Gas Engineers TB118 Compliance Testing Acutest Test Equipment

Gas safe technical bulletins (TB) give best practice guidance to Gas Safe Registered businesses and Engineers in a vast array of technical areas.  TB118 has been an industry bulletin for over a decade, it provides guidance on the safety precautions to be undertaken when working on appliances, specifically the safe electrical isolation of gas appliances.


Why is TB118 important?

Safe Electrical Isolation is an area of concern:

For Gas Engineers safe electrical isolation is more imperative than ever...

Many Gas Engineers have suffered burns, injury or worse due to avoidable electric shock over the years. When you hear such tragedy suffered by those unfortunate people working within your chosen profession… your ears prick up!

It’s Now Necessary to Prove Competence:

It’s now necessary that all Gas Engineers who apply for (or renew) their Gas Safe Registration are able to safely isolate the appliance they’re working on and can prove themselves competent.  

(from July 2020, consolidating from July 2025)

This can be achieved through:

  • Accredited Certification Scheme (ACS)
  • Group Competence Scheme (GCS)

↑ Updated - What Does the Latest Version of TB118 Mean for Gas Engineers?

TB118 was updated in January 2018. The updated Technical Bulletin includes new guidance in relation to electrical safety when working with electrical equipment, including gas appliances.

The 2018 revision still covers information on electric shock, and there are no changes to the safe isolation procedure however, important new detail was added:

+ Legislation
+ Creating safe test areas
+ Test equipment standards
+ Power supply earthing / Earth loop impedance testing
Safe to touch testing


TB118 refers to important legislation which must be recognised by both employers and employees, such as:

  • Health and Safety at Work act 1974 (HSWA)
  • Electricity at Work Regulations 1989 (EWR) 

EWR Regulation 13 and 14 are both directly mentioned. The fact that TB118 refers directly to these regulations shows how importantly this bulletin considers safe isolation and correct use of Lock Out Tag Out (LOTO) equipment.

Regulation 13: Adequate precautions shall be taken to prevent electrical equipment, which has been made dead in order to prevent danger while work is carried out on or near that equipment, from becoming electrically charged during that work if danger may thereby arise.

Regulation 14: No person shall be engaged in any work activity on or so near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless – (a) it is unreasonable in all the circumstances for it to be dead; and (b) it is reasonable in all the circumstances for him to be at work on or near it while it is live; and (c) suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.


Socket & See TB118 kits contain everything you need to comply with regulation 13 and 14. The VIP150 or VIP200 Two pole voltage indicators and SP200, SP400 proving units allow a correct safe isolation procedure to be easily carried out.

The Socket & See TB118 kits contain MCB LOCK, FUSE LOCK and PLUG LOCK - so however the appliance is isolated... the correct LOTO device is available! FUSE LOCK is compatible with all types of fused spur meaning unscrewing the face plate is not necessary.



Equipment standards

TB118 directly refers to BS EN performance and safety standards. This ensures that an engineer has the correct test and measurement equipment for the job.


  • Two Pole Voltage Indicators (for safe isolation) should be built to BS EN 61243
  • Non-Contact Voltage Indicators (for the safe-to-touch test), Earth Loop Impedance Testers and Proving Units should be built to BS EN 61010 safety standard.


All Socket & See TB118 equipment meet the required BS EN safety and performance standards. It’s ergonomic and robust design also means it’s suitable for use with PPE.

Socket & See DLM PRO used on a domestic boiler