CT Wire Length and Extension

Depending on the type of CT used, the leads may be extended varying distances.

For 5A CTs, refer to this table: http://www.elkor.net/pdfs/5A_CT_Distance.pdf

For mA CTs (MSCTx Series, MS Series, MCTx Series):
16AWG ~ 800ft
18AWG ~ 400ft
20AWG ~ 300ft
22AWG ~ 200ft

Longer distances are possible but should be avoided.


For 333mV CTs, the CT leads should be kept as short as possible. This is because these types of CTs act as a voltage source and are susceptible to electrical interference. The resistance of the wire also acts as a voltage divider and is subject to cause errors in the readings.

In all cases, the proper insulation rating must be observed for the CT, depending on the voltage level of the system. All local and national electrical codes must be observed.