I would consider handing a candidate in the UK a BS 1363 Plug, a length of flex, and an appropriate selection of tools and asking them to wire the plug, and then present the finished task.
This quick interview task would allow you to see a candidate’s ability to ask questions if their knowledge was lacking, it would also allow you to assess their ability to use tools and show the quality of their work.
For those of you not in the UK, the wiring colours are enshrined in IEC 60446, which since 2004 has mandated that Live is Brown, Neutral is Blue, and Protective Earth is Green/Yellow. (while not used in single-phase plugs, IEC 60446 mandates that Line 1 is Brown, L2 is Black, and L3 is Grey).
The fuse in a 3 Pin BS 1363 plug (BS 1363-1:2023 – 13 A plugs, socket-outlets, adaptors and connection units. Re-wirable and non-re-wirable 13 A fused plugs. – Specification) is part of the requirements and is controlled by BS 1362 (BS 1362:1973+A3:2021 – General purpose fuse links for domestic and similar purposes (primarily for use in plugs) – Specification). The mandated colours for the fuses are 3A red and 13A brown, with all other fuse ratings being black.
BS 1363 plugs and sockets are rated for use at a maximum of 250 V AC and 13 A, except for non-rewirable plugs which have a current rating according to the type of cable connected to them and the fuse fitted. The rating must be marked on the plug.
Placing a non-compliant plug onto the market in the United Kingdom is an offence under the “The Plugs and Sockets, etc. (Safety) Regulations 1994”, which was put in place to alleviate concerns that consumer safety was compromised by the counterfeit and unsafe electrical plugs and sockets being placed on the UK market When working for CASS Industries we saw a number of these come in from Chinese suppliers.
Interview Response
Job interviews have reconvened at my brother-in-law‘s works to find a new electrical engineer. All of the 20 candidates must have a master’s degree in electrical engineering. Whilst interviewing them he asked them to wire a 3-pin plug to check their abilities, which has thrown up this little gem. Luckily the position has now been filled but thankfully not by the creator of this masterpiece.
Chris Jane – Facebook
This photograph and associated paragraph were posted on Facebook by Chris Jane. Quite a few of the responses on the image claim that a master-level Electrical Engineer doesn’t need to know how to wire a plug… but the original post states Electrical, not an Electronics Engineer…
Either way, I feel that this is a valid Interview question, as even if you don’t know the correct wiring scheme, there is nothing to stop you from asking the interviewer. This one simple task shows up your approach to safety and tool usage.
133 thoughts on “BS 1363 Plug as an Interview Question”
I guess it depends what position they were recruiting for but its a very sobering image. They used to teach plug wiring in school once.
It’s always useful to have a fuse on the earth for … reasons that escape me for the moment. /S
It comes to something when people comment that even an engineering degree doesn’t require to know how to wire a plug .. how stupid is society becoming, I’m sure both my Grannies would have known how to wire a plug ! On top of that I would not let this candidate make a cup of tea looking at the state of the wiring never mind where they connected them to ! 😂
I don’t mind that a graduate doesn’t know how to wire a plug. If they had asked for information and help would have made them a much better candidate
it’s a sad state of our society now with the lack of practical skills. I did an original reply which I did say exactly what you mention that admitting you don’t know us more important (however I changed it). However, we are talking about an electrical engineering graduate not someone with another discipline ! I also understand that their position may not require to carry out the practical skill of wiring a plug … but they must be aware of what cables go where !!!
I’m not blaming the youngsters I’m blaming society for lack of training and structure to such important jobs in our country.
Totally agreed Colin. We has a new guy with an HND in Electrical Engineering. I asked him to put a 13A plug on a cable.
First he told me he was an Electrical Engineer and that was an electricians job. When I insisted, he asked for a pair of scissors to cut the cable !🙄🙄🙄
Ouch… that is the wrong tool
Aye, but your Grannie’s would have made it all off with the ubiquitous “butter knife” 🙂
…and used “bell wire” like I’ve found in many an old person’s house for the wiring of Bedside table lamps, and on a 13Amp fuse!
Apparently Colin they asked ChatGPT to do it for them but their laptop sat there and didn’t do anything. It didn’t even look at the tools provided never mind pick one up!
