Does anyone know what voltage rating is for the output cable on an SCT-013-000 current transformer?
Here's why I'm asking: In the UK, mains electrical installations are effectively governed by the Wiring Regulations, a comprehensive British Standard. While not the law, it is generally accepted as the best way to comply with laws regarding electricity.
In BS 7671:2008+A1:2011, regulation 518.1 specifies segregation of circuits that are in different voltage bands. The emon would be in Band I, while UK mains are Low Voltage and classified as Band II. When you install a CT inside a domestic consumer unit, the conductors of two voltage bands share an enclosure, and can be considered part of the same wiring system. To overcome the need for segregation, every cable must be insulated for the highest voltage present, which is ~230-250V AC. Does the output cable on the SCT-013-000 have a high enough rating? I can't find this data anywhere.
For info, here is reg 518.1:
Except where one of the following methods is adopted, neither a voltage Band I nor a voltage Band II circuit shall be contained in the same wiring system as a circuit of nominal voltage exceeding that of low voltage, and a Band I circuit shall not be contained in the same wiring system as a Band II circuit:
(i) Every cable or conductor is insulated for the highest voltage present
(ii) Each conductor of a multicore cable is insulated for the highest voltage present in the cable
(iii) The cables are insulated for their system voltage and installed in a separate compartment of a cable ducting or cable trunking system
(iv) The cables are installed on a cable tray system where physical separation is provided by a partition
(v) A separate conduit, trunking or ducting system is employed
(vi) For multicore cable, the cores of the Band I circuit are separated from the cores of the Band II circuit by an earthed metal screen of equivalent current-carrying capacity to that of the largest core of a Band II circuit.
Thanks.
Re: CT output cable voltage rating
As this is a split core clamp it's not really suitable for use inside a CU, much too bulky. I doubt that the shop owners would recommend such usage. Looking at the construction, there are 2 individually insulated conductors within a fairly thick surrounding insulator, so it would seem likely that the insulation is sufficient. You could add a suitable PVC sleeve to ensure that the insulation is adequate.
Re: CT output cable voltage rating
It looks as if the cable is appropriately rated. I have a black-cable c.t. from the shop that has printed along the cable:
"CCC A051009 SHANGHAI SHENTAO TEZHONG XIANLAN YOUXIAN GONGSI RVVB 300/300 V"
I believe the purpose of that regulation is to prevent danger should the insulation become damaged in the process of drawing in the cables in an industrial environment. But the normal way the c.t. is installed is outside of the consumer unit, where the insulation and sheath of the tails provides the necessary insulation.