Temporary continuity bonding
Fitting a temporary bond before breaking into pipework or changing a meter.
This topic supports
- M07.2Use a temporary continuity bond correctly when breaking into pipework or replacing a meter.
Draft: this lesson hasn't yet been technically reviewed.
Whenever you break into metal gas pipework, there's a chance of current flowing in it. Cutting the pipe or undoing a union opens the circuit, and that can cause a spark at the very point where gas is escaping, or give you a shock. A keeps the circuit closed until the pipe is whole again.
When you need one
The law requires a suitable bond wherever it's needed to prevent danger, kept in place until the work is finished and permanent electrical continuity is restored (GSIUR reg. 10). BS 6891 is more specific: fit one during any work that involves removing a meter, breaking into the gas supply, or connecting or disconnecting any metal pipework. Fit it across the point where you'll connect or disconnect, or between the pipework and the fitting you're installing or removing.
The bond itself
BS 6891 recommends:
- at least 1.2 m of single-core, insulated, multi-strand flexible cable rated at 250 V AC or more
- a cross-sectional area of at least 10 mm²
- a robust clip or clamp firmly attached at each end, giving good metal-to-metal contact.
How to use it
- Isolate the electrical supply to any gas appliances connected to the pipework (see 7.4).
- Clamp the bond to each side of the union, fitting or section you're about to remove or connect, making good, secure metal contact.
- Do the work.
- Leave the bond on until the work is finished and metal continuity has been restored. If you're removing a section of pipe for good, make sure both remaining sections are bonded before you take the temporary bond off.
The same applies at the meter: bond across the meter before you remove it, from the inlet pipe to the outlet pipe.
Interactive artefact
Temporary continuity bonding
What happens to stray or fault current when a pipe is cut, with and without a temporary bond.
Will demonstrate
- The current path through metal pipework
- What happens when the pipe is broken without a bond
- Fitting and removing the bond in the right order
Planned. This interactive will appear here when it's built.
Sources: GSIUR 1998 reg. 10maintaining continuity L56 (2018) paras 160–161ACoP and guidance BS 6891:2015 8.3.4, Figure 7when, cable, procedure CCN1 Issue 16 §5assessed
Tutor notes
- Have learners demonstrate fitting a temporary bond across a union and across a meter on a training rig, describing each step aloud.
- Ask what could happen if the bond is taken off before the new section is connected.
- CCN1 §5 performance criterion 4 (4a–4e) assesses this practically: test, isolate, attach the bond, disconnect the meter, fit a capillary fitting next to it, reconnect, then remove the bond. Reg. 10 is knowledge item 14(i).