Planning a TNB Shutdown: Temporary Power and Lighting Are Two Separate Jobs
A planned supply interruption is one of the few jobs where contractors genuinely need a standalone genset — and also need site lighting. They are two different hires from two different suppliers, and confusing them is what causes the 2 a.m. phone call.
A Shutdown Has Two Lighting-and-Power Problems
They get treated as one, and they are not
A scheduled supply interruption — for a substation upgrade, a cable diversion, a switchgear replacement or a planned maintenance window — creates two separate requirements at the same time.
- Keep the load running. The building, the plant, the cold rooms, the lifts, the servers. This needs a generator sized to a connected load.
- Light the work. The crews doing the actual job, usually outdoors, usually at night, in an area where the supply is off by definition.
They are solved by different equipment from different suppliers, and a plan that only covers the first one runs into the second at about 9 p.m. ⚡
Job One — Temporary Power for the Load
This is a genset requirement, properly sized
Sizing a generator for a shutdown starts from connected load in kVA, accounts for motor starting currents, and considers whether the changeover is manual or automatic.
What that hire involves
- A load schedule and a properly calculated kVA rating
- Changeover arrangements and who operates them
- Cabling, distribution and protection
- A competent person to make the connections
- Fuel management for the full duration
None of this is guesswork territory. Use a generator supplier who does shutdown work, and give them the load schedule early.
Job Two — Lighting the Work
The area with no supply is the area being worked on
By definition, the part of the site under a shutdown has no power. That is exactly where the crew is working, and it is where any lighting you plug in has nothing to plug into.
A mobile light tower solves this because it is a silent diesel generator carrying an 8 m telescopic lighting mast. It makes its own power and produces light directly, so it does not care that the supply is off.
Why not just run lights off the temporary genset?
You can, and sometimes it is right. But it means adding lighting load to a generator sized for something else, running leads out to the work area, and having a lighting failure become a power problem. Keeping the two separate is usually simpler and always more robust.
What TerangPro Does and Does Not Rent
Stated plainly, because this article is about a job where the distinction matters most:
- We rent light towers. MCWEL MLT8S — 8 m telescopic mast, four 500 W lamps, silent diesel generator on board, trailer-mounted, RM 3,500 per unit per month including delivery and set-up.
- We do not rent standalone generator sets. The generator is part of the light tower. There is no generator-only rate and no separate genset in our fleet.
If you need temporary power for a load during a TNB shutdown, we are not your supplier for that part and we will say so immediately. If you need the work area lit while it happens, that is exactly what we do.
Planning the Lighting Side
Identify the work areas, not the affected area
The supply interruption may cover a whole block. The lighting requirement covers only where crews are actually working — the substation compound, the excavation, the cable route, the access road.
Work out the count
For a compound or an open works area, plan around 3,000 to 3,500 m² per tower, round up, and add a unit if the work cannot pause. Our coverage guide has the full method.
Do not forget the public interface
A shutdown often affects a street, a car park or a building entrance that the public still uses. Lighting a dark public area during an outage is a real safety measure, not an extra.
Watch the glare
Substation compounds are often next to roads and housing. Raise masts fully and aim downward and inward — the same discipline as any road-adjacent job. Our night work lighting guide covers the hazards to check.
A Working Timeline
- At planning — split the requirement into power and lighting, and give each to the right supplier.
- Four weeks out — confirm the lighting count against the actual work areas, not the outage area.
- One week out — confirm access and where the units can physically stand.
- The day before — units delivered, positioned and stood up while it is still light.
- Before the shift — masts fully raised, aiming checked, dark seams walked and closed.
Step 4 is the one most often compressed, and it is the one that causes problems. Nobody wants to be positioning a trailer in the dark on the night the supply goes off.
Get the Lighting Sorted
Send the work areas, the outage window and the site location. We confirm availability and quote a fixed monthly rate per tower — nationwide, including Kuala Lumpur, Ipoh and George Town.
Frequently Asked Questions
Can I rent a generator from TerangPro for a TNB shutdown?
No. We rent light towers only. For temporary power to keep a load running, use a generator supplier who does shutdown work.
Can a light tower power anything else?
It is built to run its own lamps. Treat it as a lighting unit, not as a power source for tools or equipment.
How many towers for a substation compound?
Plan around 3,000 to 3,500 m² per tower depending on how obstructed the compound is, round up, and add one if the work cannot pause. Send us the layout and we will suggest a count.
Can units be delivered the day before the outage?
Yes, and that is what we recommend. Positioning and standing units up in daylight is far safer and faster than doing it after the supply is off.
Is the rate different for a short outage window?
We price per unit per month. Message us with the window and we will tell you the most sensible arrangement.
The Short Version
A planned supply interruption creates two jobs: keeping the load running, and lighting the work. The first needs a properly sized generator from a generator supplier. The second needs a self-powered light tower, because the area being worked on has no supply by definition.
We do the second. We will tell you plainly that we do not do the first. 🔦