Control Panel CPT Grounding
Control Panel CPT Grounding
(OP)
I have a control panel in which the UL508 panel builder grounded the CPT secondary neutral via a screw on the back panel. The back panel is grounded. It seems to me to be a bad practice considering there is a ground bus within the enclosure and the builder just got lazy but I don't know if it is a violation. Is there a requirement that the main bonding jumper of a CPT be grounded to a grounding bus or can the enclosure/back panel serve as part of the bonding jumper? Also, would it be a better practice to not come straight off the X2 terminal but rather apply the bonding jumper at the neutral bus? Thanks!






RE: Control Panel CPT Grounding
16.2 For a transformer or power supply that is required to be grounded in accordance with 16.1, the secondary circuit shall be factory connected by a system bonding jumper to the enclosure and the grounding electrode conductor terminal. The size of the system bonding jumper shall be as specified in 75.1.4, based on the secondary rating. A grounding electrode conductor terminal sized to retain the required grounding electrode conductor in accordance with 75.1.4, based on the secondary rating, shall be provided in the enclosure containing the transformer or power supply and marked as specified in 54.10.
Exception No. 1: When the transformer is rated not more than 1000 volt-amperes and supplies only control circuits, the grounding electrode conductor terminal is able to be omitted and the system bonding jumper shall not be smaller than a 14 AWG (2.1 mm2) copper conductor. The jumper is not otherwise required to be larger than the phase conductors connected to the transformer secondary.
Exception No. 2: Where multiple separately derived systems are provided within the same industrial control panel enclosure, a single grounding electrode conductor terminal suitable for a 3/0 AWG conductor
is able to be supplied in the industrial control panel as the field wiring connection for the common grounding electrode conductor.
Best to you,
Goober Dave
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RE: Control Panel CPT Grounding
Best to you,
Goober Dave
Haven't see the forum policies? Do so now: Forum Policies
RE: Control Panel CPT Grounding
RE: Control Panel CPT Grounding
Best to you,
Goober Dave
Haven't see the forum policies? Do so now: Forum Policies