enblethen writes "The 120 volt wiring should be type NM... ...Do not use single strand wire for 120 circuit..."
Type NM AKA ROMEX is only available in SOLID strand in 14 ga and 12 ga. You statement specifically states to "Do not use single strand wire for 120 circuit" which does not make any sense since SOLID wire is the only way you can buy NM aka ROMEX.
I think you meant Do not use solid wire for 12V, in other words use STRANDED wire for 12V.
MrWizard writes "16ga is more than enough for 12v lighting
12v power circuits for TV's fans inverter's should be sized to the device"
Disaggree, this is the total opposite of standard industry practice. You select fuse size to protect the WIRE.
Generally add on devices must contain internally a fuse, fusable link, fusable resistor. The only device I know of that really doesn't have a fuse is 12V light fixtures unless they are LED or flourescent. But then one could argue that the lighter ga wire inside the fixture is a fusable link.
you misunderstand..what i am saying.. the fuse in panel is sized for the wire, it is there to protect wiring. but 16ga wire is heavy enough to power 12v lighting, and a 10-12amp fuse will be find for 12v lights, look at the wiring in most RV 12v lights, it is NOT 14 ga, yet the mfg over fuse at the panel and put 15amp fuses in the panel.
the wire AND fuse should match the purpose of a 12v power circuit, whether it be a fan, an inverter or some other 12v device and fused correctly , but each 12v appliance should have a fuse that is correct for that appliance.
i'm not saying run 16ga wire and 15 amp fuses.. i did not say anything like that, and i have never see a light fixture with a fuse, and the fixture will burn before the 20amp fuse on 12ga wire blows out.
separate 12v lighting, from 12v appliance power, water pump, power poles or 12v cig plugs, inverter attachments, ventilation fans
fuse the wire and the appliance
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GDEtrailer: you missed the point!
You do not use single strand wire for 120 volt wiring. Don't confuse this with stranded wire or solid wire.
Single strand wire is used in conduit which provides protection like the out sheath of type NM cable.
You might be mis-understanding MrWizard's post - Sure, if the manufacturer finds "economy of scale" using 14 ga wire, they certainly can go to a higher gauge - BUT, they could also benefit from a lessor price for 16 gauge wire as well - they also don't necessarily have to run 600 volt insulation either for 12vdc circuits - He's also advocating protecting the conductor in his statement above - basically, he is simply saying if you drop to lighter gauge conductor from a "stronger branch," simply launch with a proper fuse - many times in vehicles, a much large conductor feeds a smaller branch, but thru a properly sized fuse
He's not saying anything that merits your expounding to this degree
I had a very good outcome for my DIY van electrical system. More of my newbie questions were answered here than anywhere else.
Many van conversions use a "whole house" approach to the inverter circuit. (An exception to this might be for a separate air conditioner circuit since its too large a load for most inverters.) This means you won't need a separate inverter subpanel.
If you can afford it, life is simple with a Prosine 2.0. It's an integrated 2000w psw inverter/charger with display panel and plenty of smarts for fast charging and automatic switchover to shore power. A great help for a mostly boonie like me.
No need for a converter if you have an inverter/charger.
My efficient Engel 65 accounts for about 2/3 of my watt-hrs. I need about half a kw-hr a day running lights, stereo, limited microwave and induction cooktop, and sundry small electronics. Four agms (420 ah) give me about four days to the half-discharge point. I have a eu2000i gen for backup power but am delighted that I don't need it for the large majority of our pretty mobile camping.
If you have a large bank to support a dc fridge then you also have enough to run a large inverter for useful things like a microwave. My design goal was 2000w to give me the ability to plug in anything designed for a stick-house wall outlet. Tools, hair dryers, etc, as needed. Thirsty consumer devices often assume a 15a source.
We rarely have shore power. The large majority of our kw-hrs come from the alternator. An oversize bank is always nice since it'll accept a kw-hr much faster than a smaller bank that has to taper off. Always quicker to fill a bank to 80% than 100%. I'd also assume some degradation over time---it seemed best to have some extra margin.
I upgraded my alternator from 90a to 150a. Some inferior alternators may die early if the duty cycle is too heavy. The 150a size is common to a lot of commercial conversions.
A SurePower iso/combiner switch with an emergency combiner switch has been useful. Smart switches like that are great since they refill the starting battery first and don't have a diode voltage drop.
I got a lot of marine electrical stuff at West Marine since I thought the boat parts were generally better quality than rv parts. I did not like the yacht crowd prices---but one day I came in with a page full of parts priced on the Web and the manager agreed to match the prices on all of them! Catastrophic fuses and holders, lots of Blue Sea ac circuit breakers and dc fused switches, battery cutoff switch, dc power outlets, marine shore power connector et al. I did use expensive stranded wire instead of Romex and always heavy enough to anticipate slightly heavier loads than the minimum. Didn't want to do it again,
Home Depot had inexpensive 10' plastic wire chases and I liked them a lot. I ran separate chases for ac, dc, stereo wires. My walls got foamed around the chases.
You can't have too many power points. I put in duplex ac and dc outlets at four places in the cargo area and a separate ac power strip to the cab since lots of rechargeables seem to live up front. The ac duplex outlets were from an rv store and they actually clamped down to the ply panels quite well.
Good luck with your project. We have had a wonderful time with a good design forged from these helpful people.
