YHDC SCT006 Cable Extension


#1

Hi,

Recently purchased an IotaWatt and a SCT013 to monitor my home incoming mains lead, everything is working great. Expanding upon this, I purchased a number of SCT006s from YHDC to monitor internal home circuits. These CT sensors were delivered with bare cables so I’ll need to extend these and attach a 3.5mm jack for the IoTaWatt.

As per Extending the Current Transformer Cable article a screened twin core microphone cable will be used to extend.

It appears the SCT006 white wire labeled as ‘k’ is connected to the 3.5mm jack “Tip” and the SCT006 red wire labeled as ‘l’ is connected to the 3.5mm jack “Sleeve”. The above article also mentions the requirement to connect the extending microphone cable screen to earth at one end only, however pictures in the blog entry Question regarding precision of CTs (SCT006) show no indication of earthing the cable screen. Could someone please clarify weather earthing is required and if so were?


#2

There is no earth (ground here in the USA) available at either end. It should be OK if you just let it float. Where I’ve added cables to CTs that had none, I simply buy cheap 6ft 3.5mm stereo male-male cords, cut them in half, and use them to get two cords.

One final note. The SCT006 as sold by OEM (I use Echun CTs), in addition to the cord have TVS diode(s) that effectively short the CT when it is not plugged into the IoTaWatt. I cannot overemphasize the importance of either adding diodes, or NEVER unplugging them while they are clamped over an active primary wire. Those CTs are easily damaged.


#3

Thanks very much for the information. SCT006 cables extended, connected (noting the correct attachment sequence) and IoTaWatt is collecting usage information from 7 circuits. :grinning:.