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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!

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  • 0

    This discussion is going to open a can of worms!

    Firstly, such a device can only measure current. To measure power, which is the thing that most people are interested in, one needs to know the voltage & the power factor (angle between voltage).

    The CTs provided by BG and others are intended to be clamped onto meter tails. Such an action does not require the removal of any kind of cover or lid or any isolation. As such, it can be performed by an "ordinary person".

    Removing the lid of a consumer unit/distribution board, whether in a domestic or commercial premises is an entirely different matter. I would consider it ill advised to suggest to an "ordinary person" that he removes such a cover and attempts to fit CTs to the wiring within. Without proper isolation & proving dead (which an 'ordinary person' is unlikely to be trained to do) it would be easy to come into contact with live terminals even though the main switch is OFF and nothing in the property appears to be powered.

    I would strongly suggest that fitting CTs inside a consumer unit or a commercial distribution board IS a task for a competent trades person.

Reply
  • 0

    This discussion is going to open a can of worms!

    Firstly, such a device can only measure current. To measure power, which is the thing that most people are interested in, one needs to know the voltage & the power factor (angle between voltage).

    The CTs provided by BG and others are intended to be clamped onto meter tails. Such an action does not require the removal of any kind of cover or lid or any isolation. As such, it can be performed by an "ordinary person".

    Removing the lid of a consumer unit/distribution board, whether in a domestic or commercial premises is an entirely different matter. I would consider it ill advised to suggest to an "ordinary person" that he removes such a cover and attempts to fit CTs to the wiring within. Without proper isolation & proving dead (which an 'ordinary person' is unlikely to be trained to do) it would be easy to come into contact with live terminals even though the main switch is OFF and nothing in the property appears to be powered.

    I would strongly suggest that fitting CTs inside a consumer unit or a commercial distribution board IS a task for a competent trades person.

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  • 0 in reply to AdrianWint

    Sorry - as I said, I'm not an electrician, so I tend to use the words "power," "energy," "electricity" and "current" interchangeably, which I'm sure is very annoying to people like you! I'm in IT, so I get equally annoyed when people say "memory" when they mean storage, or when people say "CPU" when they mean PC!! I do actually know the difference between current and power, but to a layman they often mean the same thing!

    A lot of what you're talking about here is about being sensible. We can handle that appropriately; all of our documentation and advice contains a polite version of "don't do this unless you really know what you're doing" - my question was just about the legality of it, for documentation purposes. Personally, I find it amazing how much vague terms like "competent" are used within electric and gas - in my opinion, nobody should even go near a consumer unit without being certified to do so, but my opinion and the law are wildly different things!

    The reason I want to be clear about this is because it is one of our selling points that a customer doesn't have to pay a qualified electrician to install them - seriously, some of you guys are downright extortionate!! :)

    Based on your and others' comments, I've included the line "The sensors are non-intrusive; they do not require any permanent modifications to the circuit and can be installed by any electrically competent person." Does that sound acceptable?

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