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Help, wiring in the ceiling ribs

12K views 66 replies 15 participants last post by  MsNomer 
#1 · (Edited)
I have to install wood furring strips on the ceiling ribs to make space for another layer of insulation.
I plan to use self tapping metal screws to hold the the wood strips on the metal rib if that is a good choice?
BUT I will also be running insulation AND wiring in the ceiling ribs.
What keeps the screws that hold the furring strip on the rib from hurting/puncturing/scraping my electrical wires
that run from one side of the van to the other via these ceiling ribs? I know many have installed wood furring strips,
how is everyone attaching them to the ribs?
THANKS!!
 
#2 ·
Buy a Astro Rivnut tool kit, $60 on amazon or ebay. Buy extra rivnuts, at least 50 or 60. They go fast! Greatest tool for doing a van conversation. Self tapping screws will eventually vibrant loose and possibly damage the wire. Practice compressing a few rivnuts first in a bench top type test, if you squeeze hard on the smaller size
(10/24th) it is possible to pull the threads out of the rivet.
 
#3 ·
I have 1 x 4 furring strips run lengthwise fore and aft attached to the ceiling ribs with self drilling/tapping Teks screws. I used 4 of them purchased in long 12 foot lengths. These hold the insulation in place. I ran wires across above the furring strips not in the ribs.
 
#5 ·
If you're running furring strips and insulation why does the wiring have to go through the ribs? Why not add a length of PVC conduit along side the ribs instead?

I've run wiring in ceiling ribs before, but I'm not a big fan of doing so. First of all, it's not exactly easy to feed wire through most of them. There's excess adhesive, sharp edges, 90 degree turns, and all sorts of things that make doing so difficult. It's also metal, so it's a likely place to wear or cut a wire and could result in a short which would then be a very difficult place to repair. The ribs are also needed for securing things later on in the build, and that's not easy to do when there are wires to watch out for. When everything going to be covered in in insulation anyhow, hiding 1/2" PVC underneath would be a breeze.
 
#6 ·
TravelDerby that is a great idea. I could run 1/2 inch pvc from one side of the van to the other adjacent to the rib.
Only thing I'd loose is the very small amount of rigid foam board where the pvc occupies space.
There really are a small number of outlets on the far side of the van. Over there I want 3 AC plug-ins and 3 DC plugins. I don't think that much
will fit into 1 1/2 inch pvc pipe so I could have two pipes making the traverse.

Forgot to add that will make stuffing the Thinsulate into the ribs easier :)
 
#7 ·
PEX Tubing - A PVC alternative

I could run 1/2 inch pvc from one side of the van to the other adjacent to the rib.
We bought a roll of 1/2" PEX tubing (which we'd never heard of prior to this project) to plumb water from point A to B. Turns out, however, that we've used far more of this tubing as a protective conduit for both low and high voltage cabling . . . particularly where we feared shape metal edges. PEX tubing is more flexible than PVC and easily cut with a Stanley knife.
 
#9 ·
What type of 12V wire

Hi MM4040. I'm enjoying following your build and questions, you are about 8 weeks ahead of my build so I'm happy to learn from you. Quick question on low voltage wiring. I have ordered 12 AWG speaker wire for my build. Based on various voltage drop calculations it seems 12 AWG is more than sufficient. My question to you and others is, is speaker wire a good idea? This wire actually has an overwrap, so it looks more like "regular" low voltage wire than speaker wire, at least to me. Here is what I ordered (100ft).

http://www.primecables.com/p-313373...ll-installation-4-lengths-monoprice#sku313373

Thanks
Shaun
 
#11 ·
Hi MM4040. I'm enjoying following your build and questions, you are about 8 weeks ahead of my build so I'm happy to learn from you. Quick question on low voltage wiring. I have ordered 12 AWG speaker wire for my build. Based on various voltage drop calculations it seems 12 AWG is more than sufficient. My question to you and others is, is speaker wire a good idea? This wire actually has an overwrap, so it looks more like "regular" low voltage wire than speaker wire, at least to me. Here is what I ordered (100ft).

