Maltepe

In the newer flats of Zümrütevler and Esenkent, electric underfloor heating mats in bathrooms and kitchens are common. A heating element nicked by a drill during renovation, or taking on damp beneath the screed, trips the residual current device specifically while the heating is on. Because the fault disappears when the heating is off, customers rarely find the cause and assume the device itself is defective.

The element is disconnected from the thermostat and its insulation resistance measured with a megohmmeter, proving the leakage truly originates in the mat. The damage point is narrowed down with a thermal camera and only that area opened for a splice; the whole floor is not broken up. The thermostat is renewed together with its floor sensor and the circuit moved behind its own 30 mA device. The repair uses a manufacturer-approved heat-shrink splice kit, because ordinary sleeving soon takes in water under screed damp and the fault returns at the same point. The cross-section of the mat supply is verified against the heating power and the measured insulation resistance written onto the service report for the customer.

In the unventilated internal bathrooms of Cevizli and Altayçeşme, shower steam leaves condensation in the ceiling junction box over the years. The terminal connection takes on damp, leakage current climbs steadily and eventually the device trips after every shower. A damp junction box looks normal to the eye; the fault can only be proven with a megohmmeter and thermal measurement.

The box is dried, terminals renewed and the connection encapsulated in dielectric silicone gel. An IP44 moisture-proof luminaire and a damp-rated extract fan are fitted, the fan wired not in parallel with the lighting but through a run-on timer so it keeps working after the shower. That dries out the root cause of the condensation.

In Küçükyalı and Fındıklı the main boards sited in the basements of seafront buildings face high humidity. Rust forms on the enclosure, green oxide on the busbar face and white salt deposits on breaker terminals. The oxidised surface raises contact resistance and starts heating, while simultaneously lowering insulation resistance and creating leakage current.

The board is locked out with a LOTO kit, busbar and terminal faces cleaned back with dielectric solvent and a protective conductive compound applied to the copper. The enclosure is upgraded to a gasketed IP54 body with an anti-condensation resistive heater and ventilation grille added inside. Every terminal is tightened with a torque wrench and a measurement report left on site.

In cheaply renovated flats in Bağlarbaşı and Girne, copper-looking cable with an aluminium core, known as CCA, has been used. Its current carrying capacity is roughly sixty percent of solid copper at the same size and it cold-creeps in terminals over time, loosening and heating. Cable labelled 2.5 mm² frequently measures closer to 1.8 mm² in reality.

To identify it, the cable end is cut and the cross-section measured with a micrometer while the conductor colour is checked at the cut face. Any branch found to be CCA is not patched but renewed from board to outlet with TSE-certified solid copper cable from makers such as HES, Öznur or Prysmian. At completion the drum label and batch number of the cable used are documented to the customer with photographs.

On night calls across Maltepe our first priority is not to repair the whole home but to get the critical loads running safely. On winter nights a dead boiler is a serious risk in households with children or elderly residents, and in summer a stopped refrigerator means lost food. After isolating the faulty leg at the board, the technician brings the boiler, refrigerator and lighting circuits back within the first ten minutes.

The boiler is afterwards always moved to a dedicated circuit with its own breaker, because a single faulty socket sharing that leg will stop the boiler at midnight in winter. Noisy chasing and breaking work for the permanent repair is scheduled for the next working day and the temporary line left safely inside fire-retardant trunking.

In the former squatter-conversion areas of Gülsuyu and Yalı, the post-meter installation has grown over the years through unqualified additions. Overhead crossings, taped splices, connections thrown into wall voids instead of junction boxes and sockets with no earth all exist side by side. Repairing a single point in such an installation does not deliver lasting safety.

First the insulation resistance of the whole installation is measured branch by branch with a megohmmeter and a condition report produced. That report prioritises which legs need urgent renewal and which can be planned. Urgent legs are renewed the same day in fire-retardant cable, a 30 mA Type A device and earth busbar added to the board, and the remainder phased to suit the customer's budget.

Apartment sub-boards receive switchgear rated at a minimum 6kA and building intakes 10kA breaking capacity. In a hard short circuit the prospective fault current reaches thousands of amperes within milliseconds; budget 3kA devices cannot quench that energy, weld their internal contacts together and rupture, throwing hot fragments outward. Breaking capacity is read from the boxed figure printed on the breaker body.

Protection stages are cascaded selectively: a 30 mA Type A life-safety device in the flat board and a 300 mA time-delayed Type S fire protection unit at the building intake. With that cascade a single socket leak trips only the affected flat instead of blacking out the whole block, while melting cable insulation is cleared by the 300 mA device before a fire starts. The cascade is built not on current threshold alone but on tripping time as well; delaying the upstream stage guarantees the downstream one opens first. After installation the trip current and trip time of both devices are measured with a dedicated tester and the values written onto the service report.

When water from the floor above fills a concealed conduit and ceiling junction box, the wall surface itself becomes conductive and touching damp masonry or a metal back-box carries a fatal shock risk. Keep clear of the board, isolate power at the building intake, then branches are isolated one by one with a digital megohmmeter, dielectric drying is applied and insulation resistance re-measured.

In wet rooms such as bathrooms and kitchens, socket and junction ingress protection is raised to IP54, and outdoors on balconies and in gardens to IP65; box interiors are encapsulated with dielectric silicone gel so moisture contact is permanently eliminated and the residual current device stops tripping. A soaked circuit is never re-energised before it dries; drying continues until insulation resistance reads at least 1 Megaohm. Where the water originates on the floor above, no electrical repair lasts until the plumbing is fixed, so the building management is notified in writing.

In a Zümrütevler flat, the whole-home residual current device began tripping the moment the bathroom underfloor heating was switched on. Arriving in twenty minutes, our technician disconnected the element from the thermostat and measured 0.3 Megaohm insulation resistance with a 500 V megohmmeter, confirming damaged cable. Briefly energising the heating under a FLIR thermal camera narrowed the abnormal hot spot to a forty centimetre area in front of the bathroom door. Only that section of screed was opened, the damaged element repaired with a manufacturer-approved heat-shrink splice kit and the floor made good. The circuit was commissioned with a new thermostat and its own 30 mA Type A device, with a final insulation reading of 220 Megaohm.

The burnt components removed during the callout were shown and handed to the customer, while the box and barcode of the original switchgear fitted in their place were attached to the service report. All work is under a 1 year guarantee.

In a Bağlarbaşı flat renovated six months earlier, the living room sockets were reported to be heating up with deformed face plates. Opening the back-box within twenty-two minutes of arrival, our crew saw grey aluminium beneath the copper colour at the conductor end, confirming CCA cable. Micrometer measurement showed the conductor labelled 2.5 mm² actually measured 1.82 mm². The terminals were loose and blackened from cold creep. The living room and kitchen branches were fully renewed from board to outlet in TSE-certified HES solid copper 3x2.5 mm² cable, all junctions closed with Wago 221 terminals, and the drum label of the cable used handed to the customer with photographs.

After the repair the whole installation was tested circuit by circuit, lighting and socket groups loaded separately for verification, and maintenance recommendations left with the customer in writing.