A retired Yank from Nebraska is coming to Edinburgh on a mission trip

[James]

You could start with a copy of this.

https://shop.------.org/requirement...tions-eighteenth-edition-bs-7671-2018-a2-2022

 

[James]

Sorry, the link to the official wiring regs in the U.K. seems to be censored on this forum!
search for bs 7671-2018 amendment 2

 

[loz2754]

The link @James was trying to post:

The IET Shop - Requirements for Electrical Installations, IET Wiring Regulations, Eighteenth Edition, BS 7671:2018+A2:2022

The IET Wiring Regulations is the national standard to which all domestic and industrial wiring must conform. BS 7671:2018+A2:2022 incorporates changes from the first amendment, published in 2020, regarding Electric Vehicle Charging Installations to provide greater guidance on embracing changing...

shorturl.at

 

[gskrusen]

The difference between UK & USA English is subtle and large at the same time.

For electrics here are a few that I can think of:

• panel = Distribution Board (DB) for commercial, or Consumer Unit (CU) for domestic work.
• breaker = Miniature Circuit Breaker (MCB) for small systems (to about 63A) or Moulded Case Circuit Breaker (MCCB) for larger stuff to 630A or so.
• GFCI = Residual Current Device (RCD) general case, or Residual Current Circuit Breaker (RCCB)
• AFCI = Arc Fault Detection Device (AFDD) here normally part of an RCBO (combined MCB & RCD)
• wire gauge = Cross Sectional Area (CSA) normally in mm^2 as actual area, not AWG (or SWG the old British style)
• ground = Earth, or Circuit Protective Conductor (CPC)
• hot = line / L ("live" strictly means current-carrying, so both L & N)
• cold = neutral / N
• wye = star

There are a range of other differences you will see. Obvious one is 50Hz instead of 60Hz, but most stuff here is 230V single-phase.

You do see 110V (as two-phase 55V-0V-55V) with yellow connectors on building sites for added safety, and occasionally 230V-0V-230V on rural properties, but generally if you need above 100A / 230V you get 3-phase here (400V delta / 230V wye) except for very large sites with private transformers where you might see 690V/400V 3-phase or event MV systems at 3.3kV or more.

The UK also likes fuses. Not just in our 13A plugs, but most installations have HRC fuses at the incomer and even MV motors, etc, often have fuses for fault protection. Related to this we have less of a focus on arc-flash energy limits, etc. Yes, it is still an issue on big sites but you won't see labels on everything warning you of energy levels as is see in the USA. It still pays to have a visor, gloves, etc, if working on big stuff as even with the energy limiting of fuses it can make for a VERY bad day.

As mentioned above, usually we treat light circuits as distinct from "power". Occasionally for something simple like a garage you might feed the lights off a 20A power socket circuit using a Fused Connection Unit (FCU) which is usually a switch and a fuse in the 3-13A region (3A typically for lights).

Normally we have the RCD/RCBO protecting the whole circuit (i.e. protective device is in the CU), not like the USA with GFCI/AFCI at the sockets themselves, but you do occasionally see RCD protected sockets here.

Due to our fused plugs and limited power demands it was common in old houses to maybe have just 3 circuits, cooker (30A), sockets (30A), and lights (5A) but today you would expect at least two light circuits and two socket circuits in most places, along with a few dedicated circuits like immersion heater, etc.

Also as @DPG mentioned we have a strong emphasis on testing, both:

• "dead" before energising where the insulation resistance is checked for obvious faults/damage at 500V (or 250V in some cases), and DC loop resistance of the live (hot) and CPC (ground wire) to prove both polarity and the fault clearing times will be met.
• "live" after energising to check the final circuit prospective fault current (PFC) / prospective short circuit current (PSCC) is within sane limits (i.e. that the MCB, etc, can safely clear a fault), the AC loop impedance 'Zs' is low enough for fault disconnection times to be met, and that RCD trip times are within specification.

Yes, this is the kind of stuff I need. I don't have to worry about the 3-phase. This is a single phase project. I will be getting the blue prints next month. Which will give me some time to study them. My other biggest concern is the testing the circuits. I am considering purchasing the proper testing equipment to do the tests. Having such a short window of 6-7 days to complete the project, I don't want to be delayed by the proper person not being available when I need him to complete the certs.

 

[gskrusen]

Remember to do the full suite of tests ( both live and dead testing). The required certs will need to be filled in as well.

Also recommend RCBOs rather than split load (aka dual RCD type) boards.

Above all, I hope you enjoy your trip to the UK!

Thank you so much. I agree with you that we are going to use RCBO's. Does the person doing the testing have to have a certification of some type?

 

[littlespark]

My advice, now, is get a local electrician involved.
One recommended by a church in the town you will be working in. One might be able to advise the work, and do the testing for very little cost…. knowing it’s for charity.

Buying and reading the regulation book, and on site guides is all well and good, but it’s nothing compared to the experience of a qualified electrician who has worked in the UK

Do you have a postcode of the place? I am too far, but there might be a forum member closer.

 

[pc1966]

Thank you so much. I agree with you that we are going to use RCBO's. Does the person doing the testing have to have a certification of some type?

