Horizontal Branch Circuit Vs Vertical Branch Circuit

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kyleapec

kyleapec

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siloam springs arkansas
The job specs on my project state:
E. Horizontal Branch Circuits: Type THHN/THWN, in raceway.
F. Vertical Branch Circuits: Type THNN/THWW in raceway or Type MC Cable

My first assertion, off of the bat, is horizontal is between boxes (daisy chaining receps), and vertical is up out of the wall to a JB above an accessible ceiling. If that is true I would think the vertical (up into the ceiling) is where they would want emt, and horizontal is where they wouldn't mind MC Cable. I have never seen this before.

(I am in the process of sending an RFI through the chain but i wanted a second opinion.)

I apologize if I was vague, my question is "What is a vertical branch circuit and what is a horizontal branch circuit".
 
to me, "branch ckt" is confusing the requirement because many BC's have to run hori and verti to get where they need to go.

horizontal spans, as spec'd (wire type in raceway)
vertical spans, as spec'd (wire type in raceway, or MC cable)

it seems that is what the job is calling for.

why two types of wire? dunno. if the wire type that is in MC not the same as the spec'd type for raceway, does that matter?

THNN/THWW ?? if you didnt do MC on vertical i would request acceptance to use THWN-2 for everything.
 
I'm as baffled as your are. My first thought was fixture whips, but that seems to be horizontal.

I have spec'ed jobs where its conduit back to the panel so we don't have 42 MC cables all roped back to a panelboard. That would look pretty ugly back at the panel.

But to save costs we allowed MC after the first outlet or receptacle. That usually lets someone add a wire or an extra circuit without requiring a new conduit run all the way back to the panel. That makes change orders more reasonable.

Let us know what you find out.
 
i guess like roads, if the total distance run more hori than verti, its a hori run. if the total distance run more verti than hori, its a verti run ??
 
jumper said:
New stuff from China.:D
Click to expand...

If you Google it you'll find a bunch of specs calling for it. They all seem to be for hotel/motel jobs. Looks like someone cribbed it and everyone else copied along.
 
K8MHZ said:
Probably a typo, or an intentional error to spot plagiarism.

I don't think there is such a thing as THNN or THWW.

NN would mean 'nylon jacket, nylon jacket', and WW would mean 'wet location, wet location'.
Click to expand...

I would say typo.

Someone wrote a set of specs and people are just cutting and pasting as gadfly stated.

If I was ambitious I could prolly find the original paper using this:

SECTION 26 05 19 (16120) - LOW-VOLTAGE ELECTRICAL POWER CONDUCTORS AND CABLES

It shows up pretty consistently.
 
jumper said:
I would say typo.

Someone wrote a set of specs and people are just cutting and pasting as gadfly stated.

If I was ambitious I could prolly find the original paper using this:

SECTION 26 05 19 (16120) - LOW-VOLTAGE ELECTRICAL POWER CONDUCTORS AND CABLES

It shows up pretty consistently.
Click to expand...

It looks like it was written with Masterspec software. I would guess the typo is in their database.

So somewhere, Masterspec should define what they mean by horizontal or vertical branch circuits.

I wonder if there are some engineers that leave that language in their project specs even though they don't know the difference.
 
steve66 said:
It looks like it was written with Masterspec software. I would guess the typo is in their database.

So somewhere, Masterspec should define what they mean by horizontal or vertical branch circuits.

I wonder if there are some engineers that leave that language in their project specs even though they don't know the difference.
Click to expand...

We have MasterSpec and I looked up the section quoted in post #9 by jumper. This vertical/horizontal differentiation is definitely someone's internal standard spec. The MasterSpec sections are 3.1, 3.2, etc, not 3.01, 3.02, etc and do not differentiate by orientation.
 
i think its this.
vertical and horizontal as you know it. anything running vertical (i assume more up/down then left right) you have option to use MC, everything else is conduit, and thwn-2 should suffice as it meets/exceeds what was spec'd. i cant think of a reason why using thwn-2 would be an issue.
 
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