http://www.primecables.com/p-313373...ll-installation-4-lengths-monoprice#sku313373

Thanks
Shaun
12 AWG is way overkill for most any 12 vdc circuits will ever run or need. Even !4 is overkill. 16 should suffice for just about any lighting or charging circuit. You might need 12 or 14 for a fridge but that is the exception. I would say I probably used 16 speaker wire for 80% of my DC circuits and a bit of 14 for the rest and I've never ever had a blown fuse or overheated wire. As usual the wire size is dependent on the load you put on it obviously but most 12vdc loads in a van are not very large.
 
#15 ·
ShaunB I'm learning too.
Example, I would never have known or thought to use speaker wire for DC runs.
My electrician said two days ago that we'll go shopping soon. I said to Lowe's, he said
no to a sound shop :)
MsNomer you're not helping ;)
Just went I decided to run my three circuits from the passengers side over in PEX now I'm puzzled again.

One thing I've gathered here is that often there isn't a wrong or right absolute black and white answer.

ShaunB our big day comes tomorrow. The van heads to the man who will cut all the big holes (windows/AC/fan).
When it gets back from him--a week, maybe two--then things will start happening.
In the mean time we're just collecting stuff...it's like a mini-warehouse here, even today the heavy dynomat generic arrived.

It's fun though. It's like I'm learning a new language, def. learning a bit about electricity. I'm also learning that this whole process can be a economically friendly as you want or seriously painful on the wallet. 100 years from now it won't matter and in that I just gave 80/20 $1300 for a giant tinker toy erector set (and I haven't even bought the connectors yet!)....
 
#17 ·
MM you're learning! You don't need conduit as others have suggested but it is very cheap and helps if you ever want to make and later mods, especially over the roof or under your floor after it's finished. I have both bare cables wire tied together in accessible spaces and the blue plastic flexable conduit (make sure you use ¾" conduit if you do, NOT ½") in other places. PEX could also be used and being smooth inside could be a better choice but the blue plastic bx has fittings that allow it to be easily connected to electrical boxes. So many choices ;). I'm sure your Sparky will also advise you.
 
#16 ·
Wiring does not need to be in conduit. It does need to be secured so that it does not move causing chafe. Burying it in insulation can work. Lightly compressing it between finished ceiling panels and insulation works as long as it does not contact sharp edges. It is important to prevent movement. Some years ago an owner on the Sprinter forum claimed that he could hear wires rattling in overhead conduit (conduit was possibly excessively large).

Also on that forum a couple of owners had installed conduit crosswise under insulated floor between the edges of sheets of rigid foam.
 
#19 ·
There is 1/2 and 3/4” smooth and rigid plastic conduit that is PVC. Get it instead of the water pipe and they will think you are a pro. Pull a string through and then use it to pull the wire. First time use a fluff ball and your shop vac to pull in a string. No problem. I pull a string each time I pull a wire so I always have a way to add another. In the van I really did not see much need for conduit but used lots of wire ties to keep everything from moving around. I wish I had not used that romex to the 110 outlets and shore power outlets. Stranded wire!
 
#23 ·
Hi RD,

I did all of my van wiring with solid Romex -- DC and AC circuits.

Had two commercial RV's before this that were done with Romex -- one was a Coachman, a popular and well respected RV manufacturer.

I've seen the idea that solid wire should not be used in an RV due to the vibration, but I looked pretty hard for any actual evidence that it really can be a problem and did not find anything.
Not convinced that there is any problem with solid wire in an RV -- does anyone have any actual cases where use of solid wire caused a failure?

I like the Romex -- easy to run and the outer jacket provides some extra protection against abrasion. Its a consistent product built to a spec.

Gary
 
#20 ·
Yes the blue plastic bx is a real pita it's almost a requirement to use the ¾" stuff the corrugations really make it difficult to pull anything thru after the first wires if you can get short pieces of ¾" smooth pvc go for it. It probably comes in 10' lengths and 50' foot coils . You can easily use up almost 50' in a van!
 
