[size=3]Look this over and identify the items related to an inspection, I also would look at the UL Marking Guide for Panelboards available from www.ul.com
[size=3]This category covers lighting and power panelboards rated 600 V or less.
Panelboards are intended for mounting in cabinets or cutout boxes
which may be provided with the panel or provided separately. Only panelboards
which are marked to indicate that they are for use in a specific
box and panelboards labeled as ‘‘Enclosed Panelboards’’ have been investigated
to determine that box wiring space is adequate.
**USE, INSTALLATION AND MARKINGS
Enclosed panelboards identified with an enclosure type designation are
intended for use as indicated in Electrical Equipment for Use in Ordinary
Some enclosed panelboards have one or more openings for plug-in watt
hour or similar meters. Such panelboards which are marked for outdoor
use have, except for the joint between the plug-in meter and opening,
been investigated for rain tightness.
Some panelboards are suitable for use as service equipment and may be
so marked. Such marking is part of the Listing Mark as noted below or is
an integral part of other required markings. Panelboards which are
marked to indicate that they are suitable for use as service equipment and
which can be removed from the enclosure are marked to identify the specific
box or boxes in which they are intended to be installed. If the acceptability
of such a panelboard for use as service equipment depends upon
the condition of installation or use, the panelboard is marked to indicate
Some panelboards incorporate neutrals factory bonded to the frame or
enclosure. Such units are marked ‘‘Suitable Only For Use As Service
Panelboards marked for use at services may also be used to provide the
main control and means of cutoff for a separately derived system.
Panelboards are marked with their short-circuit current rating in RMS
symmetrical amps. The marking states that short-circuit ratings are limited
to the lowest interrupting rating of (1) any device installed or intended to
be installed therein and/or (2) any combination series-connected device.
However, for combination series-connected devices, the short-circuit current
rating marked on the panelboard may be higher than the short-circuit
current rating of a specific circuit breaker installed or to be installed in the
panelboard. This higher rating is valid only if the specific overcurrent
devices identified in the marking are used within or ahead of the panelboard
in accordance with the marked instructions.
Panelboards to which units (circuit breakers, switches, etc.) may be
added in the field are marked with the name or trademark of the manufacturer
and the catalog number or equivalent of those units that are
intended to be installed in the field. Individual Circuit Breakers and
Ground Fault Circuit Interrupters (DKUY) may also be classified and
marked as being suitable for use in certain panelboards in place of specific
units marked on the panelboard.
Where in normal operation the load will continue for 3 hours or more,
molded-case circuit breakers and fused switches other than fused power
circuit devices should not be loaded to exceed 80 percent of their current
rating, unless the device is otherwise marked. Low Voltage AC Power
Switching Devices (PAPU) and Fused Power Circuit Devices (IYSR) used
in panelboards are suitable for continuous use at 100 percent of their rating.
Some panelboards may be provided with ground-fault protection for
services or major feeders. The circuit(s) so protected will be identified by a
marking such as on a wiring diagram.
Panelboards as Listed herein are for use with copper conductors unless
marked to indicate which terminals are suitable for use with aluminum
conductors. Such marking shall be independent of any marking on terminal
connectors and shall be on a wiring diagram or other readily visible
location. If all terminals are suitable for use with aluminum conductors as
well as with copper conductors the panelboard will be marked ‘‘Use Copper
or Aluminum Wire.’’ A panelboard employing terminals or main or
branch circuits units, individually marked ‘‘CU-Al’’ will be marked as
noted above or ‘‘Use Copper Wire Only.’’ The latter statement indicates
that wiring space or other factors make the panelboard unsuitable for aluminum
Unless the panelboard is marked to indicate otherwise, the termination
provisions are based on the use of 60°C ampacities for wire sizes 14–1
AWG, and 75°C ampacities for wire sizes 1/0 AWG and larger. However,
3-wire, single phase service entrance or feeder conductors for dwelling
units may be as covered in Note 3 to Table 310-16 of ANSI/NFPA 70,
‘‘National Electrical Code’’ (NEC).
Some panelboards, constructed with interlocked main switching and
overcurrent protective devices, have been investigated for use in optional
standby systems in accordance with Article 702 of the NEC and are
marked ‘‘Suitable for use in accordance with Article 702 of the National
Electrical Code ANSI/NFPA 70,’’ or, if provided within kit form, ‘‘Suitable
for use in accordance with Article 702 of the National Electrical Code
ANSI/NFPA 70 when provided with interlock kit Cat No. ____.’’
**CLASS CTL PANELBOARDS
Class CTL panelboards are identified by the words ‘‘Class CTL’’ on the
Underwriters Laboratories Inc. Follow-Up Service Listing Mark.
Class CTL panelboards incorporate physical features which, in conjunction
with the physical size, configuration, or other means provided in
Class CTL circuit breakers, fuse holders, or fusible switches, are designed
to prevent the installation of more overcurrent protective poles than that
number for which the device is designed and rated.
RECREATIONAL VEHICLE (RV) PANELBOARDS
Some Listed enclosed panelboards in this category have been investigated
for RV use only. These panelboards generally consist of a line
voltage/branch circuit section that complies with the requirements of UL
67, ‘‘Panelboards.’’ The low voltage compartment complies with UL 458,
‘‘Power Converters/Inverters and Power Converter/Inverter Systems for
Land Vehicles and Marine Crafts’’ and is intended to be installed in accordance
with Article 551 of the NEC. Such enclosed panelboards are identi-
fied by a Listing Mark for RVs. RV panelboards do not have inverter functions.
Devices having combination panelboard/inverter capability are
covered under Power Converters/Inverters and Power Converter/Inverter
For additional information, see Electrical Equipment for Use in Ordinary
The basic standard used to investigate products in this category is UL
The Listing Mark of Underwriters Laboratories Inc. on the product is the
only method provided by UL to identify products manufactured under its
Listing and Follow-Up Service. The Listing Mark for these products
includes the UL symbol (as illustrated in the Introduction of this Directory)
together with the word
²LISTED,² a control number, and one of the
following product names as appropriate: ‘‘Panelboard,’’ ‘‘Enclosed Panelboard,’’
‘‘Marine, Enclosed Panelboard for Use on Vessels Over 65 Feet,’’
‘‘Enclosed RV Panelboard.’’ The product name may include the wording
‘‘Class CTL’’ or ‘‘Suitable For Use As Service Equipment’’ where appropriate.
The product name ‘‘Enclosed Panelboard’’ covers both the panel and
enclosure provided with it.
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