Question: Commercial cooking appliances in households
It seems that commercial cooking appliances installed in households are the new trend in kitchens of high-end houses. Are commercial cooking appliances such as commercial electric ranges listed for use in a household?
Answer
Commercial cooking appliances, such as commercial electric ranges, are not listed for use in a household. UL lists commercial cooking equipment including commercial electric ranges under the category Commercial Cooking Appliances, (KNGT), located on page 231 of the 2004 White Book. The Guide Information states, “This category covers cooking equipment intended for commercial indoor use, such as…ranges, and other appliances for use in commercial kitchens, restaurants, or other business establishments where food is dispensed.” If someone installs a commercial cooking appliance into a home, they are using it in a manner that is not consistent with UL’s certification. These appliances are evaluated for compliance with the Standard for Commercial Electric Cooking Appliances,
UL 197.
UL lists electric ranges intended for use in a home under the category Ranges, Household Electric (KRMX), located on page 238 of the 2004 White Book. These are evaluated for compliance with the Standard for Household Electric Ranges, UL 858. Among some of the differences in listing requirements between commercial ranges and ranges intended for use in a household is surface temperatures, and because children may be in the vicinity of the range, especially those surface temperatures below 3 feet above the floor. UL 197, the Standard for Commercial Electric Cooking Appliances allows a “Caution — Hot Surface” marking in lieu of limiting surface temperatures as is required in UL 858. UL 858 also requires that the surface heating units need two separate motions to turn them on (push and turn). UL 197 does not. These are a few of the differences between equipment intended to be used in a commercial kitchen and equipment intended to be used in a household kitchen.
Question: AFCI indicator
If an AFCI indicator plugged into a receptacle protected by an AFCI doesn’t trip the AFCI, does that mean the AFCI protecting the circuit is defective and should be replaced?
Answer
No, an AFCI that does not trip when used with an AFCI indicator does not necessarily mean that the AFCI is defective and needs to be replaced. AFCI indicators on the market today are not AFCI testers, they are listed by UL as AFCI indicators under one of two product categories including Outlet Circuit Testers (QCYU) located on page 91 of the 2004 White Book or Measuring, Testing and Signal Generation Equipment (PICQ), which can be located on UL’s Online Certification Directory athttp://www.ul.comand enter PICQ at the category code search.
These AFCI indicators provide an indication if a selected receptacle is protected by an AFCI. î”ese indicators are generally used to reduce the number of trips to the panelboard location to push the test button on the AFCI circuit breaker. AFCI indicators produce a waveform that mimics an arc and because each AFCI manufacturer has a unique way of detecting an arc, every AFCI indicator may not trip every AFCI. When in doubt, push the test button on the AFCI circuit breaker to be sure.
Please note the only accepted method for testing an AFCI is to push the “test” button provided as an integral part of the AFCI itself.
AFCI indicators are provided with instructions that state the proper way to “test” an AFCI breaker. AFCI indicators are required to be marked on the product or provided in the user instructions as follows “CAUTION: AFCIs recognize characteristics unique to arcing, and AFCI indicators produce characteristics that mimic some forms of arcing. Because of this the indicator may give a false indication that the AFCI is not functioning properly. If this occurs, recheck the operation of the AFCI using the test and reset buttons. The AFCI button test function will demonstrate proper operation.”
Question: Type NM-B cable
Type NM-B cable conductors are rated 90°C, yet they are not marked, are they required to comply with the same requirements as THHN? Why aren’t they marked THHN?
Answer
Type NM cable is listed under the category NonMetallic Sheathed Cable (PWVX), located on page 84 of the 2004 UL General Information for Electrical Equipment Directory (the White Book). The Guide Information states that “This cable contains conductors rated 90°C; however, the ampacities of the cable are those of 60°C conductors as specified in Article 334 and Table 310.16 of the NEC.”
Yes, the conductors must comply with Type THHN requirements in every way except that they are not permitted to be printed with that designation. This is done in an attempt to prevent a user from seeing THHN printed on the conductor and then using the THHN ampacity from Article 310. As you know, NM conductors must use 60°C ampacities per NEC 334.80.