#25 ·
Gary thanks. I've run this by the electrician who will do the connections at the main electrical center after we've finished with the insulation and running the wires.
On the passenger side of the PM we'll have three outlets spaced along the van wall from the sliding door entrance to the rear doors. Each outlet will have ac and dc (the ARB frig uses either as does the BOSS shower). So far the electrician is agreeable with the use of ROMEX for the ac but insists on speaker wire for the dc.
Still undecided on how to cross the van with either but at this point all things considered. We have 1-2 weeks to decide while the roof work and window work is being completed.

In route to us now-
ARB frig
Legend Fleet KK plus floot, panels for walls and ceiling

Ordered but not shipped yet- 80/20 cabinet

All major electrical components are here.

Only big ticket item left besides running boards is the Fiamma Carry bike. At first I thought it way pricey but looked at a normal 3 bike carrier by Thule for hitch mount and they can be pricey too. Just the price to be paid for being able to open the door without removing the bikes.
 
#27 ·
Gary thanks. I've run this by the electrician who will do the connections at the main electrical center after we've finished with the insulation and running the wires.
On the passenger side of the PM we'll have three outlets spaced along the van wall from the sliding door entrance to the rear doors. Each outlet will have ac and dc (the ARB frig uses either as does the BOSS shower). So far the electrician is agreeable with the use of ROMEX for the ac but insists on speaker wire for the dc.
Hi,
Does the electrician give a reason for wanting to use Romex on the AC and speaker wire on the DC?

About the only advantage I can see is that you can look at the wire and know that it is carrying AC or DC just by its appearance? Sort of a standardization thing.

Gary
 
#26 ·
4040,
I ran the unprotected 12-2 wg across the van inside a roof rib. No big deal as there are lots of openings. At the transition to the walls it is a bit challenging.
 
#28 ·
The insulation is the variable, romex meant for residential use is a tough known variable. If you must go w/ romex do not get the 2 wire with the lighter gauge uninsulated ground (its less expensive), get the brand with full size & insulated ground. Solid conductor will do nicely IF it is well anchored, ie. within a few inches of each termination and it does not run through long hidden or no-access areas where it can't be anchored - near-zero movement across every last inch of it is required. That's where getting the marine quality stranded comes in, it will simply lay in the trough it's pulled through without standing proud and quivering like a tuning fork...
 
#29 ·
Zoomyn, me, well I'm good with either or any. Send me a link/url and I'll order up the marine stranded. Please tell me again what size/gauge I need to order.
My electrician is a stick-built type, and we know their mindset, but he'll use what I buy eh, and if I have the
stranded on hand for the AC that's what he'll use I bet.
Unlike my future Webasto install who does NOT like the under passenger seat install.

Gary my electrical guru likes Romex for ac and speaker for dc, true, I can't get across to him that Romex will do for either.
Now Zoomyn has me onto the stranded. Really, I'm good with anything not knowing anything! Seriously big holes were cut into our PM today=progress, and I opened the box for the ARB 50 qt. I think this was way better than just the Artic coolers, so thanks to the forum for that influence.

Ordering the bike rack tonight.
 
#30 ·
Stranded is the best way to go as solid must be secured everyplace because vibration can cause it to crack/break. Here is one reason why household electricians prefer to use solid: Solid wire can be easily bent to fit under the screw terminals on household type switches, outlets, etc. Stranded is best secured to these fixtures by crimping on a spade lug having up-turned ends on the forks. Some electricians are not familiar with this or they do not want to take the extra time to do it correctly.
 
#31 ·
Stranded is best secured to these fixtures by crimping on a spade lug having up-turned ends on the forks. Some electricians are not familiar with this or they do not want to take the extra time to do it correctly.
And then . . . . there's Winston's old ham radio approach - - "tin" (with solder) the stranded wire ends essentially turning the stranded into a solid wire at the point of connection. (Suppose the stranded purest will argue that this defeats to purpose.) We're particularly fond of this approach when faced with those ground interconnect buss bars often found in electrical distribution panels in which wires are retained only by the pressure from and advancing screw. Non-tinned stranded wires tend to 'splay' pushing a percentage of the individual strands outwardly where they are effectively 'not retained'.
 