I don’t think the level of qualification has anything to do with lack of practical knowledge & skills, except to say that a candidate without basic hands-on skills shouldn’t be allowed to join a higher-level electrical engineering course perhaps?
so the interview successfully filtered out an unsuitable candidate.
it’s not the practical knowledge that’s the worry … they may be designing an electrical system ! At least get the correct cables in the correct place ! Society has allowed the layers of workers to disappear from craft to academics in engineering. We need clever academic people as much as practical craft and all those in between.
agreed! 👍
BS7671:2018+A2:2022 Wireing Regulations Bristish standards.
Designer, Installer,Tester, and Commissioning Engineer.
ONC, HNC, HND, BEng, MSc, PHD, Professor.
No natter what your Qualifications, you should stay up to date with the BS761,and take the Exam around every 3-4 years. Compulsory for all.
I only have 17th edition. Digital copies of the regs are hard to get hold of as BSI don’t hold the copyright for all the annexes
BS7671 still won’t teach you how to wire a plug, just select the correct fuse size for the cable, so not quite. Competence is a mix of skills, knowledge and experience. When I get the time I will update from the 17th but not critical to my business.
oh boy, you missed out on the UK demographic map for lighting strikes, 2018 first edition Blue Book. You’ll never know what calculations you’ve missed out on, especially if you don’t know how far it is to your nearest substation! People who did that level and read this will understand that bit. I was so pleased when Rev 2 came out! 😂
I’m intrigued, was going to do some nuclear physics as CPD but this sounds far more fun 😁
I’d probably get stuck at Rutherford’s Atom!
Disagree.
The bog cleaner could learn and pass 18th edition, an electrician, it does not make him.
The exam is simply how fast you can index a paragraph in a book and select an answer on multiple choice.
If I wanted to know the type and size of cable and how deep to dig the trench, to run a supply to my shed, then it’s the go to book.
In reference to the op, a simple test of wiring a plug shows many things, safety, attention to detail, knowledge, practical skills.
You would hope common sense would prevail
Now that is scary.
I did an Adult Education Learning Course back in 2016. We all had to do a 15 minute interactive presentation. I supplied the materials and presented on how to wire up a 13A BS. 3 pin plug. The notes handed out were in colour.
2 out of the 9 fellow delegates turned out to be coloured blind!
One should never presume you know your audience.
I believe the colours were chosen to limit the risk of colour blindness being an issue
If you work on an old house never trust the colors …. measure first …. 😂
Where it gets interesting is when you have a 240v plug (of the variety without a neutral, as you might have for a motor) in the USA… then both L1 and L2 are hot. Appliances that use 240v, but that incorporate 120v loads, (perhaps a stove or clothes dryer) do now have a neutral, since it’s no longer permitted to use the earth ground as a current-carrying conductor, but older ones may not. Our service is “split phase” with neutral being the center tap of the transformer at the pole (or on the pad), so you have 120v L-N, or 240v L-L.
do the 120V loads need balancing on each side of the centre tap?
Yes, they’re supposed to be nominally balanced when the panel is laid out. It’s not perfect, but the electrical codes take that into account. Where it gets “fun” is if you lose the neutral from the power company… 120v loads can see much higher voltages than what they were designed for, depending on what’s connected where at the time.
This is indicative of what the wiring of the above plug should look like…
The tails should be of differing lengths (not indicated in that diagram).
Live should be the shortest, first to break if lead is pulled from the plug.
Next longest tail, should be Neutral.
Earth should be the longest tail and the last to break if the cable is pulled from the plug.
That is true, Also, the plug in the photo has a side entry Earth terminal.
This is incorrect as well its not the live actually called the line, neutral and earth
In the UK the nomenclature is Live not Line, its Line if you are in the US.
BS7671 Live Cable and Wiring
Also known as line or phase, this is the wire which carries the power in a standard low-voltage domestic electrical installation. It is colour-coded brown in the UK.
Ask anyone which colour is Live (not Line) and 90% of the people will reply with Brown. Ask them which colour is Line and only the people that have read BS7671 will reply with Brown. Live is the common nomenclature before the rules where homogenised with the EU and in my mind Live is more descriptive than Line even though I understand both. Plus the fact that the paper diagram you get on the bottom of a rewirable plug from a manufacturer such as MK will say Live not Line.
Because it’s usually black and white 😆
You can think of the hot side being BB whether USA or UK plug, black or brown are hot. The UK plug is the same one used where I am at in Qatar.
No that is incorrect, black isn’t used any-more in the UK but when it was it was neutral.
Not true. In the UK, it is red or brown. Black is neutral.
