Rules and Guidelines
Want to participate in the discussions? Please read our Community Rules and Guidelines. Need some help? Visit Support and Answers.

  • State Not Answered
  • Locked Locked
  • Replies 13 replies
  • Subscribers 40 subscribers
  • Views 5310 views
  • Users 0 members are here
Options
You may also be interested in
This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

Installation of CT clamp current monitoring devices

Christopher Green

Hi there sparkys!

I work for a company who manufacture CT Clamps to measure current consumption. I'm a presales engineer, not an electrician.

These clamps, as I'm sure you know, simply clip on to a conductor in a consumer unit or elsewhere, and in our case, transmit the information wirelessly to a device which translates and presents the data in a useful fashion.

I'm working on some marketing documentation, and I'd like to be clear about the legality of installing these devices in commercial premises. In order to install these devices, one simply has to clip them around an insulated live conductor, there is no need to turn off the power, or touch any bare metal. I know that British Gas and other companies hand these out to domestic consumers so that they can have a display showing how much energy they're using, so I assume that it is legal for any old idiot to clip these on to an insulated live conductor in a domestic consumer unit.

But what about commercial premises? I don't know the rules - can an unqualified/uncertified person open a RCD box or consumer unit or whatever it's called and clip these CT clamps on to a live conductor in commercial premises? Can an unqualified person even touch a commercial consumer unit?! I would have thought that regs would require a certified electrician to install these things, but one of our selling points is that they don't require professional installation or any permanent modification to the wiring, as they simply clip around an insulated conductor.

I've attached a picture of some of these clamps installed in one of our consumer units. These were actually installed by a certified electrician, but only through coincidence - the guy who did my job before me just happens to be certified, as he worked as an electrician before he started this job!

Any advice on the legal requirements of installing such devices would be appreciated. Obviously it's very important that our marketing materials don't advise anyone to break the law!

I'm asking this question from the UK, but we sell these devices globally, so any advice on different rules in Europe or America or anywhere else would also be welcome.

Thanks everyone!

Parents
  • 0

    Looking at the picture again, I'd wonder about any other consequences about adding these CTs into a CU or DB. The CTs look to be connected using thin (2-core?) cable - is it suitable for a 230V environment (including overvoltages from surges etc. - peaks of a few kV)? - noting how close one of them runs to the bare conductors just above the left hand RCCB. What do the CTs connect to - something SELV/PELV based? Could introducing mains voltages from a fault in the CU be hazardous to people in the proximity of the electronics? What sort of plastic are the CTs housed with - what does it do for the fire rating of the CU? How will it react when the CU is handling faults (e.g. from arcs and sparks emitted by the MCBs, especially when handling larger faults (e.g. 16kA)). Will the CTs do anything for the thermal performance of the CU - e.g. might they interfere with heat dissipation from the MCBs or conductors? or creepage and clearance distances? Generally we have to be very careful about putting any 3rd party equipment in CUs - since they're type tested by the manufacturer using only their own components - I wonder what Hager or whoever would say about this?

       - Andy.

Reply
  • 0

    Looking at the picture again, I'd wonder about any other consequences about adding these CTs into a CU or DB. The CTs look to be connected using thin (2-core?) cable - is it suitable for a 230V environment (including overvoltages from surges etc. - peaks of a few kV)? - noting how close one of them runs to the bare conductors just above the left hand RCCB. What do the CTs connect to - something SELV/PELV based? Could introducing mains voltages from a fault in the CU be hazardous to people in the proximity of the electronics? What sort of plastic are the CTs housed with - what does it do for the fire rating of the CU? How will it react when the CU is handling faults (e.g. from arcs and sparks emitted by the MCBs, especially when handling larger faults (e.g. 16kA)). Will the CTs do anything for the thermal performance of the CU - e.g. might they interfere with heat dissipation from the MCBs or conductors? or creepage and clearance distances? Generally we have to be very careful about putting any 3rd party equipment in CUs - since they're type tested by the manufacturer using only their own components - I wonder what Hager or whoever would say about this?

       - Andy.

Children
  • 0 in reply to AJJewsbury

    Your reply contained so many questions that I've never considered, I have a headache now...

    Thanks for that - you've given me some useful things to research...

Join us to get the best from IET EngX.

Joining EngX lets you personalise your experience so you stay up to date on the topics that interest you, plus you’ll be able to make connections who are looking to collaborate, exchange ideas and more.

Join us Not now

Community Rules & Guidelines