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Re: [Shop-talk] Electrical install questions

To: "Steve Hammatt, Mount Vernon WA USA" <gsteve@hammatt.com>
Subject: Re: [Shop-talk] Electrical install questions
From: David Scheidt <dmscheidt@gmail.com>
Date: Fri, 31 Jul 2015 22:36:04 -0500
Cc: shop-talk <Shop-talk@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: shop-talk@autox.team.net
References: <1804233A391A40F694D4960525807B75@StevePC>
On Fri, Jul 31, 2015 at 6:15 PM, Steve Hammatt, Mount Vernon WA USA
<gsteve@hammatt.com> wrote:
> 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 garageb s drywall
> ceiling)
> toward the houseb s 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?  Itb s
> about a
> total of 50b .

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


> 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?

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
> tight on the Romex.  Spacing suggestions?

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
dmscheidt@gmail.com
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