How do I read the markings printed on the outside of electric wires?
TAIFULONG E204798 FU AWM 3321 VW-1 IBAWG 150°C 600V FENG TAI ELECTRONIC.


First, TAIFULONG is the cable brand.

E204798 I do not know.

The FU is actually “ЯU”, the symbol for the Underwriters Laboratories Recognized Component Mark:


  These are Marks consumers rarely see because they are specifically
  used on component parts that are part of a larger product or system.
  These components may have restrictions on their performance or may be
  incomplete in construction. The component recognition marking is found
  on a wide range of products, including some switches, power supplies,
  printed wiring boards, some kinds of industrial control equipment and
  thousands of other products.


AWM indicated Underwriters Lab Appliance Wiring Material:


  UL offers a broad and comprehensive certification program for
  appliance wiring material (AWM). This program enables manufacturers to
  demonstrate compliance in an objective and credible fashion, while
  enabling thousands of OEMs to source safer, compliant products.


3321 indicates a specific AWM rating.


  Appliance Wiring Material Style Number Designations: 3000–3999: Single
  conductor, thermosetting-insulated wire.


Thermoset wire insulation BURNS, compared to thermoplastic insulation, which melts and reforms. The specifics of the rating I do not have.

VW-1 indicates extra flame testing rating:


  Where a greater degree of flame retardancy is desired, over that
  required for all wire &amp; cable, this Vertical Wire flame test can be
  imposed. This is an optional flame rating, and products meeting the
  test may carry the additional marking "VW-1."


The IBAWG is actually 18 AWG. This means 18 Gauge Wire, according to the American Wire Gauge standard (aka the Brown &amp; Sharpe wire gauge). This is the wire Size. Typical house mains internal wiring is 12~14 AWG, depending on current needs. 16 and 18 AWG is often for appliance cord wire and low voltage wire systems.

150°C is the Insulation breakdown temperature. It will melt/burn at 150 degrees Celsius. Normal temperatures will not exceed this for household in-wall wiring.

600V is the Insulation breakdown voltage. Any voltage meeting or exceeding this will result in no insulation. That's bad.

Feng Tai Electronic is the Manufacturer.