Learn Electrical Reference Methods, Installation Reference Methods
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The recording and reporting of Electrical Reference Methods and Installation Reference Methods are an essential requirement on Electrical Installation Certificates following any new work of an electrical nature and required on all Electrical Installation Condition Reports after an electrical installation safety check .
But just what is method A, B, C etc? What is method 100, 101 for instance for twin and earth cable?
Follow the guidance in this video and you will learn the most effective and easiest way of understanding and remembering the reference system for electrical installations.
Instead of spending valuable minutes (or hours) trying to decide on the correct letters and numbers to enter, this video will show you how to quickly and easily cut through all the confusing information and enter the correct details in an instant.
Another of those “black art” pieces of information that will stay with you throughout your working life.
Easily learnt, never forgotten.
SEE ALL - To view a list of all our LearnElectrics videos, click on the link below. There are many videos on many electrical topics including Installation, Part P, 18th Edition, Testing, Certification, Lighting, Sockets, Ring Circuits and much more. kzhead.info/tools/YaJQnpO4XAp0yCgqzMkmfA.html
I was really finding it difficult in memorrising these methods, watching this video has made it a breeze. Dave is a God send. Thanks
So happy to help. Its easy once its pointed out, until then its a black art. Enjoy.
One of the absolute best channels on KZhead, THANK YOU!
Brilliant feedback, thanks. Dave.
This is great, as is your entire catalogue of videos I've watched so far. Thanks very much.
Thank you for the very positive feedback. It is truly appreciated. Dave
Another fantastic upload, many thanks!
Thank you too. appreciated.
Fabulous saves a lot of time. Good sound advice. Thank you
Happy to help Sean, glad you liked it. Thanks for the positive comments. Dave
This is making such a difference. This was always the hardest part for me but this helps it make much more sense.
Glad it's useful to you. Thanks for watching, lots more to come. Dave.
Nice work. Yet another bite sized chunk of understandable information. 😋
Thank you John, appreciated. We try to do one video on just one topic.
Great work thanks you so much🎉🎉
Most welcome, thanks for watching.
Brilliant video. Really like the detailed explanation as to why we have reference methods
Thankyou, so glad it was useful and thanks for watching. Dave.
This is EXCELLENT!
Thanks Abdul. There are nearly 200 videos to watch. You can also see a list of the videos and search for a particular question/help at LearnElectrics.com. Thanks for watching.
Thanks, it’s really helping me for 2391!
Thank you. Dave.
Fantastic and very useful video thanks mate 5star
Thank you so mush for the positive comment. It is really appreciated. Dave.
Thank you again
Thank you too Darren, appreciate the support. Dave.
very nice video....great work...thanks.
Thanks for the feedback Bara, appreciated. Dave.
Very useful thank you. I have a question if I may.... in my new build loft I have a spaghetti mess of 1mm lighting cables that don't follow the roof trusses, they just go directly to each light fitting or switch. They go up and over each roof truss they pass and then drop down to rest on the plasterboard ceiling beneath 270mm of insulation. Is this reference method 101 or does the entire cable run have to be touching the non-insulation surface for its entire length? I fail to see how thats possible in a modern loft though where there are roof trusses in the way. Additionally, some of the cables are so tight that when they pass over a truss they don't have enough slack to get back down to the plasterboard before rising up over the next truss. The insulation has simply been laid over them in this case. Is this classed as reference method 103 then, although they do have some limited contact with the truss timbers they are strung between? Thank you
Its reference method 101 if it is in contact with a plasterboard ceiling or roof trusses and the insulation exceeds 100mm. The worst case reference method applies to the whole cable, and reading your notes this will be 101. Dave.
“Hello and welcome to Learn Alphabets” Lol I love it
Thank you for watching. Dave.
Thank you 🙏
Glad you enjoyed the videos lots more to come.
Excellent videos
Thank you very much, appreciate the great comment. Dave.
Hi great video... Quick question? What would be the difference between reference method A and C in terms of a Flat Twin and CPC clipped to a chase then plastered in? Ref A says within building materials and Ref C says chased in? Also, what about a circuit tgat contains many reference methods? Chased in, then through a plasterboard ceiling, then in trunking and finally to, let's say an IP rated socket outside? Thanks
This sounds like Ref C - chased in. Where there are several methods always rate the cable for the worst conditions, then everything else will be ok. On the certificate you can write in all methods e.g. C, 101,B or just the worst case, the one that you have selected the cable rating against e.g. 101 The important thing is to leave sufficient information on the certificate so that anybody following you can work out what is happening and why you chose certain cable sizes. Hope this helps. Dave
Your videos are put together better than anywhere online or in the classroom How would you class a cable that's clipped direct then passes through stud wall with insulation? The wall and insulation is worst case so would you class it ref 100 instead of clipped direct? Thanks sir.