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#32 ·
Again it is too much information.
Truth is I like Gary's approach, why? Because one can write on each end what/where it goes to!
This can't be that complicated :)
Though I do understand the concept of each approach.

Everything we can think of is now here or in route except the running boards...I called the runningboard warehouse and the ones link elsewhere on this forum were said to not have the correct mounting things for our 136wb....see, it's the little things! I'll probably have all my teeth pulled out by the time we 'erect' the box of goodies from 80/20.net.
All fun though.
And today I got to meat one of the builders of the gentlemen here from Kentucky (sorry name escapes, I've been up 27 hours) who is in Baja and has taken his PM all over n.America. The same installer is putting in our windows/solar/etc.
He too by the way said no to wires in the ribs but yes to wires in PEX beside and zip locked to the ribs :)
He also said the idea of putting the Webasto in front of the passenger wheel well would be find (he's done many Espar installations).....so we'll get there, one day at a time.
 
#33 · (Edited)
Hate being subjected to conductor snobbery myself but if our projects occupied by sleeping people 5, 10, 15 years in the future:

Romex by itself installed by a beer-engineer will probably do famously, it's where the wire has a slight flaw, been knotted, kinked or nicked, spindled over an unseen barrier pulling it or flexed back and forth on itself a dozen or more times when routing or rerouting, and/or where Joe Somewhen CHANGES what we've installed after replacing X, Y or Z for the third time that risks ramp up exponentially in these vehicles that may be in motion 40+ hours a week and then occupied 24/7 by children and drunks... err, senior citizens.

My 1972 & '73 Airstream trailers have/had a hundred-plus pounds of romex installed by six-pack-before-lunch production line drunks without burning but the trailers have a Cadillac ride and usually are in motion only a few days of the year. I also pulled every bit and got $2+ a pound scrap value out of it.

https://www.amazon.com/dp/B000NUYBRK <--- One source of Marine grade cable, I did use the flat style myself. (http://tinyurl.com/jhdp9qa) [[EDIT: changed single strand link to multi-strand] Wow - on test that link was not updated, still shows original, try it again https://www.amazon.com/dp/B000NUYBRK]

http://www.powerstream.com/Wire_Size.htm <-- work the numbers. The only source of free power in the future would be heavying up conductors now. Example: 3+7+12+7+3 feet to go diagonally from corner to corner of my van - 32 feet, say a 10 amp @ 12 volt load... 5.48% drop with 10awg, 8.71% with 12awg, 13.83% with 14awg.

If the voltage drops then the current rises, the wattage draw spec of the load will be satisfied then add the cable losses so think 105.48% @ 10awg, 108.71% @ 12awg, 113.83% @ 14awg. How about 40 minutes free run time of the ceiling vent fan after 8 hours on if we go with 10awg versus 14awg? I ran 10awg from my 12V power center to the galley area, to the roof vent fan, to the possible black tank macerator pump, etc..

Solar feed lines are important - 300w solar at 12V nominal (parallel array) is 18~V to the charge controller so about 17A current. A basic rule is 3% or less drop from source to controls and then 5% to the individual loads from the distribution center. Remember the line size losses start at the solar panel itself when calculating, include the whips through the roof etc... Saving 5% is a free day of sunshine every month!
 
#34 ·
for medicineman4040 and anyone who wants to contact Morehead,
I think the poster is Steve who drives the “backroader” and is at the Southern tip of Baja right now. His conversion was done by Morehead Design Lab, http://www.moreheaddesignlab.com who lists his address as 43 Smith Mill Rd, (Smith Mill Works) Asheville NC, 28806 Video at:
Is that who you meant? Get some sleep!
 
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