Wiring through floor vs walls/ceiling

[tomrasdf]

Anyone ever run their conduit through their floors vs walls?

I'm working with a homebuilder to help GC our build, and he's recommending that electrical be run through channels in the floor, both fore/aft from the box and port/starboard where we need to cross over.

I've never seen this done on anyone else's build, and had implicitly implicit assumed that everything (wires/water) would be run through the walls and ceiling.

Any opinions/thoughts on having things run through the floor?

[ewo1]

Originally Posted by tomrasdf

Anyone ever run their conduit through their floors vs walls?

I'm working with a homebuilder to help GC our build, and he's recommending that electrical be run through channels in the floor, both fore/aft from the box and port/starboard where we need to cross over.

I've never seen this done on anyone else's build, and had implicitly implicit assumed that everything (wires/water) would be run through the walls and ceiling.

Any opinions/thoughts on having things run through the floor?

Your gonna have to fish tape alot of wiring not to mention you will need to utilize some good bushing/connectors wherever those wires make contact on any sharp metal edges so they don't fray and short out.

Did he give you a more concise reason on why he prefers to do it that way versus running conduit inside the walls?

[KeyWestPirate]

What wiring system does everyone generally use? Is the bus chassis used as a universal ground? That would permit 2 wire without ground Romex.


What lighting systems does everyone use? LED for sure, but, beyond that ?


(I just know that someone is going to post a pic of a chandelier over his queen bed)

[Phantom5824]

tomrasdf,

I may do exactly this as I am an electrician by trade.

Conduit is usually installed as a complete system before pulling any conductors into it. This requires a complete plan before starting, but then, most good wiring does. In any case, get the wiring plan in place as early in the build as possible, as would be done in a house. Don't make the mistake of believing that 'you'll figure it out later'.
If you do plan to 'figure it out later', run larger conduits - just sayin'


Rich

[tomrasdf]

Originally Posted by Phantom5824

tomrasdf,

I may do exactly this as I am an electrician by trade.

Rich

Rich - what considerations are pushing you toward running conduit through the floor rather than walls, e.g. running along the top of the windows where it would be more accessible than under the floor

Responding to ewo1, he made it seem like that was just how it was done (i.e., running conduit between the joists under the floor). I'm trying to discern whether this is a case of loss-in-translation between skoolie and traditional construction, or whether there are strong reasons for going floor vs walls

[DeMac]

If using a properly installed raceway for one lonely termination point or a homerun trunk-line, it may make sense. The wire ampacity (ability to carry current) may also be derated the due to exterior temps. For most lighting & recepticals curcuits, there's no reason to add the labor and expense.

Exposed & exterior wireruns shall be inside of conduit, which has been properly secured.
What type of conduit & wire is your "GC" suggesting? Rigid, PVC, or EMT? Romex is NOT approved for use outdoors, nor exposed, nor inside of conduit. Must use a wire type listed for exterior use thhn, thhw, xhhw, thwn, etc. (sold by the roll)

Do you intend to use the same wire methods and materials throughout the inside & outside or change over when you pass through? Multiple bulk product purchases (expenses) and more leftover material. (waste).

Nope. No cost or efficiency gains by traversing the exterior of the chassis. Just different than the best ways.

Channels, rails, & chassis are not UL listed electrical conduit. Use MC (indoors) or other protected wire method. Unsecured & unarmored wire inside of the rails of the chassis and frame contradicts all of the approved and listed methods to which licensed Electricians are bound.

[tomrasdf]

Originally Posted by DeMac

If using a properly installed raceway for one lonely termination point or a homerun trunk-line, it may make sense.

My GC's intent was a raceway run inside the chassis, but beneath the flooring. No intent of running anything exterior.

[DeMac]

Originally Posted by tomrasdf

My GC's intent was a raceway run inside the chassis, but beneath the flooring. No intent of running anything exterior.

So your chassis is inside of the bus?
Under the floor is inside?
What does "Inside" mean?

Interior/Exterior of what?
Do you really believe the NFPA considers any part of your bus to be the "interior" of a structure? Interesting....

