Current Monitoring

Current transformer wiring that originates from a breaker panel is considered a Class 1 circuit by both the National Electrical Code (NEC) and the Canadian Electrical Code (CEC). JBoxes provide a convenient way to isolate CT wiring from Class 2 devices such as CircuitMeter’s WebMeter36F™ product. Corrections to phase error and gain errors are performed by the WebMeter36F™. This enables a flexible installation process utilizing standard Cat5e cables. The JBox-4 is a 4 port configuration allowing a single JBox-4 to connect up to 4 CTs to a WebMeter36F™.

Use any combination of JBox-4’s to connect a total of up to 36 CTs to a WebMeter36F™. Use standard Cat5e cable for to connect the JBox-4 to the WebMeter36F™.


Supported Current Transformers

Solid Core Current Transformers

  • CT040, CT100, CT200

Split Core Current Transformers

  • SP040, SP100, SP200
  • SP400, SP600, SP800
  • Custom Current Transformers up to 6000A

Device Specifications

Isolation Input to Output

  • 2.5 KV (hi-pot test)


  • 50/60 Hz
  • Capture energy information for up to 4 circuits.
  • Simple and convenient way to connect up to 4 CTs to the WebMeter36F™.
  • Ideal for connecting single and multiple phases or remote pieces of equipment to the WebMeter36F™ .
  • Use any combination of JBox-4’s and JBox-8’s to connect a total of up to 36 CTs to a WebMeter36F™.


Safety Standards

  • UL 61010-1
  • CAN/CSA C22.2 No. 61010-1
  • E113521
  • CE

Mechanical & Dimensions

Weight: 640 g (1.4 lbs)
Size: 12.192 cm / 4.80 in (L)
12.192 cm / 4.80 in (W)
5.080 cm / 2.00 in (H)


Operating Temp: 00C to +700C
Storage Temp: -170C to +800C
Humidity Range: 10 to 90%
Enclosure: UL94V-5VA


Supports: 4 CT
Connector Type: Spring Cage
CT Current: 20 mA


RJ45 (T-568B): 1
CT Current: 10 mA
Range: 20A – 6000A