What HV/LV Switching covers
"Switching" in Singapore's electrical industry is the controlled operation of an electrical installation — energising, de-energising, isolating, earthing — performed under permit, by an authorised person, with the right credentials for the voltage involved. Get it wrong and you risk fatalities, fires and expensive equipment write-offs. Get it right and the installation never knows you were there.
AK Engineering provides two distinct but linked services here: (1) hands-on switching by an EMA Licensed Electrical Worker (LEW) for installations up to 1 kV, and (2) High Tension (HT) system design and implementation at 22 kV and 66 kV, where the PE Electrical role takes over.
LEW switching services (up to 1 kV)
Under the Electricity Act, certain switching, energising and isolating operations on electrical installations may only be performed by a Licensed Electrical Worker. Er. James holds a lifetime EMA LEW licence (No. 9/21492) authorising operation of equipment up to 1 000 volts.
- First-energisation of new LV installations.
- Isolation and Permit-to-Work (PTW) issuance for safe working on de-energised equipment.
- Switching schedules — written, signed, executed and recorded.
- Lockout/Tagout regimes for major outages.
- Re-energisation procedures following maintenance, fault repair or modification.
- LEW Hand-Over Certificate for TOP submissions where the LEW is taking on the installation.
HT system design & implementation (22 kV / 66 kV)
The Professional Engineer side of the practice covers everything above 1 kV — system design, equipment selection, protection co-ordination, room/building integration, energisation strategy and T&C oversight. Er. James led 66/22/LV utility services at Changi Airport, designed 22 kV substations for LTA infrastructure works, and has endorsed 22 kV S/S installations for industrial clients including Macdermid and EMK Technologies.
Typical HT scope
- Load demand analysis and intake sizing.
- Single-line diagram development.
- Switchgear specification — RMU, vacuum CB, SF6 switchgear.
- Transformer selection — dry-type vs oil-filled, rating, vector group, impedance.
- Protection co-ordination study — relay settings, time-current curves, selectivity.
- Cable sizing and routing — between intake, transformer and LV switchboard.
- Earthing system design — system, equipment, lightning earths.
- Substation room — civil/architectural co-ordination, ventilation, fire compartmentation.
- SP PowerGrid intake submissions and liaison.
- HT switching plans for first energisation.
Process — typical HT intake project
- Demand & intake. Calculate the connected and diversified load, decide whether HT intake is required, prepare SP intake application.
- Concept design. Single-line, substation footprint, transformer ratings.
- Detailed design. Equipment specs, protection co-ordination, cable schedules, earthing.
- SP approval cycle. Submissions, RFI responses, conditional approval.
- Procurement & installation oversight. FAT witness, site installation supervision.
- Testing & commissioning. See our T&C service.
- Energisation & handover. HT switching by SP; LV-side switching by the LEW; LEW Hand-Over to client.
Standards we work to
- SS 638 — Code of Practice for Electrical Installations (LV).
- IEC 61936 — Power installations exceeding 1 kV AC (HV).
- IEC 62271 — High-voltage switchgear and controlgear.
- SS 551 — Earthing.
- SP PowerGrid Service Connection Document.
- EMA Electricity (Electrical Installations) Regulations.
Frequently asked questions
Do you switch on HT directly?
HT switching at SP-owned 22 kV is performed by SP authorised personnel. On the customer side of the intake, HT switching requires a Class 2 or Class 3 LEW. Our practice is licensed for 1 kV LV; for HT switching we work with HT-licensed colleagues. We always design with that hand-off in mind.
Can you produce a switching schedule for our outage?
Yes — switching schedules with isolation points, earthing positions, permit boundaries and a step-by-step sequence are part of the LEW deliverable for any planned outage.
What's the lead time on a 22 kV intake?
From SP application to energisation is typically six to twelve months depending on cable route, equipment lead times and SP's load capacity in the area. We give you a realistic critical-path plan up-front.