Subject: [Shop-talk] Electrical install questions

From: "Steve Hammatt, Mount Vernon WA USA" <[email-masked]>
Date: Fri, 31 Jul 2015 16:15:22 -0700

Need to hook up home central a/c located in my (temporary) shop/garage.
New shop and extra garage space is to be soon added to our property.
The installation will be handled by a local HVAC contractor (using an outside
electrical contractor) or option is to allow the homeowner (me) to supply the
power from the panel to the electrical shutoff mounted on the outside wall
of the garage, next to the condenser.  We have a dedicated 30A 240V circuit,
previously used for an electric clothes dryer (now switched to gas) that
goes up and through the garage attic trusses (above the garagebs drywall
ceiling)
toward the housebs laundry room.  My thought is to interrupt the run to the
dryer, terminating the run toward the no longer being used dryer, and install
a J-box to make a new run to the adjacent garage wall for the a/c unit.  I
plan
to bore through the double top plate and run the Romex down through the wall
and through to the outside where it would be connected to the switch box.
Here are my questions:
1.  Planning 2.5 ton 13SEER unit.  What Romex wiring size can I run?  Itbs
about a
total of 50b.
2.  I understand that the J-box in the attic storage space must be easily
accessible.
Any other placement requirements?
3.  Any recommendations for the outside switch box?  Is there a design for
going through a siding/OSB exterior wall?
4.  Any nailing recommendations?  Ibm familiar with not nailing (staples)
too
tight on the Romex.  Spacing suggestions?
5.  Any other suggestions before we get started?
Home owner electrical is OK here, but I certainly do not want to be anything
less than safe.  The quoted electrical cost for this job (through one of the
a/c contractors) was over $800 which I hope to lessen drastically.
Thanks for your assistance.
Steve

Steve Hammatt
Mount Vernon WA USA
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From: David Scheidt <[email-masked]>
Date: Fri, 31 Jul 2015 22:36:04 -0500

On Fri, Jul 31, 2015 at 6:15 PM, Steve Hammatt, Mount Vernon WA USA
<[email-masked]> wrote:
> goes up and through the garage attic trusses (above the garageb s drywall
> ceiling)
> toward the houseb s laundry room.  My thought is to interrupt the run to the
> 1.  Planning 2.5 ton 13SEER unit.  What Romex wiring size can I run?  Itb s
> about a
> total of 50b .

30 amp breaker requires 10gauge wire, which will provide a 3% voltage
drop at about 100 feet.

> going through a siding/OSB exterior wall?

I expect they want a standard a/c disconnect, with fuses.  There are
versions that feed through the back, from through the wall.

> 4.  Any nailing recommendations?  Ib m familiar with not nailing (staples)
> too

Minimum spacing is specified by the NEC.  basic rule is no more than
4.5 feet apart, within one foot of any box or fitting, and within 6
inches of a single gang box without a clamp.  Also, wire should be
parallel with the studs (where that makes sense, of course), and needs
to be 1 1/4 away from the edge.  If it can't be, it has to be
protected from nails by a plate, sleeve, or in conduit.  There are
additional complications, but if you follow that, use sense, you'll be
fine.

-- 
David Scheidt
[email-masked]

[email-masked]