus is done. This will prevent any mechanical fasteners from piercing and wires.

Nat
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Old 04-28-2015, 08:38 AM   #115
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That's a good idea. I was considering the same myself (pulling the wires late in the game).

Those of you who think PVC conduit is overkill for things like LED lighting, but still want something to act as a "chase" in case you ever need to pull another wire, take a look at plastic shower curtain rod covers. I wouldn't put Romex in there, but for low-voltage small wires it makes a super-smooth sleeve, it's extremely lightweight, and very cheap. It's slit along the side so you can stuff an inch or two of the end of one piece into another to make a longer tube. They're super flimsy so they need support, but they're great for embedding in areas you plan to spray-foam.

I plan to use these in my ceilings for LED lighting.
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Old 04-28-2015, 09:03 AM   #116
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Quote:
Originally Posted by taskswap View Post
That's a good idea. I was considering the same myself (pulling the wires late in the game).

Those of you who think PVC conduit is overkill for things like LED lighting, but still want something to act as a "chase" in case you ever need to pull another wire, take a look at plastic shower curtain rod covers. I wouldn't put Romex in there, but for low-voltage small wires it makes a super-smooth sleeve, it's extremely lightweight, and very cheap. It's slit along the side so you can stuff an inch or two of the end of one piece into another to make a longer tube. They're super flimsy so they need support, but they're great for embedding in areas you plan to spray-foam.

I plan to use these in my ceilings for LED lighting.
I did the same with PEX for most of my 12v runs since I had plenty of it lying around. Super slipper and it can worm around obstacles. Wires push through it well even with curves.
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Old 04-28-2015, 10:00 AM   #117
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Here is what I used, plastic outdoor box with PVC flex conduit. I used 12 gauge stranded wire (essentially extension cord wire with an outer jacket over the triple wires) and insulated ground so the 120 volt ground is isolated from the chassis.



The wire is run into the stock C channel steel that the Thomas buses (and maybe others) have above the windows, where stock wiring is run. All my 120 volt wiring is surface-run, except that which is in the metal chase but that can easily be unscrewed, so if I want to add anything it is cake. Any exposed 12 volt DC wiring (fans in the emergency hatches, and other things I will add after the interior is built out) is run in 1/4" or 3/8" PEX tubing used as conduit that is surface mount. No photos handy but I just run a + line to the location and chassis ground it.



I just cut out a little bit of the C channel cover to get the conduit through, then ran the wire without conduit where it is not exposed.

Bonus:



Manual "transfer switch" from Blue Sea Systems. Most fcking expensive switch I have ever bought, it is a double pole, triple throw + off switch rated for 35 amps at 120 volts. So you can turn it off, 1 is plug in power, 2 is inverter power (elegantly just a plug into the inverter) and 3 is future use for if I ever have a chassis mount generator. With this switch you can have multiple inputs on at the same time (say inverter and grid power) and hot-switch them with no issue, just a bit of a flicker as it switches over. This switch is designed to disconnect one source before connecting another so it doesn't cross phases or whatever happens when you do that improperly.
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Old 04-28-2015, 01:15 PM   #118
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Originally Posted by jazty View Post
I did the same with PEX for most of my 12v runs since I had plenty of it lying around. Super slipper and it can worm around obstacles. Wires push through it well even with curves.
THAT's an interesting idea. PEX would be a really expensive option if you had to buy it, but if you have it lying around... I have like 100' of 1" that I used for a wood boiler installation last year. You're right - it's slippery. Would be easy to pull wires through...

I think the main downside with this is it's basically impossible to glue. It's also VERY stiff so going around corners is annoying...
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Old 04-28-2015, 01:17 PM   #119
Bus Nut
 
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Originally Posted by porkchopsandwiches View Post
Manual "transfer switch" from Blue Sea Systems. Most fcking expensive switch I have ever bought, it is a double pole, triple throw + off switch rated for 35 amps at 120 volts. So you can turn it off, 1 is plug in power, 2 is inverter power (elegantly just a plug into the inverter) and 3 is future use for if I ever have a chassis mount generator. With this switch you can have multiple inputs on at the same time (say inverter and grid power) and hot-switch them with no issue, just a bit of a flicker as it switches over. This switch is designed to disconnect one source before connecting another so it doesn't cross phases or whatever happens when you do that improperly.
Nice job, thanks for sharing!
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Old 04-28-2015, 01:20 PM   #120
Bus Crazy
 
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Quote:
Originally Posted by taskswap View Post
I think the main downside with this is it's basically impossible to glue. It's also VERY stiff so going around corners is annoying...
The PEX man's secret weapon: the heat gun! The PEX only needs to be warm for it to bend nicely. Once it cools it will usually hold close to the warm shape. Even a hair dryer will work.

You're right about not being able to glue it, though. That stuff puts up a hell of a fight against chemicals.

I used 1/2". Sometimes two parallel runs of it for getting lots of wires through.
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