As @littlespark says you are far better to get a local electrician involved early on as they can advise on what is needed and do the final testing, even if you do most of the work installing stuff.

In the UK the only legal requirement is to be "electrically competent" but if anything goes wrong then of course folks will be checking for proof that those involved were. Usually that is a combination of education/exams, practical experience, and having the tools needed (including the current wiring regulations book). There are some competent person schemes that serve to check and register folks (such as SELECT in Scotland, NICEIC, etc) to make it easier, but that is more common for domestic work than commercial/industrial.

There are two statuary regulations I can think of that basically cover electrical safety for most LV systems (some industries have specific rules that differ such as railways, mining, nuclear, etc):

• The Electricity at Work Regulations 1989
• The Electricity Safety, Quality and Continuity Regulations 2002

You can read them on-line for free but laws are written for lawyers. The Health & Safety Executive has some useful guidance to make it easier to understand and apply:

https://www.hse.gov.uk/pubns/priced/hsr25.pdf

That guidance is useful for point #9 (my emphasis) in the list:

BS 7671 is a code of practice which is widely recognised and accepted in the UK and compliance with it is likely to achieve compliance with relevant aspects of the Electricity at Work Regulations 1989

BS 7671 "Requirements for Electrical Installations, IET Wiring Regulations, Eighteenth Edition" is our "regs" also referred to as BBB (big brown book) and is equivalent to your NEC. It is not a legal document as such, and is updated and amended separately from the law which has not changed for some time. Note the legal guidance says "likely to achieve compliance" as the regs are the minimum standard and you can find odd situations where you might need to go beyond them to actually meet the law's goals for safety.

But in addition to the laws mentioned above you also have the building regulations and they differ slightly between 3 legislative regions of the UK: Scotland, England & Wales, and Northern Ireland. The Scottish ones are here, one for domestic properties, and one for others:

Building regulations

Monitoring and improving Scottish building regulations.

www.gov.scot

The whole thing is massive (550 pages as PDF download) and electricity is only a small section of what they cover, but the web version is not too difficult to find the related sections in:

Building standards technical handbook 2022: domestic

Scottish Government building standards technical handbook for domestic buildings, 2022.

www.gov.scot

But you get other sections such as 4.8.5 here covering switch locations:

Building standards technical handbook 2022: domestic

Scottish Government building standards technical handbook for domestic buildings, 2022.

www.gov.scot

 

[pc1966]

Just for the benefit of the OP or any others in their situation I thought of a few other differences worth mentioning:

• In the UK it is rare to see steel conduit in any domestic, or even many light commercial situations. It is seen in industrial and agricultural situations but sadly its not so common as it once was. For light duty stuff we typically use plastic conduit but that is more for show/appearance, or when putting cables in plastered walls, as it is not very impact resistant.
• We don't really have the equivalent of EMT. The steel conduit we use is all the medium gauge stuff (1.6mm = 1/16" wall thickness) often threaded, but you do get 'Conlok' accessories that makes life easier as ends don't need threading or rotation to install.
• You will see cables plastered directly in to channels in brick walls in many cases. I think it is a horrible practice and luckily it is not usually seen in Northern Ireland where they use plastic conduit (often oval profile so shallower grove needed) in the plaster to guide the cable.
• Mostly domestic wiring, and a fair bit of other types, is done in "twin and earth" cable (T&E). Or sometimes 3 core and earth (3&E) where multiple light switches are used such as top/bottom of stairs. It is vaguely like your Romex cable.
• Often T&E is PVC insulated to 70C max temperature, but you also get Low Smoke Zero Halogen (LSZH) types often seen in commercial settings where the fire safety regulations have been tougher and that is typically XLPE insulation good to 90C.

If you have some blue prints for the project maybe the electrics have already been designed and specified. If not safest option as above is to get the help of someone local. In most domestic cases the cable calculations are covered just by looking up the tables of standard circuits in chapter 7 of the IET On Site Guide (OSG) book. This is a small summary of key regulations and a few other good practice points, it is cheap so well work getting.

For a lot of situations you will find the following is used:

• 1mm cable and 6A RCBO for lights
• 2.5mm cable and either 20A (radial) or 32A (ring final circuit) RCBO for socket outlets
• 6mm cable and 32A RCBO for most domestic cookers (non-professional case allows significant load diversity)
• 10mm cable and 45A RCBO for electric shower

But the above choices are subject to the "installation method" (i.e. how much thermal insulation is present), if there are groups of cables over any significant length heating each other, and if the circuit length still meets voltage drop and fault disconnection requirements.

The OSG lists such details giving you max lengths and suitability for typical building methods/routes and for the majority of domestic / light commercial jobs it has the choice covered.

 

[littlespark]

We’ve not heard from OP since Wednesday, I think we may have put him off

 

[mainline]

Probably because of bbb making his head spin trying to understand it.

 

[Midwest]

Does seem unusual of a project of this type, not to use a local contractor? Although I have read of UK electricians doing such work abroad, but with all the differences in materials, installation methods, testing etc, I think it would make insurance and subsequent litigation, not worth the cost saving.