The Saudi Electricity Company supplies most commercial and industrial loads at medium voltage. But where does SEC's responsibility end and yours begin? Who owns the transformer? Who pays for the protection? The MV interface decisions made at design lock in 25 years of operating cost.
Four ideas to carry into the next specification conversation you have.
Up to the supply transformer secondary: SEC. From there: customer. Some sites (large industrial) own the transformer too, pays for itself in tariff savings.
kWh = energy consumed. kVA = peak demand (15-min average). kVARh = reactive penalty if pF below threshold.
100 kVA, 500 kVA, 1 MVA, 10 MVA, each threshold has different unit prices and demand structure. Pre-design the contract demand carefully.
Peak afternoon (1-5 PM, Saudi summer) is most expensive. Mid-night base loads can be 60% the daytime rate. EV charging and data centre cooling are big TOU optimisers.
SEC standard MV distribution voltages.
| Voltage | Typical use | Ownership / interface |
|---|---|---|
| 400 V LV | Small commercial, residential | SEC up to meter |
| 13.8 kV MV | Standard commercial / light industry | SEC to transformer secondary |
| 33 kV MV | Large industrial, district cooling | SEC to dedicated substation |
| 132 kV HV (sub-trans) | Mega-projects (NEOM, Aramco, big malls) | Dedicated step-down at customer |
| 380 kV HV (transmission) | Major industrial cities, IPP | Direct interconnection agreement |
Five decisions that shape 25 years of operating cost.
SEC-owned: simpler, lower upfront cost, you pay LV tariff. Customer-owned: higher upfront, you pay MV tariff (lower per kWh), you maintain the transformer. Crossover typically at ~500 kVA continuous load.
The kVA you declare to SEC sets your monthly fixed charge. Declare too high = paying for unused capacity. Declare too low = penalty surcharge if you exceed. Audit historical demand before declaring.
kVARh meter records reactive energy. Industrial tariffs charge for it above the pF threshold. APFC bank payback typically 12-24 months on any commercial site with motor loads.
Saudi summer afternoon peak (13:00-17:00) is the most expensive hour. Pre-cooling thermal mass, scheduling EV charging at 22:00-06:00, and running data-centre cooling at off-peak can cut electricity costs 15-30%.
Saudi grid code mandates specific protection relays, metering classes (Class 0.5S), and disconnect arrangements at the MV interface. Use SEC-approved nameplates only. Non-compliance delays energisation by months.
We design customer-owned and SEC-owned MV substations, manage SEC interconnection paperwork, install Class 0.5S metering, and tune contract demand against historical load profiles.
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