53569

神经网络昆斯林的新闻组分类2006

Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!bogus.sura.net!howland.reston.ans.net!spool.mu.edu!nigel.msen.com!sdd.hp.com!crash!cmkrnl!jeh
From: [e-mail]
Newsgroups: sci.electronics
Subject: Electrical wiring FAQ (was: A question about 120VAC outlet wiring..
Message-ID: <[e-mail]>
Date: 15 Apr 93 21:33:30 PDT
References: <[e-mail]>
Reply-To: [e-mail]
Followup-To: poster
Keywords: 120 240 AC outlets wiring power shock gfci
Expires: 15 May 93 21:35:16 PDT
Distribution: world
Organization: Kernel Mode Systems, San Diego, CA
Lines: 1547

Since electrical wiring questions do turn up from time to time on
sci.electronics (and the answers aren't always apparent, even to those skilled
in electronics), I am hijacking the following FAQ and posting a copy here. 
I've asked the writers to cross-post to sci.electronics in the future. 

	--- [e-mail]


X-NEWS: cmkrnl news.answers: 6685
Newsgroups: misc.consumers.house,rec.woodworking,news.answers,misc.answers,rec.answers
Subject: Electrical Wiring FAQ
Message-ID: <wirefaq_733900891@ecicrl>
From: [e-mail] (Chris Lewis)
Date: 4 Apr 93 05:21:49 GMT
Reply-To: [e-mail] (Wiring FAQ commentary reception)
Followup-To: poster
Expires: 2 May 93 05:21:31 GMT
Organization: Elegant Communications Inc., Ottawa, Canada
Summary: A series of questions and answers about house wiring
Approved: [e-mail]
Supersedes: <wirefaq_732691289@ecicrl>
Lines: 1524

Archive-name: electrical-wiring
Last-modified: Sun Feb 21 16:56:10 EST 1993

	    Frequently Asked Questions on Electrical Wiring

		Steven Bellovin ([e-mail])
		Chris Lewis ([e-mail])

	    Comments to (automatic if you reply to this article):
		    [e-mail]

This FAQ is formatted as a digest.  Most news readers can
skip from one question to the next by pressing ^G.

Answers to many other topics related to houses can be obtained from
the misc.consumers.house archive; send an empty piece of mail to
[e-mail] for information.

Changes to previous issue marked with "|" in left column.  Watch
particularly for "NEW" in the Questions list for new or substantively
changed answers.

Note that this is now a registered FAQ - cross-posted to news.answers
and should appear in the FAQ list of lists.

Subject: Questions answered in this FAQ

	Introduction/Disclaimers
	What is the NEC?  Where can I get a copy?
	What is the CEC?  Where can I get a copy?
	Can I do my own wiring?  Extra pointers?
	What do I need in the way of tools?
	What is UL listing?
	What is CSA approval?
	Are there any cheaper, easier to read books on wiring?
	Inspections how and what?  Why should I get my wiring inspected?
	My house doesn't meet some of these rules and regulations.
	A word on voltages: 110/115/117/120/125/220/240
	What does an electrical service look like?
	What is a circuit?
	"grounding" versus "grounded" versus "neutral".
	What does a fuse or breaker do?  What are the differences?
	Breakers?  Can't I use fuses?
	What size wire should I use?
	Where do these numbers come from?
	What does "14-2" mean?
	What is a "wirenut"/"marrette"/"marr connector".  How are they used?
	What is a GFI/GFCI?
	Where should GFCIs be used?
	Where shouldn't I use a GFCI?
	What is the difference between a GFCI outlet and a GFCI breaker?
	What's the purpose of the ground prong on an outlet, then?
	Why is one prong wider than the other?  Polarization
	What kind of outlets do I need in a kitchen?
	Where must outlets and switches be in bathrooms?
	What is Romex/NM/NMD?  What is BX?  When should I use each?
	Should I use plastic or metal boxes?
	Junction box positioning?
	Can I install a replacement fixture?
	What does it mean when the lights brighten when a motor starts?
	What is 3 phase power?  Should I use it?  Can I get it in my house?
	Is it better to run motors at 110 or 220?
	What is this nonsense about 3HP on 110V 15A circuits?
	How do I convert two prong receptacles to three prong?
	Are you sure about GFCIs and ungrounded outlets?
	    Should the test button work?
	How should I wire my shop?
	Underground wiring
	Aluminum wiring
	I'm buying a house!  What should I do?
	What is this weird stuff?  Old style wiring
	Where do I buy stuff?


