John Sayers' Recording Studio Design Forum Archive

Hi guys:

I'm wiring up 5 room studio in my basement that John
Sayers did the design on. I'm in the Kansas City, Kansas
area

I've been reading through the star grounding threads and
have come up with what I think is a slightly easier
way to accomplish this

first, I'm using plastic boxes, and pulling wire through
wood studs. also the outlet plates will be plastic, so
the IG & safety ground will be one & the same

there's two ways folks are doing this best I can tell

1) pull a home runs of 3 wire ROMEX to each and every outlet
black for hot, white for neutral, and bare ground as your
isolated ground

2) daisy chain 3 wire ROMEX to multiply outlets, don't use
the bare ground. separately pull individual THHN green cable,
one for each outlet. depending on the local codes the THHN
can either be bundled with the romex, or might need to
be run in conduit. For safety, the grounds must be run
with the associated conductors

OK, so here's my hybrid approach, I've got 30 outles
so the idea of using method #1, and pulling 30 separate
pieces of romex didn't seem very attractive, not to mention
that you'd need 30 breakers back at the panel for each home
run. Method #2 still has you pulling lots of THHN cable, along
with romex, so it also seemed like a bit of a pain.

so the alternate method allows three outlets per run. we
will use 14-4G ROMEX, which has a black, white, red, blue,
and a bare ground. First, we'll run 14-4G from the panel
to the first outlet. Here we'll wire up the hot & neutral and
use the bare ground. for the run between the 1st and
2nd outlet we'll again use 14-4G, but won't use the bare
ground. For the 2nd outlet we'll use the blue for ground. For
the run from the 2nd to 3rd outlet, we'll step down to 14-3G ROMEX
which has black, white, red, & bare ground. Again we won't
use the bare ground, instead well use the insulated red

The red & blue ground wires will need to be recoded with
green electrical tape at all exposed ends

using the one bare ground wire for the first box. should be no
problem, as the other grounds that will be wired through that
1st box will all be insulated.

to me this seem lots easier than pullling all the individual THHN
cable. It also keeps all the wire in the jacket, which makes for
cleaner connections back at the panel, compared to
Method #2 which has all the loose THHN cables coming back
to the panel. In the case where your not using conduit,
I'm not sure there is an approved way to enter the panel
with all the loose THHN cable.

The 14-4G cable is not to hard to find, Although, typical home
center won't have it on the shelf. I found it in Kansas City
at an electrical supply house without much trouble. Cost for
the 14-4G was $99 for a 250' roll

Let me know what you guys think, I'm headed over to the
supply house to pick up the 14-4G ROMEX and will start
wiring later today

thanks!


Warren

Interesting idea

The first thing that runs through my mind is if it will met code requirements, with the appropriate conductor identifiation of course.

Andre

I would check w/ your local codes before pulling any wire. This may not be an acceptable practice, although it makes since as far as concept.

It may also cost more $$$ doing what you're suggesting.

You could install a large conduit (minimum 3/4", maybe a one inch), and you can do similar to a central point for the wires, then break them out to half inch conduit to go to your individual outlets. If you need a better idea of this, give me a little time, and I'll draw something up.

Also, if you're running conduit, you'll probably want metal boxes. Also, you can check my thread w/ pictures on conduit runs...

Start here, and go through the pix... http://www.johnlsayers.com/phpBB2/viewt ... &start=135

thanks for the feedback

I can't think why this would not meet code, we just
happen to have some extra ground wires in there. I
don't have any inspection to deal with, so safety is
the primary concern

I have a home wiring book that shows as an example
using 14/3G romex with an IGR receptacle. They tied
the bare ground to the frame of the IGR, and the
red (recoded for green for ground) to the isolated
ground. pretty much the same idea just extended
to cover multiple outlets. Since I have plastic boxes
there's no need for IGR's, and hence only one ground

In the threads I was reading, one guy in Colrado got
tripped up by the inspector when he ran individual THHN
wires for the grounds and cable tied them to the ROMEX.
The inspector said that THHN can not be run unprotected
in the studs. The inspector made the guy go back and
put the THHN in FMC. I guess that's good for protection,
and would give you a clean way to enter the panel, on
the other hand it seems like a dumb idea from the
standpoint of "mutual inductance" (correct term??)
where the grounds being in the same proximity
as the hot and neutral help to trip the breaker.
It seems like putting the grounds in FMC would preclude
that even if they are run next to each other.

Others in the forums have said that in there areas they
are allowed to run THHN wire for grounds outside conduit
bundled to the romex

The relevant code issues as I see them are

1) are the ground conductors run with the associated
hot & nuetral ---- YES

2) are all wires inside a protective casing --- YES

3) non-green ground wires must be recoded green --- YES


am I missing anything here?

thanks for the help!


Warren

The relevant code issues as I see them are

1) are the ground conductors run with the associated
hot & nuetral ---- YES

2) are all wires inside a protective casing --- YES

3) non-green ground wires must be recoded green --- YES


am I missing anything here?

Nope.


Now, here's another option...you can tie hot and neutral to multiple outlets, just be sure to have a "Home Run" for the ground for each outlet.

yes, daisy chaining the hot and neutral across
the three outlets in the run is the key to this
method. This is the only way you can have enough
wire when using 12-4G romex to handle the isolated
grounds for three outlets

black - hot for all three outlets
white - neutral for all three outlets
bare copper - ground for first outlet in the run
blue - ground for 2nd outlet in the run
red - ground for 3rd outlet in the run

also using the bare copper in the first box keeps it
away from anything that could screw up the
isolated ground scheme


another key is that you can drop down to
12-3G between the 2nd & 3rd outlet


thanks again for the input


bye the way Aaron, I looked your thread from
the link above. Wow! I'm gonna need to spend
some time there.... looks like you covered quite
a bit of things I'll running into!

Warren