Re: Cable current capability

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>



 > Original poster: "Jeremy Scott by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <supertux1-at-yahoo-dot-com>
 >
 > Hi,
 >
 > I asked about this a few weeks ago, and I had never
 > done any 240V wiring. I bought and read a lot of NEC
 > Code books about doit-yourself wiring and this is
 > the result:

Jeremy's description, which I've snipped is good..
I'd like to make the following little points, though:

The "code" is a minimum standard.. and following the code doesn't
necessarily guarantee that what you do is going to be safe. The assumption
is that the work is actually being done (or at least checked) by someone
with some experience and general knowledge in the area.  Consider code
compliance "necessary but not sufficient"..

For instance, the code might allow sizing wire for a load in a particular
way. That doesn't mean that it will work optimally, it just means that the
insulation won't melt off the wire and start a fire (that being the goal of
the code: safety)....

 >
 > What you'll want to do is install a circuit and
 > outlet that can power a conventional appliance oven.
 > At least, that's what you'll tell the sales people
 > at your local hardware store or the electrician if
 > you hire one :)
 >
 >
 > If you install the circuit in your garage or
 > outside, you'll probably need a GFCI 50 Amp
 > dual 240V breaker or else you'll probably
 > nullify your home owner's insurance policy.
 > Infact, if you do it any other way than
 > I specified, you will probably be in
 > violation of some code, and you probably
 > won't be covered if your house burns down.
 >
GFCI's aren't necessarily required for a permanently installed single
receptacle of 20A or more intended for a single piece of equipment (i.e. a
refrigerator outlet in the garage).  Certainly, they ARE required for "wet
locations" (bathrooms, etc.) and for general purpose 15A receptacles. (The
20 A/115V receptacles have the "T" shaped opening on one side, instead of
the two parallel flat blades like a normal socket).  There are also some
funny rules about 240V extension cords (aimed primarily at the construction
industry, where they run feeders across the job site to "spiders").

There are also some rules about the minimum height and wiring methods for
receptacles in "hazardous locations" (i.e. your garage).. In short, the
wiring has to be entire enclosed, and the receptacle has to be (I think) 48
inches above the floor.

Don't trust the guy at the store selling the stuff... it's not his house
that will burn down, and he won't have to deal with the code compliance
officer... go to the library and check YOUR local rules.. not all cities use
the NEC, and many have added features, as well.

Depending on the location, you might also need to get a building permit for
electrical modifications.  In general, if you are doing your own work on
your own house, you don't need a licensed contractor, nor have signed and
sealed plans.  The folks at the building department, if asked nicely, may
have a sheet that gives the recommended stuff, or can provide a plan check
and advice.  Sometimes there's a small (<$50) fee for an over-the-counter
plan check (make an appointment!) which might go a long way towards greasing
the skids towards permit issuance.

Whatever you do, permits or not, draw up some rough plans, write down your
calculations (things like why you chose size X wire), what NEC/municipal
code sections you think apply, and save it somewhere.  If it ever does
become an issue (i.e. you're selling the house and need an "after-the-fact
permit" for the work), doing things in a professional way will help a lot...
If you're an electrical contractor doing this every day, you don't need as
much design paperwork, the assumption being that you "know what you're
doing" from experience (and, you're licensed, besides).