For more details call:


A frequent cause of electrical/electronic equipment failure is AC power line surges. This is especially true in the case of sensitive electronic equipment such as CATV systems, traffic controllers, data processing equipment, telecommunications systems, etc. These power line surges can vary from noise-like transients to spectacular lightning induced surges. Therefore, the effect on costly equipment can vary from a slow degradation of performance to catastrophic failure.

The HE121 is an excellent choice to protect your sensitive electronic equipment. The unit is a 3-stage hybrid, solid state MOV surge protector. The unit offers common and normal mode protection along with a complex AC line filter system. The HE121 also includes a replaceable fuse that will disconnect the line if the internal protection fails. An LED indicator is also utliized to identify when the unit is operating normally or requires service.

Be sure to disconnect AC source prior to replacing the fuse.

Download Specifications Sheet (PDF}


Operating Voltage 120 VAC
Maximum Operating Current 15 Amps
Operating Frequency 47-63 Hz
Peak Surge Current (8 x 20us) 39KA
Clamp Voltage 325 VAC
EMI Attenuation >40dB (110KHz to 100 Mhz)
Modes of Protection L-L, L-N, and N-G
Status Indication Power On and MOV Failure
Connection Type 3 Position Terminal Block
Operating Temperature -40° to +85° C
Dimensions 1.8”H x 2.9”W x 5.3”L
Weight 10 oz
Warranty 5 Years


  • Total Solid State Design
  • Low Clamp Voltage
  • 5 Nanosecond Response Time
  • 3KA Capability (8x20us)
  • Automatic Recovery
  • 120 VAC Protection
  • Replaceable Fuse
  • Failure Indicator
  • 5 Year Warranty