This image isn’t quite correct as all wires appear to be the same length. The GB plug is designed with the intention that the live wire is the shortest so if the cord grip and the terminals become loose and the cable is pulled, the live wire comes out first…
the fact you needed to post this is shocking! 😮
It’s a good idea to have more slack for the earth though. In the eventuality that the wires are pulled from the plug, the earth should be the last to email connected. There is a bit of room for this in the plug.
The Earthing conductor should be slack, this is because if the cable clamp on the mechanical protection fails, the live conductor will pull out before the Eathing conductor thus leaving the appliance still earthed but electrically safe.
– Hubby is an Electrician 🙂
Should also be a loop on the cpc (earthwire) so if the cable gets pulled the live pulls out first
you should do a pull test first cable pull out should be the live (Brown) the last the earth (green/yellow )
lol I love the fact you had to post a picture of what it should look like ….
I would’ve switched the brown & blue around. I guess I would’ve been wrong. Learning different wiring color codes isn’t something they ever taught us. Isn’t that really more of an Electrician thing?
Where do these people come from? who showed them how to do this.
I think the issue is that they are not…
BLue – Bottom Left
BRown – Bottom Right
Green is Ground or Earth (Always the Longer Pin)
Just wow. + did they even mention the defect to the blue sheath? I’m guessing it’s a no. 😎⚡
I am impressed by the wire being forced into the wrong side of the pin…
hmm Europeans might not be ‘Au fait’ with that type of plug, they have a more rounded experience in plugs. 😛
Don’t mention the war…
Australians have a flat pin affinity, and no fuses in plugs.. We do however have every cable colour scheme used globally..
I was taught how to wire a plug in High School even though it wasn’t on the curriculum as the teacher thought it too important a life skill for everybody.
I now have lots of respect for him doing that cos looking back, it was the only time I was taught to wire a plug, HOWEVER, I was taught about mains colour wiring in my first college course which was a OND BTEC Electrical and Electronic Engineering which would have allowed me to recognise what the L, N and E markings on the plug meant.
if he didn’t include this as part of the test, you could expand on this test and make it a low wattage item on the other end rather than just a cable, a 3A and 5A fuse in a packet with the tools and see if they replaced the fuse with the right value for the application.
Would be interested to find if anyone wiring correctly then overlooked the fuse rating.
If you can’t do the basics – then how on earth can you be trusted with something difficult!
no pun intended?
Well spotted Matthew Oliver !!!!!!!!!!!!!!!!!!! You are a real “live” wire……….
just flexing my brain muscles
BRown on the Right,
BLue on the Left,
And the stripes down the middle.
Unless you’re colour blind in which case touch nothing and put the screwdriver down!
This is quite interesting. I didn’t know the colors in your country.
In college I learned that in the US (and others) line is black because in our society black signifies death. In other countries, line is white (think clouds and heaven). Imagine paying $27,000 to learn these facts!
Why is your earth wire insulated? It has a purpose being bare.
I’m also wondering why earth are insulated. Maybe its sheath is just a convenient way to pack the cable and to label it ?
Well if anyone asked me that in an interview without forewarning me I’d wire it and then end the interview. And if I was forewarned I’d probably not go. The reason I think this is that this stuff all varies by country and jurisdiction. UK is quite odd and kind of strange by world norms with that local fusing and the really big contact pins. And the comments about insulation on the earth conductors are telling about philosophy of electrical distribution systems. If you are making a global product then testing this type of local market knowledge is a bit of a trap. And if you don’t have technicians to do wiring then it’s likely that people who are well trained in what you need from a masters trained engineer will give the company and a job a miss. Engineers aren’t technicians or electricians. If you use them as that then you’ll get what you get. Did your HR department clear you posting this? And does UK employment law let you post this?
If you were going for an interview in the country you are interviewing in, and presented with a plug from that country.
As stated in my post. It was taken from somewhere else. I can’t see why either HR or UK employment law would take issue with my posting an image.
However I will be adding this test to my assessment of people who I interview.
Rewirable plugs come with a paper insert that show cut and strip lengths and a diagram showing the correct wiring
I worked in the UK and never knew how to wire a UK plug. They are just odd and everyone outside the UK knows that. And no one expected me to wire anything. I designed power electronics for global use while working in UK companies. Seriously though, what you have posted is not doing your employer brand any good! And it’s unlikely that your HR people will be happy about you doing this. Ask them on Monday.
