Factory power supply in Malaysia: converting amps to kVA, TNB supply classes, upgrade costs and timelines, and a due-diligence checklist for buyers and tenants

Before you sign for any factory in Malaysia, find out how much power it can actually draw, and whether that covers your machines with room to spare. A listing that says "300 Amps" gives you just over 200 kVA of three-phase capacity. That is plenty for a packing warehouse and nowhere near enough for a line of injection moulding machines. Upgrading later can mean months of waiting for TNB, connection charges, a new switchboard and sometimes land for a substation. Check power supply first, and judge the price after that.

Of everything I check before a shortlist, power is the item buyers and tenants most often get wrong. Here is how to read the numbers and what to ask.

What the amp rating on a listing actually means

Most Malaysian factory listings quote power in amps, such as "200A" or "400A". That is usually the rating of the main incoming supply or breaker, not what your machines need.

Three-phase supply in Malaysia runs at 400/230V, so you can convert amps to capacity like this:

kVA = 1.732 × 400V × amps ÷ 1,000

Machine nameplates usually show kW, not kVA. To get usable kW, multiply kVA by your power factor. Many industrial sites run at around 0.85.

Quick conversion table (three-phase, 400V, 0.85 power factor)

These are rough figures for planning only. Your electrical consultant will work out the actual load.

How TNB classifies supply by size

TNB sets the supply type according to your maximum demand (MD), which is the most power you draw at any one time. Under TNB's published supply classifications:

• Single-phase LV: up to 12 kVA. This is for small shops and offices, not factories.

• Three-phase LV, direct-metered: up to 72 kVA (100A). This is common in older terrace and cluster factories.

• Three-phase LV, CT-metered: up to 1,000 kVA. Most semi-detached and detached factories in Klang Valley fall here.

• Medium voltage (11kV): 1,000 to 5,000 kVA. At this level you need your own substation, and usually a consumer switch room and transformer.

• 33kV and above: 5,000 kVA and up. This is for heavy manufacturing and large campuses.

The step that catches people out is going from direct-metered (100A and below) to CT-metered, or from LV to 11kV. Each step brings a new meter arrangement, new equipment and, often, a longer wait.

Worked example: will a 200A factory run your line?

Say you run a small plastics operation and want to move into a semi-D factory in Shah Alam that is advertised at 200A.

Your connected load

The calculation

Not everything runs at full load at the same time. If your consultant applies a diversity factor of about 0.7, your maximum demand is about 152 kW. At a 0.85 power factor that is about 179 kVA, or roughly 258A at 400V.

The 200A supply gives about 118 kW, which is short by more than 30 kW. A 300A supply would cover you with only about 25 kW to spare, so it is tight if you plan to add a fourth machine. A 400A supply is the comfortable choice.

Your options: keep looking, negotiate the upgrade into the deal, or budget for it yourself.

What a power upgrade involves

If the building doesn't have enough supply, you, or the owner, will need to apply to TNB for additional load. The broad steps are:

1. Appoint a registered electrical consultant to calculate the load and prepare drawings.

2. Submit the supply application to TNB through your consultant or a licensed electrical contractor.

3. Pay the connection charge and the deposit TNB asks for.

4. Upgrade the switchboard, cabling and metering. For CT-metered supply, this includes CT metering.

5. Provide substation land or a substation room if TNB requires it.

6. Have the installation tested and connected.

Connection charges for low-voltage CT-metered supply

TNB's published connection charges for CT-metered three-phase LV supply are banded by maximum demand. Some of the bands:

For additional load, TNB charges the difference between the new and existing load charge, so moving from the 91–120 kW band to 181–240 kW costs about RM5,400. That is only TNB's charge. Consultant fees, a new main switchboard, cabling and trenching usually cost far more, so get a contractor's quote first.

The substation trap

Under TNB's connection charge terms, for loads above 60 kW the consumer may have to provide land for a substation where TNB requires one. That land is transferred to TNB for a nominal RM10. On a fully built-up intermediate or semi-D lot, there may be nowhere to put one, and that can stop an upgrade completely. Check whether the estate already has a substation with spare capacity before you count on an upgrade.

How long it takes

TNB's guidance to investors has quoted 6–12 months for 11kV connections, and longer for higher voltages. Lead times depend on the site and local network capacity, which is a live issue in Selangor: in September 2026 the state said new data centres are approved only after TNB confirms grid capacity. If your move date is fixed, don't leave an upgrade as a loose end.

Your power due-diligence checklist

Ask for these before you make an offer or sign a letter of offer for a tenancy:

• ☐ The latest TNB bill, which shows the tariff category, recorded maximum demand and account status

• ☐ The main switchboard rating and incoming cable size, confirmed on site and not just copied from the listing

• ☐ Whether the supply is direct-metered or CT-metered, and the CT ratio if it is CT-metered

• ☐ The location of the nearest substation, and whether it serves only this lot or is shared

• ☐ Any outstanding TNB arrears or disconnection history on the account

• ☐ Whether there is a generator set, and what it is rated for

• ☐ Who is responsible for the installation and its upkeep under the tenancy, including any competent-person arrangement

• ☐ The current power factor, since a low reading points to correction equipment you may need to add

Pitfalls I see again and again

• Treating the listing figure as fact. "400A" sometimes describes the building as designed, not the supply that is actually approved and metered. Check it against the bill and the switchboard.

• Ignoring your peak. On medium-voltage accounts, TNB bills charges per kW of maximum demand, and your MD is set by your single highest 30-minute period in the month. Starting several big motors at once can push up that month's bill.

• Forgetting the exit cost. If you upgrade a rented factory, read the reinstatement clause. Some landlords will want the upgrade left in place for free, while others will want it removed.

Rules and thresholds change, so confirm with the relevant authority or a lawyer before committing. For electrical design, rely on a registered electrical consultant, not on a listing or an article.

Finding a factory with the right power

Many of the factories that suit power-hungry operations never reach the portals. I match clients directly to suitable stock, including off-market units and upcoming completions, and I check the power supply before anything goes on your shortlist. You deal with me directly, with no call centre and no junior negotiator.

Start with current factories for sale or factories for rent, or browse by area: Shah Alam, Klang, Nilai, Sepang and Puchong. If you are weighing up whether to own or lease, read buying vs renting a factory in Klang Valley.

WhatsApp me your requirements: your area, built-up size, budget, and your machine list or the kW you need. I'll tell you what is realistically available. More common questions are answered in the FAQ.

FAQ

How many amps does a factory need in Malaysia?

It depends entirely on your machines. Add up the kW on the nameplates, apply a realistic diversity factor, and convert the result to amps. Light assembly or storage may run on 100–200A. Moulding, metalwork or cold rooms often need 300A or more.

Is 100A three-phase the same as 100 kVA?

No. At 400V, 100A three-phase is about 69 kVA. TNB's limit for direct-metered three-phase supply is 72 kVA (100A).

Can I upgrade the power supply of a rented factory?

Usually yes, if the landlord consents in writing and TNB approves the additional load. Agree before you sign who pays, who owns the upgrade, and what happens at reinstatement.

When do I need my own substation?

Loads above 1,000 kVA move to 11kV supply and need a substation. TNB may also require substation land for loads above 60 kW when the local network can't take the load.