戶外走線加設防水線槽，申請獨立電錶，7kW 單相。難處：電錶位於屋內，車位在屋外，需穿牆敷設 8 米外露走線。Outdoor conduit run, dedicated meter applied, 7kW single phase. The problem: meter indoors, bay outdoors, an 8m exposed run through the wall.
A village house in Tai Po Tsai, Sai Kung, with a ground-level bay at the front, partly under a canopy. The meter and distribution board are inside the house near the stairs; the bay is outside, with a structural external wall between them.
The owner commutes into town daily, around 2,000 km a month — firmly in the higher-consumption group.
The hard part
Getting through the wall, in the right place.
Meter inside, charger outside, so the wall has to be penetrated. Simple in principle, but in practice:
The penetration mustn't compromise the structure (you don't drill a load-bearing wall casually)
It has to suit both the board inside and the bay outside, or you lengthen the run on both sides
It has to be waterproof, or rain tracks along the cable and into the house
The indoor section has to look tidy, because it's right by the stairs and visible every day
And with the owner's high consumption, the metering choice needed rethinking too.
What we did
Chose the penetration point. After measuring on site, we went through the wall low down and directly behind the distribution board. That kept the indoor run to about 1m, fully concealed in trunking beneath the board — barely visible from the stairs.
Waterproofed the penetration. A sleeve through the drilled hole, set higher outside than inside, so any water running along the cable drains outward rather than seeping in. Both ends sealed with weatherproof compound.
The 8m outdoor run. From the penetration along the exterior wall to the bay in UV-resistant trunking with sealed joints, deliberately routed tight into the wall corner to keep it visually quiet.
Applied for a dedicated meter. At 2,000 km a month and around 350 kWh of charging, he's in the higher-usage group. We costed it: the dedicated meter's upfront expense amortises within a reasonable period through the tariff difference, and the billing is transparent and his own. So we recommended a dedicated meter and handled the CLP application.
Protective devices. A new dedicated circuit with a Type A 30mA RCD, with 6mA DC leakage detection built into the charger. On completion we issued the electrical test record listing insulation resistance, earth resistance and RCD trip times.
The outcome
About five weeks from meter application to completion, most of it waiting on CLP. The site work itself took half a day.
The owner reports the dedicated meter's billing is clear — he can see the monthly charging cost at a glance and doesn't have to reconcile figures with anyone.
Who this case is useful for
Meter inside, bay outside is an extremely common village house layout. Three things worth knowing:
A good penetration point can halve the cable run. Get someone on site to choose it before ordering; don't settle it over the phone.
The sleeve must sit higher outside than inside. It's the easiest detail to skip and the most annoying to live with when rain finds its way in.
If your consumption is high, cost out a dedicated meter properly. Above 300 kWh a month it usually beats a shared arrangement long-term.
Want to know where your wall should be penetrated and which metering suits you? WhatsApp us photos of the meter and the bay and we'll give you an opinion first.
你的物業與這個案例相似？Does your place look like this one?
傳送車位及電錶相片，我們會告知最接近哪一種情況、需時多久及費用多少。Send photos of your bay and meter. We'll tell you which case yours resembles, how long, and how much.