Sure there is a lot of variations between countries and sure we can expect minor errors from candidates without forewarning. But here the was a big error gross and fatal. Knowing that the earth is yellow-green and where it connects is basic knowledge to be alive. But I agree that the proper position and colors of live and neutral can be confusing.
Yes, it is patently unfair because of the locale business.
But in an interview when I am thrown a problem I do not know the solution to, then I tell them that and how I would go about solving it.
I am also surprised Natasha Cleeve at how many time I am approached for electrician jobs, where clearly the recruiter does know the difference between electrician work and electronics work.
As I mentor young people, I am amazed at how many do not even know the line voltage in the US (where we are) or even own a screwdriver. Bonus points for a screwdriver and a DVM.
Do I win bonus points for full set of screwdrivers, DVM, knowing L1/2 to N is 110 V AC @ 60 Hz, with 220 V AC for L1 – L2 split in the US.
Yes, I will grant you the Valuable Bonus Points. A certificate suitable for framing will be forthcoming ;<}
I was always told these colours were selected as there is no type of colour blindness that will result in these wires becoming confused. I don’t know if that’s true as I was an apprentice at the time so as you can imagine there were lots of windups 😬!
I am somewhat colour-blind and these colors are no trouble for me. It’s sad, though, because in the housing there is a big letter “N” where the earthing wire goes.
thanks 🙏 maybe there is some truth to that color selection! I was shocked when I came over to the US and found black was hot/live and white neutral in residential wiring.
Seems to be a lot of doubt regarding the suitability of this as an interview question.
Of course it is suitable.
I don’t want an instrument or control panel designed, or the test/prototype units made, to this standard. It’s not just that the candidate got the colours wrong, it’s that their standard of work is shit and they appear to not care.
A lot would have been saved by saying “I’ll have to look up the colour codes for X country” but still doing a neat and competent job using random colours. That picture is neither.
I would value “I don’t know, let me look it up” above some one getting it right first time.
I would value either, but the “look it up” approach does imply a sense of self checking which is very valuable in complex wiring scenarios.
But that is neither
not only that but the termination points are clearly indicated with LNE- if you can’t follow this you can’t follow schematics
to be fair not everyone knows the colour codes. I always used to misremember them when I was young. Checking costs a few seconds – doing a crap quality wiring job can cost a lot more.
Murdo McLeod although I see your point the original post states electrical engineer… To know the basics is fundamental in my eyes… Unless of course there is a underlying problem… Poor eye sight/colour blindness however this should be stated…
Yes, and they change e.g. UK codes did change in 2004 or 2006..
exactly, although the plug codes haven’t changed since we moved from the old 3-pin round to 3-pin square.
My gripe is the quality – I could do better with a rusty penknife.
Not to mention the broken insulation at the strain relief of the blue wire.
the insulation has been compromised. Exposed conductors. Incorrect terminations. Practical score 1/10
An interview is designed to allow you to determine the best person for the job – this test would certainly go a long way to help with this goal. I’d get them to do a RJ45 and a BNC as well.
I always have issues with RJ45s
A good test then – always employ people with the right skills! Crimped BNCs do me in!
RJ45 is curel
Dam right it’s suitable
This is an entirely suitable interview test for an electrical engineer in the UK. My grandpa (ex-electrical engineer) used to say of some other engineers “I wouldn’t trust them to wire a 2 pin plug let alone 3”.
Well Murdo you kicked off something here!! It’s a good thing the test wasn’t 3 phase!!
Yes you are exactly right. This is just one example but “must be able to handle a skrew driver” is something many many masters degree graduates fail on.
I would not mind the candidate apologising for not knowing/being sure, pulling out their phone and looking up the procedure.
Use resources to do it right. Especially if the alternatives could lead to death.
Yes that’s the difficulty in testing in job interviews.
I also don’t know that many things by heart simply because I never needed to. I’ve become dependent on my phone and I think everybody has.
We would not be where we are now without this extra brain!
all the cables, but not in the right order
Shows that the university of life is still the best to get experience, surely an electrical engineer would design installs and where to run cables if you can’t get it right at least make it neat 😉
Just replace the fuse with a small nail and it’ll be absolutely perfect. 😂🔥
Absolutely appalling, but alas, not really surprising. Degrees are becoming ever less use. The person who wired this clearly had no idea, but ploughed on anyway. It is this totally misplaced sense of self-importance and self-assurance that gets me.
yup. Degrees are essential so that Engineers understand the principles, but the piece of paper on its own is useless. All graduates get told (nicely) “Your education is finished – but your training starts now – go and carry the toolbox for that Electrician for 3 months.”
