The development of TB 118a

We go behind the scenes with Gas Safe Register’s Technical Team to look at why and how TB 118a has been updated – and what’s still to come.

During the periodic review of Technical Bulletins in late 2021, it was highlighted that TB 118 – Safe isolation of gas appliances – included information that was out of date and that it should be updated.

Given the importance of the Technical Bulletin – it is the most downloaded Technical Bulletin in Gas Safe Register’s online library – a committee came together to review and update it, with a membership of experts from both the gas and electrical industry. The process involved many meetings and long discussions into exactly what information should or shouldn’t be included.

It quickly became apparent that there was too much information for a single Technical Bulletin, and so the committee agreed that TB 118 should be split in to three parts:

• Part A: Safe isolation of single-phase low-voltage supplies

• Part B: Safe isolation of multi-phase and high-voltage supplies

• Part C: Earth loop impedance. The first part of the TB should be the most commonly used section and so TB118a: Safe to touch and/or safe isolation and proving dead on low-voltage single-phase supplies (below 1000v) was set in motion.

The committee spent many hours honing and perfecting the wording to be used, drawing on the immense knowledge and experience of its members. This wasn’t always easy, and there have been many changes and corrections before getting to the final version that is now available.

Once the committee had agreed on the content of the TB, it was decided that, for the first time, Gas Safe registered engineers should have the opportunity to give their opinion on it. Last autumn, Gas Safe Register hosted a draft version of TB 118a and invited gas engineers to view and comment on the draft, highlighting this move in Registered Gas Engineer magazine.

Feedack reflected

When all the comments had been received and collated, the committee reconvened to pore over them and updated the Technical Bulletin to reflect some of this feedback.

Finally, the Technical Bulletin was finished and ready, and on 1 February 2023, TB 118a Safe to touch and/or safe isolation and proving dead on low-voltage single-phase supplies (below

1000v) was published and uploaded to the engineer portal on Gas Safe Register’s website. But this isn’t the end of the journey. Alongside the regular Technical Bulletin, we’re trying something new. With the help of the committee member from NAPIT, an infographic style of the TB has also been produced. We are aware that the current style of Technical Bulletins can appear a little dated and so we want to know if it might be possible to update and breathe some fresh air into them.

We do need to point out that there are still considerations that need to be factored in around accessibility and that the original style may need to stay.

Look out for more detail on the infographic style of TB 118a in the next edition of Registered Gas Engineer ■