I installed my window air conditioner and the GFCI on the end of the cord
would not reset. I figured I would replace the plug and get an inline
GFCI to replace what was there.

So why the "shielding"?



*Are you sure that was a GFCI on the end and not an AFCI?


http://www.peterspirito.com/afci_faq.htm
What are the National Electrical Code® requirements for AFCI's?

AFCI's were added to the 1999 National Electrical Code® in Section 210-12
for bedroom receptacle outlets beginning on January 1, 2002.

The 2002 NEC® (Section 210.12) requires AFCI's for all bedroom circuit
outlets. An outlet is defined as any point on the wiring system at which
current is taken to supply utilization equipment. This includes
receptacles, lighting fixtures, ceiling fans, smoke alarms, etc.

The 2005 NEC® (Section 210.12) has the same requirements for bedroom
circuit outlets with one exception - the wording changes to specifically
require a Combination Type AFCI beginning January 1, 2008. In all cases
the requirement is to protect the entire branch circuit.

NEC® Article 100 Definitions

.Branch Circuit - The current conductors between the final overcurrent
device protecting the circuit and the outlet(s).
.Outlet - A point on the wiring system at which current is taken to supply
utilization equipment.
Please see the NEC® for the exact wording of the requirements. Some areas
may adopt other effective dates and may expand the requirements beyond the
bedroom circuits. Contact your local authority having jurisdiction (AHJ)
to verify code requirements for your area.

Why do the 1999, 2002, and 2005 versions of the NEC® require AFCI
protection for only bedroom circuits?

NFPA fire statistics show that a high percentage of electrical fires occur
in bedrooms. There are many appliance cords in bedrooms, for example,
radios, clocks, blankets, air conditioners, heaters, TVs, vacuums, as well
as, lamp cords. All of these cords can be trapped/abused leading to arcing
faults. Further, there are long runs of installed wiring (M-B, "Romex")
between the loadcenter and the bedroom outlets. The wiring can be abused
during installation (e.g. stapling) and after installation (driving nails
into the wall etc.) Therefore, the most logical room to start with would
be the bedroom.


*Article 440.65 of the 2008 NEC requires a leakage detector or an AFCI on
corded room air conditioners..