An Electrician’s Q and A is all about helping to fill the gaps in your electrical knowledge and making it easy to access the info you’ll need. Helping you to become a better electrician!


Here is a selection of electricians’ questions which we are all likely to come across from time to time.

Please feel free to submit your own Q&As to be added to the list.

Online Training        City+Guilds Training

Wiring Regulations

TT Systems

TT systems. Bonding in bathrooms

TT Systems. Time-delay RCD main switch

Is a Ze of greater than 2oo ohms acceptable on a TT System?

TT Systems. Zs reading higher than tabulated

TT circuits require a disconnection time of 0.2 seconds

Why do TT systems require RCDs to achieve 0.2s disconnection time?

Why use 0.3s RCDs for TT when they don’t comply with 0.2 disconnection?


General Theory

How to convert KVA to Amps?


General Installation

Earthing & Bonding

Bonding on sink?

Bonding in a Bathroom?

Plastic Pipework


Inspection & Testing

Cables concealed in walls at less than 50mm deep. Which Recomendadtion code? Can I issue Part P & Installation Certificates for other peoples work?

Building Regulations
Hazardous Locations
Fire Alarms
Health & Safety
Insurance / Liabilities
More Q&As- Browse the Q&A articles.
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{ 29 comments… read them below or add one }

Greg September 15, 2018 at 06:43

Hi. Replaced sockets on radial from pvc to chrome accessories. When sockets not fixed to metal boxes the Zs readings on testing are good and RCD trips. But when fixed to the wall the Zs readings are very high (over 1000 M ohms) and the RCD doesn’t trip. Please can you advise what the problem might be.

Hi Greg
You may have a break in the earth conductor when you push the socket back to the wall. Good luck. Steve.

R D Nelmes Electrical June 22, 2018 at 09:21

Great post, very useful information as always.

Electrician In Honiton June 5, 2018 at 18:42

Can’t believe I’ve only just stumbled across your blog.
Keep up the good work.

Guelph Electrician November 22, 2017 at 14:10

Always interesting to compare the UK and Canadian standards, thanks for posting!

Digby July 23, 2017 at 14:35

Rcbos which take up 1 MCB way are not suitable for TT systems according to the manufacturer’s instructions is this because only the live is disconnected on fault or is there something else

Greg October 21, 2016 at 07:15

With RCD protection on a house which formerly got hit by lightning is it necessary to install SPD’s on the incoming main supply conductors?

A- Hi Greg

It’s always a good idea to have an SPD to protect against lightning strike at the mains intake. But as the likelyhood of a strike is so rare in the UK Surge Protection Devices aren’t often used in domestic installations. Insuance companies may request them if they consider lightning a high risk. More info here-

Richard September 17, 2015 at 15:15

When filling out certificates, what is the amendment date now in part 4 section ? Is it July 2015 due to Amendment 3?

Tamas solymosi August 31, 2015 at 04:49

Great Post! such a really useful info regarding electrician all about that , very informative info sharing by blogger. Love it this blog. – Putney Electrician

keith barnes June 3, 2015 at 12:13

Hi, I have an immersion heater circuit fed in 1.5 t&E with a B16 breaker and 30ma rcd behind it. All tests are ok but the cabling on the heater is getting hot at the point of connection on element and charring the cable. It will work ok for a couple of weeks and then trip rcd. any advice would be greatly appreciated. Thanks
Hi Keith
Sounds like either the 1.5T&E or the heater cable may be damaged by overheating. Or maybe the heater itself has a hairline crack and needs replacing.
You should be able to locate the fault by doing some insulation testing.
Also, if the immersion heater is 3kw then it should be fed in at least 2.5T&E.
All the best

Editor March 29, 2015 at 16:36

Hi John
You might find some useful info here-
All the best

JohnDee March 23, 2015 at 16:31

I have been doing domestic installations/testing for about 7 years but don’t have an NVQ or qualification – can anyone recommend the most efficient way for me to get recognised qualifications without having to start at the basics.

A-If you decide to study part-time whilst working then you can find courses that will give you a knowledge of basic electrical installation, inspection testing and electrical regs. These will be good to start you off, but you’ll still be need to pass further exams and attain the level of NVQ 3 on the path become a fully qualified electrician. Take a look at XS Online Training
All the best- Steve.

Electrician Farnborough March 22, 2015 at 08:38

Excellent bog, keep up the good work

Darren February 25, 2015 at 15:15

great to see electricians working together

Garry Goodchild February 24, 2015 at 18:00

I like your All information, specially that one wiring regulation !!!! Thanks For sharing with us,

Prem February 16, 2015 at 10:27

I am a registered electrical worker permitted to work in low voltage not exceeding 400A capacity in Hong Kong. Now I am in the UK, and would like to continue my career as electrical worker too. I would appreciate if I can get any information on converting my Hong Kong qualification to UK ? Is it possible to just apply for one or do I need to start learning from the beginning ? Thank you very much

Electrician Northern Beaches January 22, 2015 at 10:20

You have covered some very important electrician questions. Thanks for the information about online electrician training. This site is a great resource for electricians.

PowerstarLED January 7, 2015 at 11:45

Great post! Very informative, thank you for sharing.

Electrician School August 9, 2014 at 21:40

Nice Info.
Thanks for the article. keep the good work.

electricianforsydney July 24, 2014 at 12:24

Amazing,good information.

Kbultray June 28, 2013 at 09:26

Hi Leccys.

Does anyone have any ideas what to do when you find an electric motor and the name plate is missing ? The terminations are there, but may or not be lettered and that’s all the information there is.

shane June 16, 2013 at 06:26

hi im 47 living in Norwich working full time ive looked at becoming an electrician and have found a place that is called o.l.c.i are these people any good?

Hi Shane
I’ve not heard of them before but they seem legit from their website. I would recomend trying to get some reports from anyone who has already taken their courses.

You could also try asking on the forums-

Sie Bone February 22, 2013 at 16:52

could anyone tell me when the last amendmant to the regs was, just for these minor works sheets, cant seem to find it on the internet?

Editor November 17, 2012 at 17:26

Hi Terry
There’s nothing to stop you from doing electrical work in your own home if you are an electrician. But if you don’t complete the relevant test certificates and register the work with Local Building control for a Part P cert there could be a problem when you want to sell the house. The buyers and solicitors will ask for the paperwork for recent works. These should be submitted within 2 weeks of completion of the works.

terry mason November 17, 2012 at 12:09

I am a retired electrician and need to know can i do my own electical work in my own home please

sparks230 May 20, 2012 at 18:24

The company i work for wants me to start carring out electrical condition reports on there own propertys surely this is or could become a conflict of interest as they dont want to be proactive when it comes to bring things up to new standards.
Also I have had no new training with regard the new certificates

Editor March 12, 2012 at 21:24

Hi Tony. I’m not sure if the insurance company is correct but I know that thatched roofs are considered a higher risk. From an electrician’s point of view, I would recommend a full electrical test, connsidering the wiring is 30 years old. Many letting agencies insist on an Electrical Installation Condition Report every 5 years or on change of tenant.

Hope this helps.

tony marchant March 12, 2012 at 19:14

I live in a thatched cottage. I am a tenant. My contents insurance is now due. My insurance company are requesting an electrical certificate bs7671 in order to renew. Never had a request before for previous years renewals. Landlord cannot locate any certificates. House built some 30+ years ago. is the insurance company correct in requesting this information. The wiring in the house has not changed over the years.

peter houston September 13, 2011 at 19:42

is there a regulation for fixing back boxes with round head screws

electrician in swansea September 12, 2010 at 18:17

great information

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