Yes, always use the worst case for the cable conditions. Take a look at this video on condition codes. Dave. kzhead.info/sun/jLWpdKh6poymaps/bejne.html
@@learnelectrics4402 Thanks bud appreciated 👍
Great video
Thank you Vince, appreciate the feedback. Lots more videos to choose from and many more on the way. Dave.
very very well explained thankyou. quick question. what if the supply is wired through multiple reference methods? do you add all in the test she or just the majority of the circuit?
I will be doing a video on that soon. You multiply them all together, which men]and the cable needs to get bigger.
@@learnelectrics4402 thats great but i mean more about writing on the test sheets. can you group the reference methods in same box. lie a b and c in one box
Yes, you can just list them. It's your test sheet, if you feel you need to add extra info, then do so. Good luck.
@@learnelectrics4402 thanks very much. i appreciate your help and quick reply. your videos are fantastic.
Hi, as has been stated many times your videos are excellent. Just one question, are reference methods 100 to 103 only applicable to twin & earth, or are methods A to F also applicable? Many thanks.
!00 to 103 apply to twin and earth because of the type of construction and the type of installation methods, ceilings, walls etc. in domestic properties, perhaps in shops and small units etc., the sort that you wouldn't normally get in a big factory for example. Methods A to F apply to all the other drawings in the appendix which are more applicable to industrial work. Hope this helps. Dave.
@@learnelectrics4402 Thank you.
Thanks 👍
My pleasure, thanks for watching.
Thank you
Glad you enjoyed it Ali.
Hi! I have found this, regarding Method E and F. Is this correct? Reference Method E - Single-core on perforated cable tray or ladder rack. Reference Method F - Multi-core cables on perforated cable tray or ladder rack.
Have a look at pages 438/439 in the Regs and have another look at the video. Hope this helps. Dave.
Hi Dave. I've got cables going through middle of joists (drilled hole) in a garage and then clipped onto wood, and also clipped onto brick. What is the best classified reference method?
Sounds like clipped direct to me. If its twin and earth, look at Table 4D5 on page 456 of the Regs book. Reference method C - clipped direct. Dave.
@@learnelectrics4402 Thank you very much. I did think it would be reference method C too.
I’m planning to wire up my garage with PVC singles in a plastic flexible conduit. If I use a radial circuit and 20a mcb, would this be safe? If the wire heats up to 24a in the conduit, it will trip the 20a switch anyway?
Guj, you need lots more information before you can decide on anything, Such as cable size, cable length, how many wires in the conduit etc. And no, 24A will NOT trip a 20A circuit breaker in a safe time. You need to use the data in the On-Site Guide. Take a look at the video on the link below, this will be really useful to you. Lots more info and links to videos on our website at LearnElectrics.com If you're new to electrics, always seek good local knowledge from a competent electrician that can help you plan the work. This is the video .... WHY MY FUSE BLOWS AND WHY 8 AMPS WILL NOT TRIP A 6 AMP CIRCUIT BREAKER kzhead.info/sun/eb5vXdOjmZmOfqc/bejne.html
What is your opinion of cavity wall insulation beads(not polystyrene that affects PVC on cable) where existing cables are already in the cavity that is only 2 inchs wide. Even if the cable was in the middle of the cavity it would be max one inch of insulation max between it and the brick walls . Would it be better to remove cables and put in round plastic trunking inside the cavity ?
The plastic trunking will still have insulating properties, and it will then be inside a thermal wall. your choice again.
@@learnelectrics4402 Yes , i agree , It would not be correct . Thank you.
What is a thermal wall - for ref A? If I have a standard bulding brick external wall with cavity insulation and T+E chased on the inner with pvc or metal capping and plaster is that A (2) or C (58)?
Have a look at page 436 in the regs book. If item 57 or 58 apply, then it will be Reference method C. Hope this helps. Dave.
what would be the reference method of cables clipped to a joist or lying on plasterboard ceiling in joist void without any insulation? I would assume clipped direct but it’s not necessarily clipped on a wall.
Have a look at Table 4A2 on page 433 of the Regs. Pictures of each type are shown.
@@learnelectrics4402Have had a look and still can’t see anything regarding without insulation, the closest thing i can get to cables clipped on joist without insulation is Method 100, being With Insulation not exceeding 100mm.
Can a reference method change mid cable run? Let's say you're in 100mm loft insulation and need for example 6mm2 cable. If then it comes through the ceiling to an isolator, then out of the isolator it's clipped direct. Can you reduce the size of the cable then?
The cable size must suit the conditions at each point, so yes you can change sizes where it comes out of the isolator.
@@learnelectrics4402 Thankyou for your reply.. I have learnt so much towards my qualification from you. Respect 👍
What if you get flat sheathed cable on tray? There is no data in table 4D5 for reference method E. But there is current carrying data on method E for ''multicored cable''.. Can flat twin and earth be regarded as a multicored cable ? if T=E in on tray. can I use the current carrying capacity data of multicored cable?.. or just stick with the data for flat sheathed cble with only goes up to method C..??and just use capacity of method C with is safer than method E anyway. I've got the design exam in two days. Thanks
Twin and Earth on a tray is always confusing, but it is a multi-core cable and can be prone to be packed with lots of others on a tray. Reference method C is clipped direct cables in/on walls.
