DIYbanter - View Single Post - Are Circuit Breakers Over-rated?

Pete C.

wrote:

On Mon, 02 Nov 2009 17:54:12 -0500, "Pete C."
wrote:

wrote:

On Mon, 02 Nov 2009 15:46:55 -0500, "Pete C."
wrote:

wrote:

On Mon, 2 Nov 2009 07:12:55 -0800 (PST), Jeffy3
wrote:

Our 55 year-old house still runs on fuses . We have never upgraded to
a circuit breaker . We hardly ever blow fuses (it's been years
actually). We even run our heater and air conditioner off an
individual fuse box installed 25 years ago. We have an electrician
coming out to give us an estimate to upgrade to a circuit breaker, but
since we've made the appointment we've heard from two people who say
fuses are better and why bother spending the money if we don't have
any problems. Thoughts ?

If the fuses are properly sized they are safer than breakers because
they fail "open". A breaker can fail closed and provide no protection
(Google Federal Pacific and read the stories)
If you have the proper sized type S adapters and Type S fuses they
fully comply with the 2008 code. You could install one tomorrow in new
construction ... if someone made the panel.
Unfortunately a home inspector would flag fuses as a defect, but most
HIs are generally clueless when it comes to code and they state that
in their contract disclaimer.

Where do you find the necessary AFCI fuses for the bedroom circuits?

In that mythical "device" type AFCI that 210.12(B) ex1 alludes to.

... and that is virtually all receptacles now.

AFCI, not GFCI.

210.12(b) clearly states an AFCI circuit breaker listed to provide
protection to the *entire branch circuit*. A receptacle could never fill
that requirement.

Read it again, particularly exception 1
Where does it say "breaker"?
Ex 1 says essentially
You can come off your fuse panel in a metal raceway to a box with a
device type AFCI (similar to the device GFCI) then on to your
protected circuits.

That would be new since my NEC2002 book, including the expansion to
rooms other than bedrooms. The NEC2002 had no such exception and
specifically indicated protection for the "entire branch circuit". Since
I live in an area with no code, permits or inspections, NEC2002 is quite
sufficient for my needs.

from the book;
210.12 Arc-Fault Circuit-Interrupter Protection.
(A) Definition: Arc-Fault Circuit Interrupter (AFCI). A device
intended to provide protection from the effects of arc faults by
recognizing characteristics unique to arcing and by functioning to
de-energize the circuit when an arc fault is detected.
(B) Dwelling Units. All 120-volt, single phase, 15- and 20-ampere
branch circuits supplying outlets installed in dwelling unit family
rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms,
sunrooms, recreation rooms, closets, hallways, or similar rooms or
areas shall be protected by a listed arc-fault circuit interrupter,
combination-type, installed to provide protection of the branch
circuit.
FPN No. 1: For information on types of arc-fault circuit interrupters,
see UL 1699-1999, Standard for Arc-Fault Circuit Interrupters.
FPN No. 2: See 11.6.3(5) of NFPA 72®-2007, National Fire Alarm Code®,
for information related to secondary power supply requirements for
smoke alarms installed in dwelling units.
FPN No. 3: See 760.41(B) and 760.121(B) for power-supply requirements
for fire alarm systems.
Exception No. 1: Where RMC, IMC, EMT or steel armored cable, Type AC,
meeting the requirements of 250.118 using metal outlet and junction
boxes is installed for the portion of the branch circuit between the
branch-circuit overcurrent device and the first outlet, it shall be
permitted to install a combination AFCI at the first outlet to provide
protection for the remaining portion of the branch circuit.