I am basing what I write on being expected to teach Flight Mechanics, Control, Propulsion etc. to students who have no grasp of vectors, calculus, algebra etc., but grade inflation sees more and more “First Class” degrees being awarded. And the dangerous stupidity in the plug wiring picture chimes with what I see more or less every day in my univ. teaching job which I have done for thirty two years.
I learnt how to wire a plug in Scouts. Maybe the education of the electrical engineer with a masters degree was sadly neglected.
Wiring a plug is naff all to do with electrical engineering.
You’re thinking about an electrician.
An electronic engineer can claim this isn’t in their wheelhouse, but not electrical
I’m not an electrician or an electrical engineer but I can correctly wire a 13amp plug !
My dad thought me how to remember wiring a plug with this. bLue is Left. bRown is Right.
Work mate – every time I plug the extension lead in the power trips out
Me – give it here let me have a look
This is what I find when said work mate tried to fix it hahahaha.
I call BS, no sign of arcing/burning on that shiny copper.
I think the fuse/RCB/ trip would blow so quickly that it wouldn’t get time to burn anything.
I’ve found something similar on a friends ceiling lamp. She just changed the bulb and soon afterwards the lights didn’t work any more, but no breaker tripped. Some random testing of different bulbs and fuses in the dimmer switch (didn’t know those had a fuse, learned something), kept blowing fuses sometimes. Strange, because it worked fine for a year or so before the bulb replacement.
After some investigation it turns out that whoever installed the lamp just left 2 cm of copper exposed on each wire, so when you moved the lamp while changing the bulb it shorted. Then I went and checked all lamps in the apartment, which revealed the same mistake had been made on a few of them..
There’s your problem, you’ve asked someone with a masters to do a real engineers job.
Or at least a poor home DIY’er.
My highest qualification is NVQ and I teach people with masters how to wire control panels, program robots, write software and basic tool use.
Oh and show masters graduates how to use a tape measure 🙄
Only 3 wires and 7 mistakes.
1 & 3 – bare wire ( too long)
2 – swapped wires
4 – bare / cut wire
5 – wrong way round
6 & 7 – too long
Surprisingly they got the strain relief correct
Couldn’t tell if it was tight enough to do its job.
This was a great explanations of the issues!
I used to write user and service manuals. Not sure if anyone read them.
Can we have the score on the doors for this one from the first 20 interviewed
When I was 16 (I’m 68 now) I went for an interview for Post Office Telephones. Had to wire a three pin plug as part of the Practical section. Wired it perfectly, even left the Earth wire as the longest so it would detach last in the event of someone tripping over the cord.
Was failed as I’d held the plug in my hand all the time, if the screwdriver slipped I might have gashed my palm. Quite severe, a big knockback for a 16 year old.
I subsequently went for another interview in a different Telephone Area, and passed with flying colours. Workded for them for a total of 39 years.
yup – holding plug back in palm of your hand was a big no no 🙂
1 out of 3 isn’t a complete failure, is it?
I’m not sure that Neutral qualifies as “correct” judging by the termination and damage to the insulation 🤣
Yeah, it’s rough. Once the cover is on no one will know 🫣
not really correct either though. I’d say fail.
That’s the wiring of someone who displayed their contempt at the interview process.
Booksmart
Ok, so my question is why judge someone on something they’ve likely never done before? Probably that they never had cause to wire a plug in the past. Most likely that plugs came ready moulded and never went wrong if they’re under 30. Is that their fault? So why judge them on it? Did you show them what to do, let them practice and then ask them to do it? An electrical engineer is different to an electrician. I think you need to take a look at yourself, not the candidates you’re interviewing.
Don’t you think it’s a question of character on the part of the candidate. If you’re not sure, you admit it and offer to ascertain how to do it.
Depends if they were asked ‘do you know how to wire a plug?’ or told ‘can you wire this plug’.
It’s like taking mechanical engineering graduates and asking them to change a spark plug. I bet many couldn’t.
Well, in my experience employers are happy to work around their employees strengths and weaknesses, as long as they are made aware of them. It becomes very problematic when an employee can not be trusted to accurately self assess.
I would pick a practical trained guy with HNC everyday of the week over some guy with a degree. Now a PhD is another thing
bLue to the left, bRown to the right… degree completed