Case Study 1: An Overheating Earth Cable, an Electrification Upgrade, and a Lesson Worth Sharing

Electrification is one of the biggest trends in Melbourne homes and businesses right now — heat pumps, EV chargers, induction cooktops, and battery storage all going onto switchboards that were designed for a very different, much lighter load. Most of the conversation around these upgrades focuses on circuit breakers and cable capacity for the new equipment. What often gets missed is the earthing system — and on a recent job, that's exactly where a real problem was hiding.

The Job: An Electrification Upgrade

The client was partway through an electrification project, adding significant new load onto their existing switchboard. Before commissioning the new circuits, a thorough assessment of the existing switchboard was carried out — because adding load to an older board isn't just about whether the new circuit fits, it's about whether everything already in that board can safely carry the increased demand.

What the Thermal Scan Found

As part of that assessment, a thermal imaging scan was run across the switchboard under load. One reading stood out immediately: the main earth conductor was running noticeably hotter than it should. In normal operation, an earth conductor carries little to no current, so any sustained heat on it is a red flag — it points to a conductor working harder than it was ever designed to.

Why It Was Undersized

Tracing the issue back, the cause became clear. The earth conductor had been correctly sized for the switchboard's original load decades earlier, but it had never been reassessed as extra circuits and appliances were added over the years — and the current electrification upgrade was about to add a meaningful amount of new load on top of that. The conductor simply wasn't rated for the total system it was now part of, which meant it was quietly overheating and degrading, well before the new equipment was even switched on.

The Fix

The earth conductor was recalculated against the full connected load — existing plus the new electrification circuits — in line with AS/NZS 3000 earthing requirements, then replaced with a correctly rated cable. The switchboard was re-tested and re-scanned under load to confirm the heat signature was gone before any new equipment was commissioned.

The Result

Catching this before the new loads went live meant the client avoided a switchboard fault, a potential fire risk, or a failed inspection down the track — all before it ever became a problem they'd notice. When it was explained what had been found and fixed, and why it mattered, the client was genuinely relieved and appreciative that the assessment had gone beyond just "does the new circuit fit."

The Lesson for Anyone Planning an Electrification Upgrade

If you're adding a heat pump, EV charger, induction cooktop, or solar and battery system to an existing property, it's worth remembering that these upgrades add load to more than just your switches and breakers — they add load to your entire earthing system too. A proper pre-upgrade assessment, including a thermal scan under load, is a small step that can catch a serious problem while it's still cheap and easy to fix.

●      Ask whether your switchboard has been assessed for total connected load, not just the new circuit being added.

●      Ask whether earthing conductors were checked and re-sized where necessary, not just the active conductors.

●      Ask if a thermal scan under load was carried out before and after the upgrade was commissioned.

Electrification is a great move for comfort, running costs, and emissions — but it's only as safe as the switchboard it's built on. A few extra checks up front make all the difference.