Service
Chemical earthing and lightning protection
Earth pits sunk and tested, bonding run back to the main terminal, and down conductors taken to ground.
Earthing is installed as its own scope rather than as the last item on an electrical bill: pits sunk to depth with the backfill compound around the electrode, conductors run back to the main earthing terminal, and the resistance measured and recorded rather than assumed.
Lightning protection is the same job carried up the building. The air termination, the down conductors and the earth they land on are one system, and it is fitted while there is still access to the roof and the facade.
How the work runs
-
While the ground is still open
Pits are set out clear of the foundations and away from the drains, and taken down with the rest of the groundworks. An earth pit dug after the paving is laid is dug through the paving.
-
The pit itself
The electrode is centred, the backfill compound is placed around it in layers and watered in, and the chamber is set to the finished level rather than left proud for somebody to break.
-
Conductors
Each electrode is run back to the main earthing terminal on its own conductor. The body earth, the neutral earth and the lightning earth are separate to the terminal, joined only where the design says so.
-
Lightning protection
Air terminations and the roof mesh go up with the roof, the down conductors run on the outside of the structure to their own pits, and both are fixed while there is still access to the facade.
-
Testing
Resistance is measured pit by pit before the system is joined, and again once it is. The figures are written down. An earth that was never measured is an assumption.
What decides whether it goes well
- Chemical earthing is bought for the backfill, and the backfill only works if it is watered in and the pit is topped up later. A pit left dry reads fine on the day and drifts within a year.
- The body earth and the neutral earth are separate electrodes for a reason. Tying them together at the pit puts the neutral current into every enclosure in the building.
- A lightning conductor taken to the electrical earth without a thought is a path for a strike straight into the panel room.
- Test chambers stay reachable. An earth pit tiled over cannot be measured, and an earth nobody can measure is only a claim.
Your project