Electrical - adding AC wiring to 12 volt system

[honda03842]

Joe I'll take the one in our picture apart to show more detail, off to a party now. I did not use a box for the four boxes mounted in fiberglass. Scamp does use boxes. They rivet their's. I simply,cut a hole, wired the outlet, wrapped the outlet in electrical tape and screwed it to the fiberglass. Outlets that can't be seen like for the ater heater, convertor and fridge all have traditional plastic outlet boxes.

[steve dunham]

Standard circuit breakers do not come in a 10 amp rating. Since the smallest AWG wire size allowed in building construction for branch circuits is #14 rated for 15 amps ,the smallest standard breaker is 15 amp .2) Box size is determined by cu inch capacity ,wire size and number of devices installed in the box . Each # 12 AWG conductor requires 2.5 cu inches of capacity , the receptacle counts as 2 conductors and if the box has internal cable clamps that counts as one additional conductor . If you run a single 12-2 romex into a box with clamps and install a receptacle in that box you will need a box with a minimum cu inch capacity of 15 cu inches . There must also be 6" of free conductor at each box .Using boxes that are two small forces you to cut the wires extremely short and force the outlet into the box which leads to numerous other problems . Installing a GFCI receptacle is next to impossible in a shallow box. A 100 amp circuit breaker panel is rated for 20 branch circuit breakers with a maximum of 24 breakers so if you need more space for breakers you need to get a bigger panel (150 or 200 amp) The main breaker (service size) in a service panel is sized by the calculated load based on tables in the NEC not by the number and size of the branch circuit breaker ratings .Standard NM cable (romex) does not come in stranded wire only solid .They manufacture cut in boxes in both metal , plastic and fiberglass . If you use plastic or fiberglass boxes you must be extremely careful to cut the holes in the trailer really close or the plate will not cover . If you wanted to place every receptacle in your trailer on a separate 20 amp circuit ,you would not be violating the code but at some point the cost does not justify the extra work for little gain . Many appliances that have a small amp draw and the branch circuit breaker does not provide adequate protection come with a built in over current device . Look at your garbage disposal and there will be a red button on the bottom (internal circuit breaker) which provides running over current protection for the disposal motor

[Cat futrell]

Tom,

What kind of box? We don't have studs, are there special boxes for rv that will mount flush? All of our outlets are in fiberglass. If there are I haven't been able to find them. Maybe I am searching with the wrong name. Can't find 30 amp AC distribution panel with room for 6 sub breakers.

[Cat futrell]

Steve,

We were talking about the boxes that enclose en electrical 110 outlet. (With plugs). However I think that you may have posted information pertaining to my last post.

[Cat futrell]

Steve, after retreading your post I realize that some of your post does relate to my question about outlet boxes. I don't know correct terminology so am learning as I go. Is the box with the circuit breakers the distribution box? And the circuit breakers called sub breakers, the main breaker in the distribution is 30 amps?

[steve dunham]

Originally Posted by honda03842

Joe I'll take the one in our picture apart to show more detail, off to a party now. I did not use a box for the four boxes mounted in fiberglass. Scamp does use boxes. They rivet their's. I simply,cut a hole, wired the outlet, wrapped the outlet in electrical tape and screwed it to the fiberglass. Outlets that can't be seen like for the ater heater, convertor and fridge all have traditional plastic outlet boxes.

The NEC requires a box at EVERY outlet location The purpose of the enclosure (box) is to prevent accidental contact with energized parts and to contain the arc in case of the device faulting. Tape is not an approved barrier and has no arc rating .All outlet boxes are fire/arc rated . Example Plastic boxes are not approved for use in a 1 hr fire rated wall . Additionally if you look at an outlet box all the holes in the box are small so the arc is contained and if you punch out a KO and do not use the hole you must seal the hole with a kO seal with a fire rating equal or greater than the box rating Again tape is neither legal or safe Many of the cheap electrical tapes available are not UL listed and will fuel a fire when exposed to an electrical arc

[Cat futrell]

Steve,

What would you do? You are hereby released from any liability because of any answers or information that you will offer.
We have a 13 foot Boler type fiberglass camper with the standard inside configuration. All of our 12 volt wires are run and we have a PD9245, progressive dynamics 45 amp converter. I have some mobility issues so for the sake of convenience (since we want to add the AC) we want to install;

5 ac outlets.

2 on the driver's side at the front of the galley. One of those will be on it's own circuit because it will power the converter.
1 on the driver's side rear of the galley.
1 on the passenger side rear of the galley
1 on the outside of the camper on the passenger side.

How would you do it. 10 gauge stranded wire has been planned for the circuit from the 15 amp sub breaker to the the outlet supplying power to the converter.