[KeyWestPirate]

What exterior wiring would we be talking about? I understand the necessity of protecting wire from vibration and sharp edges. The only wire on the exterior I can think of is from the solar panels ?


Anything under the bus should probably be in EMT

[DeMac]

In what chapter of the NEC is the vibrating chassis? Exterior is defined in Article 100, Definitions, also look up Exposed and Damp Locations. Article 3 lists the options for wire methods & materials.

Sounds like you have it all figured out. Nothing for me to help you with, good luck. The pics below are for those who'd choose a better way.

New readers may want to follow some other builder's electrical advise. Just for the safety of shoeless pets & kids.


(1/2" hole saw, undersize first hole)


(half-inch: trade name, 13/16": actual)


(oil-ream to 13/16", for a tight fit)


(insert snap-in bushing)


(properly secured, unreachable by framing nails/screws)


(no metal conduction)

Steel boxes with Steel armor MC (no Aluminum), protected from any possible damage, heat or fire. Unaccessable to intrusion.

How could Romex under the bus be safer? Cheap & inexperienced, yes. Conduit & thhn, okay, buy exposed. Neither are in a safer installation nor easier for the installer. Are you gonna crouch down under there all week and srew overhead, into a dirty chassis? You need a plan.

[KeyWestPirate]

Nice work. But it's highly unlikely I will ever pull a permit or have to pass an inspection.


I'm tall, want to maximize head room. That armored cable would look nice in the basement.

[DeMac]

Originally Posted by KeyWestPirate

Nice work. But it's highly unlikely I will ever pull a permit or have to pass an inspection.

I'm tall, want to maximize head room. That armored cable would look nice in the basement.

Some skoolies chose to convert a bus rather than buy an RV, so that they may build a better rig. Not to avoid the NRVIA, (National RV Inspectors Association). And you can't get a building permit on a bus, silly.

QA is good. But nothing that I do in life is done because someone is going to come behind me and verify that I've completed my task correctly. Integrity solves that.

We chose a bus with 6'6" ceilings to tackle the height limitations while allowing plenty of DowFrothPak insulation.

I guess there was no question in your posts nor answers to the OP's questions. You've got this, KWP. Please post pics of your efforts.

(Edit:
Readers ought to consider following Jolly Roger's Electrical installations. Thorough plans using a variety products, as listed & intended to be used. Safe. Secure. Redundant.)

[Jolly Roger bus 223]

in my first bus everything was ran in the exterior walls that are furred out for insulation and partition walls and ceilings to get to its termination points.
my wifes shorty ended up to be tougher so i had to get creatives and run some in the walls some in the insulated floor in raceways/pvc conduit and some underneath in pvc conduit.
the only wall in the entire layout is behind the drivers seat and it filled up real quick with backup camera wiring trailer connector wiring and the existing bus wiring
i did run 4 seperate back up cameras one on each side for blind spot turn one up high on the back to overlook the trailer and one on the bumper to watch the trailer hitch.
plus everything has a spare wire pulled, and then in the raceway above the driver side windows i ran an 1-1/2" conduit into the electrical compartment above the drivers seat all the way to the back and ran all the back up camera wiring in it to give me plenty of access to change cameras and or wiring or add fo whatever else later.
all of my conduit was sized to have plenty of room for more wire if needed even though i already have a spare pulled.
my 12v system is exstensive and my 120v system is minimal.

[Jolly Roger bus 223]

the decision i made for electrical was based off of what i do for a living.
i do commercial/industrial/federal govt HVAC for a living and am able to catch the leftover stuff going to the dumpsters or get it from the company i work for stock directly.
i end up on jobs with no close supply house so i buy stuff out of pocket to keep the jobs running and for reimbursment i just keep up with what i get out of the stock.
except for the scrap sheetmetal? if its in the scrap bin and the measurments or right its mine before it hits the dumpster. but its gotta hit the dump bin before i touch it but our shop guys look after me if i ask them to watch for. but i still want it to touch the scrap bin first

[Veloc]

I love using conduit, for futureproofing. An eventual broken wire only requires that you tie the new wire to the old before pulling it out, or if it's completely broken in two only requires a simple fish tape to replace. No pulling out walls, cutting out insulation, ect, to reach wiring that was attached inside without conduit. It turns what could be an all week job into 15 minutes. I won't pack them full though, needs to be room for heat to escape the wiring without melting anything. I'd rather run 2-3 smaller conduits than one large one.