*Question: If I have a ref method of 100 do I still apply the Ci rating factor in the cable calculation?*
If you look at page 409 in the blue Regs book, 2.5mm T/E for example says max current is 21Amps, that is your Ci applied, now calculate the other factors that migt affect it starting with 21A. Hope this helps.
@@learnelectrics4402 Much appreciated.
What would ref be clipped under floorboards C or B in a void ? Always get contrasting views. If it is B then do you refer to ref B cable current carrying capacities?
That's always a good one. If the void looks like the ceiling pictures for methods 100 to 103 then some folk stick with them. But if its a small void with no ventilation, perhaps B is better. And also consider what current might flow. If it was a 9kW shower I would certainly derate it. If its a 6A lighting circuit perhaps not. The size of breaker is doing the derating for you.
Just a quick question Sir. Ref method C for 2.5mm twin & earth chased in and plastered in, the current carrying capacity is 27Amps. What about heat dispensing?
Its been allowed for. Have another look at the video and it will make sense. Thanks for watching and lots more to come.
@@learnelectrics4402 thanks a lot Sir
You are welcome.
Where a cable drops down in a cavity wall would it be bad to cut this off and just connect a larger cable in its place where it runs through the cavity wall insulation. Would it be bad to have these connections in the attic ??
Nothing in the regs that stops you doing this, you are installing cable suitable for the conditions at each stage. But make sure your connections are good and accessible. Also, it might cost more in time and materials to do that, rather than just run the bigger cable all the way through and have no worries. Your choice if it is safe.
@@learnelectrics4402 Thank you very much for your opinion. I will check the existing cable suitability first. Its the external hot water tank circuit which gets the most use in the house. The cooker circuit is on an internal block wall so does not use the cavity. I am not overly concerned about the wall socket cables as they do not get prolonged use ie kettle or hair dryer etc
What reference method is T&E cable in a conduit buried in a non thermal insulated wall?
We wouldn't normally put t/e in conduit. I would go for worst case 103 if its already built. Use singles in conduit where possible.
@@learnelectrics4402 I done a recent rewire whereby open ended conduits ran from the loft to the socket/switch boxes in the wall below, all done in T&E.
if cable is run through a conduit inside a concrete wall what installation method do i use?
Have a look at Nos 41 and 42 on page 435 of the Regs. One of these methods might be what you are looking for, Thanks for watching. Dave.
What would be the reference number for the following T & E cable: (1) A cable laid over a plasterboard ceiling without any insulation (no clips) (2) A cable within a dividing wall. Plasterboard each side on timber studding. No insulation. No clips. (3) A cable behind kitchen units and supported by the floor. No clips.
Kevin, determine the three reference methods for each scenario and choose the worst one. If the cable is sized correctly for the worst case it will be good enough for the other two. Without seeing the job it is difficult to say but it looks like 1 and 2 might be Ref C and 2 is either Ref C or Ref B. Look at pages 383 to 392 in 18th Edition Regs. that will help you to make a decision. dave.
Thanks
You're very welcome.
@@learnelectrics4402 I’d like to say what a brilliant video this is not just for learners but also older electricians too. it is confusing in this type of situation to select the “worst case scenario” (especially on an eicr, as you don’t know how the cable is run) as far as current carrying capacity goes is it simply a case of a is best and f is worst, when choosing which one to select to go on the eicr?
Usually put the reference method for cables in containment or thermal insulation as they will not lose heat the same as those clipped direct or in free air, so yes, put the worst case on the certs.
When it comes to ring mains do you half the rating of the MCB since it has two paths to travel through? When I look at T&E on page 409 of BS7671 a 32A ring main would require 6mm cable for method 100#?!
No. MCB size and cable size have to match against the load and the type of circuit. Take a look at our video. Ring and Radial Circuits What are the Differences kzhead.info/sun/aauHkpWLineghJ8/bejne.html Ring circuits also require extra testing and we have a video for that. Whatever you do, remember that electricity is dangerous. An incorrect installation can causes fires.
Domestic its Refrence Method B, unless it's armoured its C, in real life you don't get paid to investigate and start cutting plaster boards or going through walls finding out how the thickness is or how much they are not exceeding. You can not go and do these reports cutting through plaster boards and walls to find out how cables are sitting or they're mm not exceeding.
Thanks for the input Raj. Appreciated.
My lecturer send this
Glad you both enjoyed the video. Many more to come. Dave.
Concrete trenches are excavated by an excavator and what does excavator begin with? 🤔🤔🤔
I like that. A great way to remember that one. Thanks. Dave.
Thank you 🙏
You’re welcome, thanks.