At this point we can completely start over except for the dc wiring.

[Cat futrell]

Steve,

Thank you, I am not comfortable with the electrical tape idea. We had planned to use 12 gauge stranded wire for our outlet circuits. Did you say that there are fiberglass boxes? We have an electrician friend who is suposed to come over sometime this week to check on us but he knows nothing about rv or marine supplies and available materials.

[Thomas G.]

Originally Posted by Cat futrell

Tom,

What kind of box? We don't have studs, are there special boxes for rv that will mount flush? All of our outlets are in fiberglass. If there are I haven't been able to find them. Maybe I am searching with the wrong name. Can't find 30 amp AC distribution panel with room for 6 sub breakers.

Originally Posted by Cat futrell

Steve,

Thank you, I am not comfortable with the electrical tape idea. We had planned to use 12 gauge stranded wire for our outlet circuits. Did you say that there are fiberglass boxes? We have an electrician friend who is supposed to come over sometime this week to check on us but he knows nothing about rv or marine supplies and available materials.

There are boxes designed to be installed in a rectangular hole in the wall. As mentioned, you need to carefully cut the hole so it just fits. The box has wings that pivot out and grab the back side of the fiberglass, holding the box securely. You then wire in the outlets. If some outlet boxes are too small for a GFCI outlet, you can wire the GFCI outlet in a larger box (where it fits) then feed the smaller outlet box from the GFCI box, protecting the second non-GFCI outlet in the process.

[Roy in TO]

Cat,
You are overdesigning everything. 6 separate 15 or 20 Amp AC circuits in a 13' trailer is overkill. I don't think I could find room for 6 outlets alone in mine. Remember, most appliances come with at least a 3' cord. That power post (current bush as Alf calls it) you are plugging into usually has at least 2 outlets if not more. Carry an extra extension cord for those rare times of need. The way I see it, by the time you load your trailer with that many electrical appliances to fit into 6 circuits you are not going to have any room for yourself.

As suggested before, you have to figure out what your power needs are going to be and when you are going to need it. Designing for the minimal means you can camp on a single 15 Amp connection when needed and be luxurious when you have access to a 30 amp. Like someone said before you won't use the heater and A/C at the same time. You can turn the A/C off for a few minutes while you make coffee or microwave popcorn. And so on.

If any of your outlets are going to be external, here is something that does not need a box. A little pricey but nice. Product Datasheet -- HBL61CM65

[steve dunham]

Originally Posted by Cat futrell

Steve,

Thank you, I am not comfortable with the electrical tape idea. We had planned to use 12 gauge stranded wire for our outlet circuits. Did you say that there are fiberglass boxes? We have an electrician friend who is suposed to come over sometime this week to check on us but he knows nothing about rv or marine supplies and available materials.

Allied manufacturing makes a fiberglass box but it comes in a beige color only. You can not legally run individual wire to feed your outlets. You must use a UL listed cable such as NM or UF . Single conductors need to be installed in a raceway such as rigid conduit ,emt ,greenfield , nonmetalic flexible conduit Etc. . 12-2 romex is the way to go cheaper ,easier to install and conceal . Any time the cable enters a box or enclosure an approved connector or cable clamp is required . I use T&B #3201 or #3300 blue plastic romex connectors --Less chance of the cable shorting than with the metal 2 screw connectors If you use metal boxes be sure to properly bond the box

[steve dunham]

Originally Posted by Cat futrell

Steve,

What would you do? You are hereby released from any liability because of any answers or information that you will offer.
We have a 13 foot Boler type fiberglass camper with the standard inside configuration. All of our 12 volt wires are run and we have a PD9245, progressive dynamics 45 amp converter. I have some mobility issues so for the sake of convenience (since we want to add the AC) we want to install;

5 ac outlets.

2 on the driver's side at the front of the galley. One of those will be on it's own circuit because it will power the converter.
1 on the driver's side rear of the galley.
1 on the passenger side rear of the galley
1 on the outside of the camper on the passenger side.

How would you do it. 10 gauge stranded wire has been planned for the circuit from the 15 amp sub breaker to the the outlet supplying power to the converter.

At this point we can completely start over except for the dc wiring.

