Common electricity crisis in old houses in Shuangbei: Can the 30A main switch support modern home appliances?
Taipei and New Taipei City have a large number of walk-up apartments that are over 30 to 50 years old. When this type of old house was built, the household electricity needs were only a few fluorescent lamps, electric fans and a small refrigerator. The main switchboard installed by the builder usually only had 30A to 40A, and the diameter of the wire entering the house was often only 5.5mm² or even thinner. However, modern households also have high-power equipment such as variable-frequency air conditioners and heaters, dehumidifiers, dishwashers, microwave ovens, electric water heaters, and computers. During peak electricity consumption in summer, fire hazards such as hot distribution boxes and burnt sockets are common.
Core specifications for whole-room wiring replacement: Principle of matching wire diameter and circuit breaker
According to the latest revision of the "Consumer Electrical Equipment Installation Rules" (original house wiring installation rules) by the Ministry of Economic Affairs, the wire diameter and the amperage of the non-fuse circuit breaker (NFB) must strictly match. You must not arbitrarily increase the circuit breaker without changing the wiring:
- General lighting circuit:Use 2.0mm Single-core copper wire (current resistance approx. 19A), paired with a 15A or 20A single-pole fuseless switch.
- General wall socket circuit: It is recommended to use 2.0mm single-core wire or 3.5mm² stranded wire, with a 20A switch, and to fully configure the ground wire.
- High-load dedicated circuits for kitchens and bathrooms: Microwave ovens, dishwashers, electric water heaters, ovens, etc. must have a "dedicated circuit" drawn separately from the distribution box, using 5.5mm² stranded wire (safe current carrying capacity is about 25A), paired with a 20A or 30A circuit breaker, and an additional leakage circuit breaker.
- Instant/storage electric water heater: High-power (such as 4kW~9kW) electric water heaters need to use 8mm² or 14mm² dedicated lines and match 2P 40A~50A leakage circuit breakers.
Distribution box upgrade: the technical key to upgrading from 30A to 75A / 100A
Many homeowners mistakenly believe that they only need to buy a 75A main switch and replace it with one to complete the upgrade. This is extremely dangerous. The main switch represents the maximum current allowed to pass through the whole house. To upgrade the total amperage, three projects must be completed simultaneously:
- The house entry line after replacing the meter:The "house entry line" from the electric meter on the first floor of the building to the indoor distribution box of the home must be increased simultaneously. When upgrading to 75A, the main entrance wire needs to be replaced with at least 22mm² double-insulated copper stranded wire; if upgrading to 100A, 38mm² stranded wire needs to be used.
- Inspection of the public weak current/meter box main pipe channel: The diameter of the pre-embedded PVC threading pipes in the public stairwells of old apartments is usually small (such as 6-inch pipes or 1-inch pipes). If the original wiring in the pipe is stuck or the diameter of the pipe is not enough to accommodate three thick wires (two live wires and one neutral wire) plus a ground wire, it may be necessary to use external wall exposed pipes or re-distribute the pipes, which requires the prior consent of all residents of the apartment.
- Apply to Taipower to increase power capacity:If the contracted capacity originally applied to Taipower is insufficient, you must entrust a qualified "Type A electrician" or "water and electricity contractor" to apply to Taiwan Electric Power Company for additional electricity (application for additional amperage or replacement of large-capacity meters), pass Taipower's external line capacity review and undergo completion inspection.
Dismantling of the whole-room water and electricity renewal cost structure (taking the 25-30-square-meter old house in Shuangbei as an example)
The reasonable prices for the whole-room water and electricity renewal of old houses in Taipei and New Taipei usually include the following items:
| Engineering projects | Including content and specifications | Market reference price range (NTD) |
|---|---|---|
| Distribution box body replacement | Busbar integrated distribution box, full-room Shilin Electric/International brand NFB and ELCB reconfiguration tags | $15,000 - $25,000 / Setup |
| Re-extraction of wires in the whole room | Pacific/Wasin Lihua first-class wire rods, 2.0mm/5.5mm² dedicated circuit layout, whole room extraction of wires and pipes | $70,000 - $120,000 / Whole room |
| Exchange of electric meter on the first floor to indoor entrance line | 22mm²~38mm² thick wire extraction, stairwell pipe arrangement (price depends on floor level) | $15,000 - $35,000 / Household |
| Update of switch and socket panels | Panasonic Glatima or RISNA series grounded sockets, anti-glare switch panel | $12,000 - $22,000 / whole room |
| Update of water supply and drainage pipes in the whole room | Replacement of hot and cold water pipes with stainless steel crimped covered pipes, drainage renovation PVC thick pipe reconfiguration | $60,000 - $100,000 / Whole room |
Key points for pit avoidance and work-stealing inspection during construction
During heavy wire construction, homeowners should check three key points on site: First, confirm that there is "one wire to the end, no relay joints" in the pipe. Qualified crimp terminals or spring terminals (WAGO quick connectors) must be used for wire connection in the junction box, and black tape must not be used to wrap them casually; second, confirm that CNS is printed on the wire body. The positive mark, the year of manufacture and the brand name of the manufacturer; thirdly, after completion, use a three-purpose electric meter to measure the polarity of the socket one by one (left long neutral hole 0V, right short live wire hole 110V, round hole grounded 0V) to ensure that the live wire and neutral wire are not reversely connected, giving your family the most solid electrical safety fortress.
