Why a temporary continuity bond is fitted across a cut in metallic gas pipework, and the order of work.
Cutting into metallic gas pipework can be hazardous because the pipe may be carrying electrical current or sitting at a different electrical potential on each side of the cut. A temporary continuity bond manages that risk, and CCN1 expects you to use one. The order in principle is:
- Plan the work and identify where you will break into the metallic pipe.
- Before cutting, clip a temporary continuity bond across the section to be cut, making a clean metal-to-metal connection on each side using suitable clamps and a continuity conductor.
- Confirm both clamp connections are sound on clean metal, so the bond actually carries any current around the break.
- Carry out the gas work within your competence, leaving the bond in place throughout while the pipe is open.
- Remake the joint properly and confirm the pipe is once again electrically and mechanically continuous.
- Only then remove the temporary bond, in the reverse order, and carry on with tightness testing and recommissioning.
The reason is simple but easy to forget under time pressure: the bond gives the current a path around the cut so that breaking the pipe does not create a spark or expose you to a shock. It is a temporary measure for the duration of the work and does not replace the permanent main bonding of the installation.