1)10 gauge wire is legal but not necessary 12-2 romex is more than sufficient 2) If you were to use #10 you would need larger boxes (3.0 cu in per conductor) 3)Stranded wire should be attached to the device with Stakon crimp connectors - wrapping stranded wire around the device screw is POOR practice

My trailer (All wiring in 12-2 MN

!) Kitchen outlet on separate 20 amp circuit
2) Outside GFCI outlet on separate 20 amp circuit
3) Water heater on separate circuit
4) Refrigerator & Microwave on separate 15 amp circuit
5) Converter on separate 15 amp circuit
6) General purpose receptacles on separate circuit (TV. chargers vacuuming)
7) A/C separate 20 amp circuit
8) Main 30 amp breaker

[Cat futrell]

Roy,

Thank you for mention those points. We absolutely will not be using every plug at one time. My primary concern is that, no matter which end or side of the camper I am sitting,I have access to AC power. Because of my physical limitations Extension chords and plugging in and unplugging is not practical. It does not seem sensible for us to install AC wiring and not make it the most usable for us. Besides, we may put on an addition after we are done with the current project. NOT! lol

[Cat futrell]

Steve, I see you have a new Casita (sweet). Did you have to change the supply panel or did it come with all of those slots for circuit breakers?

[GPJ]

Cat:

Here are a couple of links which may help you:

1) A typical (if anything is typical) small trailer wiring diagram from the document center. This covers the trailer lighting, 12V and 120V circuits so is more than you need. You can see that the A/C, refrigerators and converter are on their own circuits, while the outlets are all on one circuit. Since you have plenty of circuits and probably not a lot of appliances, you have capacity to put the outlets on a couple of different circuits. There are lots of ways of doing this - ie. you might split it left and right side, you might split it by zones, or you might split it to have "special" items on their own circuit (eg. Ground fault outlet). Someone else please add some criteria if I have left something useful out. Remember, you don't have to use all the 6 circuits - ifyou don't have a fridge now and want to add one later, leave an open circuit for it, similarly, you might want to leave one to hard wire an A/C later, and you might want to leave one open for something you just can't think of right now.
http://www.fiberglassrv.com/forums/d...gram_Scamp.pdf

2) There are some terminology issues in describing outlet boxes. First, you have to have an approved box around each outlet - that is generally metal or plastic. Electrical tape just won't do. Now, its not real clear what you are working with - you don't have studs, and its not clear if you have any wall surfaces (ie. sides of cabinets, interior walls, etc. to mount the floating boxes to. These are self-contained receptacles that are often used in RVs. See these:
Diamond Self Contained White Receptacle - Receptacles - Switches and Receptacles - Electrical
SELF-CONTAINED RECEPTACLE #WDR15IV
But you still need some sort of interior wall surface to mount these to.

3) There are also surface mount receptacles like these ....SELF-CONTAINED RECEPTACLE #WDR15IV

These look a little old fashioned, but there are more modern versions available like these (you just need to add the outlet part)...Leviton 1-Gang White Surface Mount Wiring Box-R14-42777-00W at The Home Depot.

4) Finally, do a search on "surface wiring" to find kits and information for running wiring on wall surfaces through nice covered raceways to attractive boxes. For example...How to Use Wiremold Non-Metallic Raceways to Run Surface Wiring - The Home Depot | The Home Depot

[Cat futrell]

GP,

We do not yet have circuits, for we have no distribution panel "breaker box" yet. I used 6 circuits as an example. I was trying to understand power allotments to separate circuits. Our original intent was to get a breaker box with 2 or 3 circuits. One for the converter and the other to string the outlets together onto one circuit. I do understand now why this is not the best way to do it.

All of the outlet will be installed in fiberglass walls. Galley walls, closet wall, and then one to the exterior. Our camper is a single wall fiberglass.

I have been searching for an RV breaker box since yesterday. The only thing that I am finding are exterior boxes with 1 or 2 circuits and an outlet, and marine supplies.

I have not yet looked at your links but am going to now, hopefully I will find some useful materials.

[Cat futrell]

also,

All of our wiring will be concealed. running it along the outside edge of the floor where it meets the wall. This entire area is covered with galley, benches, and closet. We will use conduit but do not yet know what kind.

[Cat futrell]

GP,

Those self contained outlets look like they will do the trick. We will not be surface mounting, we will recess. The recess will protrude into the inside of cabinet, closet. This is why the low profile is so desirable, as well as the ability to install on a thin wall.

If you could point me to a breaker box (it have to have 6 circuits) of small proportion, I would be ever so grateful.

Thank you for going to the trouble of posting those links.

Cat

[Cat futrell]

It does not have to have 6 circuits

[Thinh]

...Metal or plastic box for electrical outlet is one among safety features. To install such a box in RV or automotive application, there are numerous ways to be applied. Either self-tapped screw, repair rivet, metal clip assisted or just simply drill a small hole in material(smaller size of screw itself) for those sturdy materials, like metal, aluminum or even fiberglass. The following photos are some of those, just my share... for you members...