Short answer: commissioning thermography images new equipment under test load before handover, so installation defects are found while the contractor is still on site. An annual survey images the same equipment under normal operating load once the site is live, and compares it with that baseline. A data centre needs both: one to start clean, one to stay that way.
Commissioning thermography: what it is for
During integrated systems testing and heat-load testing, busbar runs, tap-off units, PDUs, switchgear and UPS carry a load close to design for the first time. A connection that looks fine on a lightly loaded system can show itself clearly once real current flows through it. Imaging at this stage means anything that needs attention goes back to the installer while the team is still on site, before the client takes ownership.
Load banks put out a lot of heat and halls can be warm during testing, so readings are taken at the electrical connections themselves, with the load and ambient temperature recorded, and compared against matching components on the same run under the same test.
The annual survey: what it is for
Once the halls are live, the annual survey images the critical power chain under normal operating load, with no shutdown. The site’s authorised electrician opens covers under permit to work, and every finding is recorded with its location, a thermal and a matching visual image, the measured temperature and the load at the time. As halls fill and load grows, a joint that was fine at handover can change. Comparing each year joint by joint with the commissioning baseline is how that change gets spotted early, and it builds the history insurers and auditors ask for.
Side by side
- When: commissioning happens during load testing before handover; the annual survey happens every year once the site is live.
- Load: commissioning uses test load from load banks; the annual survey uses real operating load.
- Who acts on findings: at commissioning, the installer; once live, the operator’s maintenance team or contractor.
- What it gives you: commissioning gives a clean start and a baseline for every joint; the annual survey shows what has changed since.
What commissioning thermography found on one build
During busbar load testing on a London data centre build in September and October 2026, we imaged the busbar runs section by section while they carried test load. Sixteen sections ran above 80°C. The hottest point, at a tap-off unit, measured 103.5°C. Each finding was reported with its exact location and a matching thermal and visual image, so the installer could investigate before handover rather than after the halls filled up.
Who should do each survey
Ideally the same standard both times, so the results can be compared: a certified thermographer, Level 2 or above with Level 3 oversight, independent of the installer and the maintenance contractor. Our thermographers are ITC Level 3 and Ti is a Level 3 certified company. We inspect and report; any remedial work is for the installer or your maintenance team. Reports are usually on our online portal the same or next working day, so findings can be dealt with inside a tight commissioning programme.
Related reading: when to image busbars during commissioning, annual PPM thermography, switchgear thermography, the 7 electrical risks behind data centre downtime and our data centre thermography work.
Frequently asked questions
Can the commissioning survey count as the first annual survey?
It shouldn’t. It was taken under test conditions before the halls were in use. The first survey under real operating load is the first like-for-like point, and each year after is compared with it and with the commissioning baseline.
Does either survey need a shutdown?
No. Thermography only works on equipment that is energised and carrying load, so both are done live.
What if thermography wasn’t done at commissioning?
Carry out a full survey under normal load as soon as practical after handover. That becomes your baseline from then on.
Talk to us: +44 20 3885 7464 · sales@thermalimaging.co.uk · send us your site details
About the author: Rachael Browning is General Manager of Ti Thermal Imaging, which carries out electrical thermography for data centres from commissioning to live operation, as well as FM portfolios and industrial sites across the UK and UAE. Ti’s work has featured on BBC News and ITN.