Editorial Note on Part 173
Editorial Note: Nomenclature changes to part 173 appear at 70 FR 56098, Sept. 23, 2005.

§ 173.176 Capacitors. ( a ) Capacitors, including capacitors containing an electrolyte that does not meet the definition of any hazard class or division as defined in this part, must conform to the following requirements: ( 1 ) Except for asymmetric capacitors, capacitors not installed in equipment must be transported in an uncharged state.
( 2 ) Each capacitor or module must be protected against a potential short circuit hazard in transport as follows: ( i ) Except for asymmetric capacitors, when a capacitor's energy storage capacity is less than or equal to 10 Wh or when the energy storage capacity of each capacitor in a module is less than or equal to 10 Wh, the capacitor or module must be protected against short circuit or be fitted with a metal strap connecting the terminals; or
( ii ) Except for asymmetric capacitors, when the energy storage capacity of a capacitor or a capacitor in a module is more than 10 Wh, the capacitor or module must be fitted with a metal strap connecting the terminals.
( iii ) When an asymmetric capacitor's energy storage capacity is greater than 0.3 Wh, or when the energy storage capacity of each capacitor in a module is greater than 0.3 Wh, the capacitor or module must be protected against short circuit.
( 3 ) Capacitors containing an electrolyte that meets the definition of one or more hazard class or division as defined in this part, must be designed to withstand a 95 kPa (0.95 bar, 14 psi) pressure differential.
( 4 ) Capacitors must be designed and constructed to safely relieve pressure that may build up in use, through a vent or a weak point in the capacitor casing. Any liquid that is released upon venting must be contained by the packaging or by the equipment in which a capacitor is installed.
( 5 ) Except for asymmetric capacitors, capacitors manufactured after December 31, 2013, or asymmetric capacitors manufactured after December 31, 2015, must be marked with the energy storage capacity in Wh.
( b ) Capacitors must be packed in strong outer packagings. For transport by air, capacitors must be securely cushioned within the outer packagings. Capacitors installed in equipment may be offered for transport unpackaged or on pallets, when the capacitors are afforded equivalent protection by the equipment in which they are contained.
( c ) Capacitors containing an electrolyte not meeting the definition of any hazard class or division as defined in this part, including when configured in a module or when installed in equipment, are not subject to any other requirements of this subchapter.
( d ) Except for asymmetric capacitors, capacitors containing an electrolyte that meets the definition of one or more hazard class or division as defined in this part, with an energy storage capacity of 10 Wh or less are not subject to any other requirements of this subchapter, when they are capable of withstanding a 1.2 m (3.9 feet) drop test unpackaged onto a rigid, non-resilient, flat and horizontal surface without loss of contents.
( e ) Asymmetric capacitors containing an electrolyte that meets the definition of one or more hazard class or division as defined in this part, with an energy storage capacity of 20 Wh or less, including when configured in a module, are not subject to other provisions of this subchapter when the capacitors are capable of withstanding a 1.2 meter (3.9 feet) drop test unpackaged onto a rigid, non-resilient, flat and horizontal surface without loss of contents.
( f ) Except for asymmetric capacitors, capacitors containing an electrolyte meeting the definition of one or more hazard class or division as defined in this part, that are not installed in equipment, and with an energy storage capacity of more than 10 Wh are subject to the requirements of this subchapter.
( g ) Asymmetric capacitors containing an electrolyte meeting the definition of one or more hazard class or division as defined in this part, that are not installed in equipment, and with an energy storage capacity of more than 20 Wh are subject to the requirements of this subchapter.
( h ) Capacitors installed in equipment and containing an electrolyte meeting the definition of one or more hazard class or division as defined in this part, are not subject to any other requirements of this subchapter, provided the equipment is packaged in a strong outer packaging and in such a manner as to prevent accidental functioning of the capacitors during transport. Large, robust equipment containing capacitors may be offered for transport unpackaged or on pallets when the capacitors are afforded equivalent protection by the equipment in which they are contained.
[80 FR 1159, Jan. 8, 2015, as amended at 85 FR 83398, Dec. 21, 2020]