Subject: Introduction/Disclaimers

	Although we've done a fair bit of wiring, we are not
	electricians, and we cannot be responsible for what you do.  If
	you're at all uncertain about what is correct or safe, *don't
	do it*.  Contact someone qualified -- a licensed electrician,
	or your local electrical inspector.  Electricity is no joke;
	mistakes can result in shocks, fires, or electrocution.

	Furthermore, our discussion is based on the U.S. National
	Electrical Code (NEC) and the Canadian Electrical code (CEC).
	To the best of our abilities, we have confirmed every detail
	with the electrical code, but we don't quote sections
	simply to keep this thing readable.  If you think we're wrong,
	we invite you to correct us, but please - quote references!

	The NEC and the CEC do not, in and of themselves, have the
	force of law.  Many municipalities adopt it en toto.  Others,
	however, do not.  Check your with your local building
	department (and <provincial> Hydro Inspection Offices in
	Canada) to find out what applies in your area.  Also,
	your local electrical utility may also have special requirements
	for electrical service installation.  Bear in mind, too, that
	we say here applies primarily to ordinary single-family
	residences.  Multi-family dwellings, mobile homes, commercial
	establishments, etc., are sometimes governed by different
	rules.

	Also note that, contrary to popular belief in the U.S. (and in
	some parts of Canada), Canada is not a wholly-owned subsidiary
	of the U.S.  Consequently, the NEC does not apply in Canada.
	Lots of things are the same, including voltages, line
	frequencies, and the laws of physics.  But there are a number
	of crucial differences in the regulations.  Where we can, we've
	noted them, flagging the relevant passages with ``NEC'' or
	``CEC''.

	Remember that the CEC and NEC are minimal standards.  It is often
	smart to go beyond their minimal requirements.

Subject: What is the NEC?  Where can I get a copy?

	The NEC is a model electrical code devised and published by the
	National Fire Protection Association, an insurance industry group.
	It's revised every three years.  The 1993 version has been released.
	You can buy a copy at a decent bookstore, or by calling them directly
	at 800-344-3555.  The code exists in several versions.  There's the
	full text, which is fairly incomprehensible.  There's an abridged
	edition, which has only the sections likely to apply to most houses.
	And there's the NEC Handbook, which contains the ``authorized
	commentary'' on the code, as well as the full text.  That's the
	recommended version.  Unfortunately, there's no handbook for
	the abridged edition.  And the full handbook is expensive --
	US$65 plus shipping and handling.

Subject: What is the CEC?  Where can I get a copy?

	The Canadian Standards Association is an organization made up
	of various government agencies, power utilities, insurance
	companies, electrical manufacturers and other organizations.
	The CSA publishes CSA Standard C22.1 which is updated every two
	or three years.  Each province adopts, with some amendments,
	this standard and publishes a province-specific code book.
	Since each province publishes its own slightly modified
	standard, it would be somewhat confusing to obtain the CSA
	standard itself.  In this FAQ, "CEC" really means the
	appropriate provincial standard.  In particular, this FAQ is
	derived from the Ontario Hydro Electrical Safety Code, 20th
	edition (1990).  Which is in turn based on CSA C22.1-1990 (16th
	edition).  While differences exist between the provinces, an
	attempt has been made to avoid specific-to-Ontario detail.

	The appropriate provincial code can be obtained from electrical
	inspection offices of your provincial power authority.  In
	Ontario, it's Ontario Hydro.  The Ontario Hydro book isn't
	overly fat.  It's about C$25, and includes mailed updates.  I
	hear that these standards are somewhat easier to read than the
	equivalent NEC publications.