Dan
Dan
02 Freightliner Sprinter 2500 long tall home brew conversion
enblethen writes "GDEtrailer: you missed the point!
You do not use single strand wire for 120 volt wiring. Don't confuse this with stranded wire or solid wire.
Single strand wire is used in conduit which provides protection like the out sheath of type NM cable. "
You and I know what single strand means, but you need to keep in mind that not everyone here understands electrician ease. When posting info it is more helpful to know and understand the broader audience may easily mistake single strand as solid wire. Therefore they may be hunting for a needle in the haystack so to speak.
It is all about being able to take a approach of taking your vast knowledge and wealth of technospeak and break it down to easier portions that the broader audience can understand.
By the way, there is nothing wrong with using single strand in a RV for 120V as long as you provide proper conduit protection. Sometimes this is better than using Romex. Especially considering the harsh enviroment of a van (think of chaffing against sheet metal, Romex won't last long against sharp metal). Flex conduit is a very nice application in this enviroment.
I actually used single strand (in stranded conductor) building wire for all of my 12V circuits for my TT rebuild. This IS the way all RV manufacturers wire with one exception, they do not use wire rated at 600V (RV manufacturers use low voltage rated wire for 12V).
The thing about that unless you want to mail order the wire you will end up paying many times the price of building wire for lower voltage wire you can buy at auto parts stores. Yep, I priced it, at the time I was wiring my TT a 25' piece of low voltage wire at a local auto parts store sold for about the same as a 500' spool of 600V rated single strand wire (in retail, bulk purchasing is a good thing).
For all of my lighting circuits I ran 12Ga (fused at 15A since I didn't put many lights on the circuit and I didn't have 20A fuses on hand when I was tying in the circuits). For my furnace I ran 8 gauge stranded even though the furnace only has a 10A draw, I wanted to ensure the furnace voltage would not sag when running (RV furnaces will shut down if voltage drops too low).
I kept it simple and much lower cost by not buying a bunch of different sizes of wire. And the nice thing was the fact when I was done with my rebuild I could use up any remaining wire around my home or in my garage (can't figure out where you could use 16ga wire for electric wiring other than for speakers in my garage).
Over all I have the most robust 12V electrical system that you could never afford if a RV manufacturer would actually build it my way. I can turn lights on and none dim. I can turn the bath fan on and the lights don't dim (my first rebuild I made the mistake of not scrapping the OEM 12V wiring, turn on the bath fan and the lights dimmed).
It is all about being practical in procuring as much material locally without having to pay high shipping costs or buying more than you need. All electrical (120V and 12V) wiring can be easily found at local stores like Home Depot or Lowes. This is the main advantage of using home building wire rated 600V for 12V applications.
The small amount of overkill in my 12V system is more than worth it.
This is why I state to do it right the first time, basically don't make the same mistakes that the RV manufacturers make by cheaping out on the wire. In a Van the cost difference will only be a few pennies more for heavier wire since the runs will be shorter than say a 26ft TT like mine.
I agree that the 12 volt DC wiring should be stranded and should be thicker than required for minimum voltage drop for when heavier draw item are inevitably put on said circuit(s). It is easier to oversize during the build then it is as an after thought.
I put some serious thought into wiring a hardwired AC system. The Op asked about adding an AC system to a VAN, not a Full sized class A or anything Bigger.
Everything should be protected, but the 120 volt AC system in a small Van need not be huge, with 12/3 Romex running to each corner via circuit breakers through a household circuit breaker box.
I decided that My AC system could be handled by plugging all AC items into a single quality power strip, and said AC power strip hooked to the grid over a quality 12 awg extension cord to the grid.
If I need to run a 120 AC Item from my batteries I disconnect it from my power strip, and plug it directly into my inverter. Then turn in the Inverter.
Things I always leave connected to the power strip are the AC plug to my AC/DC compressor Fridge, and My laptop Power Supply and my Schumacher Smart charger. I could plug the power strip into the Inverter but items that are able to run on DC power without inverting, should be. And there is no point in using battery power to power the inverter to charge the batteries. If there were, then there would also be no energy crisis.
If I choose to run off of available grid AC power, my fridge turns over automatically, and I plug my laptop into the AC Supply line instead of the Dc to DC converter I regularly use.
If there is any other Item I can run on 120 volts AC, when available, I then plug that item into my power strip.
It is my opinion and advice, that for a Small DIY Camper Van, Learn how to, and wire (oversized) your Van for 12 volts DC. When You have 120 volt AC grid power available, distribute said AC electricity through systems as you might at home in a room without enough available outlets. A power surge strip plugged into a quality extension cord. It has it's own overload breaker.
When you need to run some AC items off of battery power when away from grid power, unplug them from the power strip and plug them directly into the inverter.
This is simple and safe. If the power strip cannot handle the amps, it trips. No damage to the wires or devices/ appliances. But I don't run an A/C through mine, But I have run a 15 amp table saw and a (25 amp DC) battery charger at the same time through it.
No Fires, and have never even tripped the power strip's breaker.
In a small DIY Class B there is only a slight aesthetic advantage of having 120 volt AC plugs in every corner or every 2 feet. If that is not important to you, avoid going through the trouble of wiring it up to do so.
* This post was
edited 10/21/09 02:44am by landyacht318 *
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