Installing CT clamps in commercial premises

fishkake said:

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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Electro-tech said:

Do your CT clamps conform to any international or British Standards & codes to start with.
You would hope that a 'Skilled Person 'which now replaces 'Competent person' as per BS 7671 a person has undertaken adequate training & practical skills, & who is able to perceive risks & avoid hazards which electricity can create. Electricity at Works Act 1989 Still say a competent person. I think Knowledge of Safe Isolation of any Electrical Installation as a bare minimum.

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fishkake said:

The spec sheet says that the clamp:

satisfies the requirements of Annex II of the R&TTE Directive and has been independently tested and found compliant with the essential requirements of:
• BS EN 61326:2006 Electromagnetic Compatibility
• BS EN 60950-1:2006+A2:2013 Information technology equipment. Safety. General requirements

Is that what you mean?

General common sense is always applied, and we always include a polite version of "don't do this unless you really know what you're doing" in our advice and documentation. But for the marketing material, I'm concerned about making sure what we say is legal.

At present, 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 (legally) acceptable?

We don't specifically advise regarding opening a fuse board or precisely what a "skilled person" or a "competent person" can or can't do, we're not qualified to advise on those matters. But it's a selling point that our customers don't have to contract an electrician, or make permanent alterations to wiring in order to fit these sensors.

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There is also BS EN / IEC 61869-2 2013 Edition, January 31, 2013, which covers instrument transformers. Most electrical items we fit have instructions to be carried out by a qualified or Skilled person & most of the time you are fitting to the manufacturer's specification. ​

James said:

could be an easy job if the board looks like this,
View attachment 99432

more of a problem if it looks like this

View attachment 99433

Absolute nightmare if this is what you are dealing with

View attachment 99434

start looking at something like this and behind many covers you will find large bits of copper that will kill you.

View attachment 99435View attachment 99436

As you can see, there is no one size fits all approach to opening up industrial / commercial electrical panels

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DPG said:

There's also the issue that someone moving cables about and trying to cram several CTs in the board could well end up loosening connections. All connections should really be checked after the work has been done.

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fishkake said:

This is quite true, but I'm not talking about what "should" be done, I'm merely talking about legality. What "should" be done is covered in installation documentation and advice. We don't fit the equipment, we only manufacture and sell it, and it's up to the installer to do what's right. I'm not trying to shirk responsibility, but this is marketing information, so it's about selling points. Anyone who uses marketing information as advice on good practice frankly deserves what they get! I'm just asking how I can put this in the document, can I say "fitting these sensors doesn't require the services of a certified electrician, it can be carried out by any competent person" ?

It's a bit like BMW advertising that the M3 goes from 0 to 62mph in 4 6 seconds - they don't have to say "but you really shouldn't ever do that," they're just stating the fact.

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