Number 3 on our list
Electricians Guide to the Building Regulations 5 Edition

Complete electrical works in a dwelling? This is the perfect publication for you to keep at hand. Its an A5 spiral bound book so fits nicely into glove boxes or tool bags.
This book covers the latest guidance on your electrical obligations with in a dwelling, third party verification schemes and covers relevant parts of the building regulations that you need to know.
From electricians to handy persons and all those who pickup screw drivers in between.Not only does this publication give great guidance on what you should be doing electrical within a dwelling its also the publication you need to undertake the City & Guilds 2393-10 qualification AKA Part P of the building regulations. https://mjelectricaltraining.co.uk/exam/part-p

Number 2 on our list
Electrical Installation Design Guide, 4th Edition

This publication from the IET is for electricians and designers who need to make calculations in their designs.
This step by step guidance makes it perfect for anyone studying electrical installations and design as it will help you understand the calculations needed for installation.

Fully updated to BS7671:2018 18th edition IET wiring regulations.

Number 1 on our list
NAPIT Code Breakers

If you undertake electrical installation condition reports AKA EICRs this publication from NAPIT is perfect.
A must for every electrician, trades person that undertakes electrical works and even landlords looking for an insight into the condition of their rental properties.

It has been written to aid contractors, inspectors and persons involved in electrical installations. The book was nominated as “Trade Tool of the Year” in the electrical industry awards 2018.
In our opinion if your undertake EICRs, Periodic inspections or electrical testing NAPIT Code breakers is probably the most important tool in the bag.
And its actually quite a good read!