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.

The law in the UK does not prevent anyone from opening a fuseboard, or anything else (well after the meter anyway) though some insurance policies may be invalidated in commercial situations.

There is no single certificate that makes someone an electrician. In the same way the wiring regs are not a legal requirement in most situations either, so what is 'competent' enough  is cloudy.

Now the level of understanding needed to fit one of these is pretty minimal but many large commercial  boards, especially older ones, have large blocks of live metal exposed, perhaps even when the final circuits are nominally 'off' . The older wylex domestic  designs are another case in point

However,  as per Adrian above, above any activity  that has the potential to expose live terminals should not really be recommended to unskilled/incompetent persons who cannot accurately recognize the risk.

The single meter tail is ideal, as it is outside all the containment, almost anything else involves opening things up.

I'd restrict the advice to suggesting that it is a DIY task only in those cases that do not involve opening up a distribution board, or anything that opens with a key or screwdriver. If tools are needed then it falls into the 'if in any doubt take the advice of a competent person '  category..

The US is more fussy about who is allowed to do what, but less strict on the testing aspect.

Mike

I agree - it seems like an odd design. All the domestic type energy monitoring CTs I've seen have been intended to be installed on an insulated & sheathed single-code cable outside a CU. (This kind of thing, just as a random example https://uk.rs-online.com/web/p/energy-meters/8724666 - same with the OpenEnergyMonitor https://shop.openenergymonitor.com/100a-max-clip-on-current-sensor-ct/ )

Legal wise, in any kind of work situation the Health & Safety at Work act would apply - specifically the Electricity at Work Regulations. As usual don't expect anything simple like 'must hold xyz qualification' but more general principles like "No person shall be engaged in any work activity where technical knowledge or experience is necessary to prevent danger or, where appropriate, injury, unless he possesses such knowledge or experience, or is under such degree of supervision as may be appropriate having regard to the nature of the work."

  - Andy.

It is in my view very poor practice to encourage non qualified persons to fit these devices in a live consumer unit.

Most of the conductors within a consumer unit are SINGLE insulated and best not handled whilst live.

The condition of the wires is unknown, old and perished rubber insulation or heat damaged PVC may be present.

The standard of pre existing workmanship is unknown and any manipulation of existing connections mat result in loose connections etc. Many real world consumer units are much more congested than the one illustrated, and considerable disturbance is likely.

An unknown amount of live metal is exposed in many consumer units.

So whilst there may not be any specific law prohibiting these devices being fitted by a non qualified persons, it seems very unwise indeed to promote or encourage such use.

Similar current transformers fitted EXTERNAL to the consumer unit, to the meter tails are much lower risk and could reasonably be fitted by a non electrician. I would however consider it good practice for the person fitting them to have SOME BASIC training in order that they may recognise clearly defective meter tails.

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?

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.

AJJewsbury said:

Legal wise, in any kind of work situation the Health & Safety at Work act would apply - specifically the Electricity at Work Regulations.

Agreed. That would apply just as much in domestic premises as commercial ones because the installer would be at work.

If any equipment is opened, it should generally be made dead beforehand (R.14) and whoever does the work must be competent to do it safely (R.16).

Clearly, they apply only in UK.

I would suggest you said something like 

'a simple job for any competent person' or 'a simple job for an electrician'

I think that is the truth of it too

I have just installed some split core CTs, mine are all 5a, so will burn out if left open circuit, I guess yours are not that sort, and are modular. The metering equipment needs a supply, and on a 3 phase supply, you arent going to be able to just plug it in, it will need a 3 phase supply fed from a board, and that definitely is a job for an electrician. 

They never look quite as neat as you envisage either!

Suggesting that any idiot can fit them is just going to open yourself up to ridicule at best and a court case at worst. In that board in the photo, there are plenty of opportunities for an idiot to electrocute themselves, loosen something which might set on fire later, etc, etc.

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...

Just to add my ten penny worth, if your target customer is the man on the street then I can say that I've never met a client who would even dream of opening a CU, never mind pokiing about inside, thank goodness. And as Dave said, they generally don't look like your example, more like red and black spaghetti, and it'll be even more fun when the CU is populated with RCBO's