	Don't bother asking in Quebec - DIY wiring is banned throughout
	the province.

Subject: Can I do my own wiring?  Extra pointers?

	In most places, homeowners are allowed to do their own wiring.
	In some, they're not.  Check with your local electrical
	inspector.  Most places won't permit you to do wiring on other's
	homes for money without a license.  Nor are you permitted to do
	wiring in "commercial" buildings.  Multiple dwellings (eg: duplexes)
	are usually considered "semi-commercial" or "commercial".  However,
	many jurisdictions will permit you to work on semi-commercial
	wiring if you're supervised by a licensed electrician - if you can
	find one willing to supervise.

	If you do your own wiring, an important point:

	Do it NEAT and WELL!  What you really want to aim for is a better
	job than an electrician will do.  After all, it's your own home,
	and it's you or your family that might get killed if you make
	a mistake.  An electrician has time pressures, has the skills
	and knows the tricks of the trade to do a fast, safe job.
	In this FAQ we've consciously given a few recommendations that
	are in excess of code, because we feel that it's reasonable,
	and will impress the inspector.

	The inspector will know that you're an amateur.  You have to
	earn his trust.  The best way of doing this is to spend your
	time doing as neat a job as possible.  Don't cut corners.
	Exceed specifications.  Otherwise, the inspector may get extremely
	picky and fault you on the slightest transgressions.

	Don't try to hide anything from the inspector.

	Use the proper tools.  Ie: don't use a bread knife to strip
	wires, or twist wires with your fingers.  The inspector
	won't like it, and the results won't be that safe.  And it
	takes longer.  And you're more likely to stick a hunk of
	12ga wire through your hand that way.

	Don't handle house wire when it's very cold (eg: below -10C
	or 16F).  Thermoplastic house wire, particularly older types
	become very brittle.

Subject: What do I need in the way of tools?

	First, there's the obvious -- a hammer, a drill, a few
	screwdrivers, both straight and Phillips-head.  If you're 
	lucky enough to live in Canada (or find a source of CSA-approved
	devices) you need Robertson ("square recess") screwdrivers
	(#1 and #2) instead of phillips.

	For drilling a few holes, a 3/4" or 1" spade bit and 1/4" or
	3/8" electric drill will do.  If you're doing a lot, or
	are working with elderly lumber, we recommend a 1/2" drill
	(right-angle drills are wonderful.  Can be rented) and
	3/4" or 1" screw-point auger drill bits.  These bits pull
	you through, so they're much faster and less fatiguing, even
	in 90 year old hardwood timbers.

	Screw-driver bits are useful for drills, expecially if you
	install your electrical boxes using screws (drywall screws
	work well).
	
	For stripping wire, use a real wire stripper, not a knife or
	ordinary wire cutters.  Don't buy the $3 K-mart "combo stripper,
	crimper and bottle opener" types.  You should expect to pay
	$15 to $20 for a good "plier-type" pair.  It will have sized
	stripping holes, and won't nick or grab the wire - it should
	be easy to strip wire with it.  One model has a small hole in the
	blade for forming exact wire loops for screw terminals.  There
	are fancier types (autostrip/cut), but they generally aren't
	necessary, and pros usually don't use them.

	A pair of diagonal side cutter pliers are useful for clipping ends
	in constricted places.  Don't use these for stripping wire.

	You will need linesman pliers for twisting wires for wire nuts.

	You should have a pair of needle-nose pliers for fiddling
	inside boxes and closing loops, but it's better to form wire
	loops with a "loop former hole" on your wire stripper - more
	accurate.

	If you're using non-metallic cable, get a cable stripper for
	removing the sheath.  Or, do what some pros do, they nick the
	end of the sheath, grab the ground wire with a pair of pliers,
	and simply rip the sheath back using the ground wire as a
	"zipper", and cut the sheath off.  You shouldn't try to strip
	the sheath with a knife point, because it's too easy to
	slash the insulation on the conductors.  Apparently Stanley