Service Panel De-Rated ?

**Dan Harris** · 04-29-2014, 05:35 PM

The panel was an original 200 amp Square D panel. 2003 home.
Next to the main 175 amp breaker there was a black plastic plate glued to the cover stating the panel was de-rated Per NEC 690.64 (3) (2)
Why would they de-rate the panel?

**Jerry Peck** · 04-29-2014, 05:39 PM

ARTICLE 690 Solar Photovoltaic Systems
- 690.64 Point of Connection.
- - (2) Bus or Conductor Rating. The sum of the ampere ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed 120 percent of the rating of the busbar or conductor. In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductors.
- - (3) Ground-Fault Protection. The interconnection point shall be on the line side of all ground-fault protection equipment.
- - - Exception: Connection shall be permitted to be made to the load side of ground-fault protection, provided that there is ground-fault protection for equipment from all ground-fault current sources. Ground-fault protection devices used with supplies connected to the load-side terminals shall be identified and listed as suitable for backfeeding.

**Dan Harris** · 04-29-2014, 05:45 PM

Originally Posted by Jerry Peck

ARTICLE 690 Solar Photovoltaic Systems
- 690.64 Point of Connection.
- - (2) Bus or Conductor Rating. The sum of the ampere ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed 120 percent of the rating of the busbar or conductor. In systems with panelboards connected in series, the rating of the first overcurrent device directly connected to the output of a utility-interactive inverter(s) shall be used in the calculations for all busbars and conductors.
- - (3) Ground-Fault Protection. The interconnection point shall be on the line side of all ground-fault protection equipment.
- - - Exception: Connection shall be permitted to be made to the load side of ground-fault protection, provided that there is ground-fault protection for equipment from all ground-fault current sources. Ground-fault protection devices used with supplies connected to the load-side terminals shall be identified and listed as suitable for backfeeding.

No solar or any evidence of prior solar.
Close as I could figure an electric heat pump was added in 2012 to heat the pool