Something to consider about an under-bus run - you'll have the potential of a temperature differential causing moisture to condense inside the conduit. If both ends under the bus are pointed up, this could result in the conduit filling with water. When running it under the bus, run it at an angle and put an opening on the low end for water to run out. It'll happen.

Mind you, I'm not a professional electrician, so take it for what it's worth.

[DeMac]

Originally Posted by Veloc

I love using conduit, for futureproofing. An eventual broken wire only requires that you tie the new wire to the old before pulling it out, or if it's completely broken in two only requires a simple fish tape to replace. No pulling out walls, cutting out insulation, ect, to reach wiring that was attached inside without conduit. It turns what could be an all week job into 15 minutes. I won't pack them full though, needs to be room for heat to escape the wiring without melting anything. I'd rather run 2-3 smaller conduits than one large one.

Something to consider about an under-bus run - you'll have the potential of a temperature differential causing moisture to condense inside the conduit. If both ends under the bus are pointed up, this could result in the conduit filling with water. When running it under the bus, run it at an angle and put an opening on the low end for water to run out. It'll happen.

Mind you, I'm not a professional electrician, so take it for what it's worth.

--------------------

That's good stuff. Temp differences, derating wire ampacites, spares & oversized on both raceways & conductors. Exceed the bare minimum.

That part about, 'run conduit at an angle & put an opening for water to run out.'
Sort of...

NEC 225.27 Where a raceway enters a building or structure from outside, it shall be sealed. Spare or unused raceways shall also be sealed...

(Use Plumbers Puddy at both ends & airtight fittings to trap the air.)

NEC 314.15 Approved drainage openings not larger than 1/4" shall be permitted to be installed in the field in boxes or conduit bodies listed for use in damp or wet locations

[Veloc]

Originally Posted by DeMac

--------------------

That's good stuff. Temp differences, derating wire ampacites, spares & oversized on both raceways & conductors. Exceed the bare minimum.

That part about, "run conduit at an angle....for water to run out.
No.

NEC 225.27
Where a raceway enters a building or structure from outside, it shall be sealed. Spare or unused raceways shall also be sealed...

[Use Plumbers Puddy at both ends & airtight fittings to trap the air]

Never thought about plumber's putty as a wiring conduit sealant. If it'll keep moist air out, then there wouldn't be any need for a path to drain water from the conduit. I could also see blowing some dry nitrogen through the conduit before sealing both ends, to reduce humidity inside before sealing. It wouldn't need to be pressurized, just replace what's in there then seal both ends.

[Phantom5824]

Nice looking work DeMac
Your observations are spot-on. Thorough plans are a must.

I plan to use emt, and greenfield as needed, to house type MT conductors for cabin circuits. Anything that exits the conditioned spaces will likely be done in sealtite or marine triplex.


Rich

[Phantom5824]

tomsradf
I will use conduit and greenfield because it's what I do. I like fitting conduit, it protects the conductors well, and it can be re-entered if modifications are desired. All of my conduit will be concealed by finish, and will always remain accessible at each outlet or pull box.


Rich

[DeMac]

We used emt and pvc on our rig, as well. In their best served locations. I believe that electrical theory & application can be well overthought by those who do not have to make these choices on a daily basis. We quickly decide the requirements for the job at hand, then move on with our day to the next one. Ever changing. Inside of a beer cooler, or dog kennel, or surgical room, or hazmat station, or explosion proof room. The proper material for the space, not one size fits all. Each step, every little part, calculation and specification has a function, a special purpose.

Not every aspect of the wirestructure needs to be expensive and complex. Choose the best match for the application. Marine grade wire, open to the air, unprotected, unsecured and in plain view is not impressive.

There are many revolving myths amongst "Skoolie Electricians". Some are more counterproductive than beneficial. Much is simply confusion of one fact for another application, ie. ac vs dc, grounded/grounding/bonded, listed for use, etc. philosophizing & justifying all the way.