Site Generator Setup: Prime vs Standby, Silent Units, Fuel and Connection

A request for a site generator in Egypt usually arrives as a single number: "a 100 kVA generator for a month." Sometimes that is exactly right. Often it is a guess that turns into a set that trips every time the tower crane lifts, or one twice the size it needs to be, burning fuel at a fraction of its load. And the number says nothing about the things that decide whether the rental works: how close the neighbours are, who refuels it, how far the cable runs, and who connects it.

This guide covers setting up a site generator for construction sites, factories and buildings that need temporary or standby power: how to arrive at the size, the rating to ask for, when a silent unit is worth it, and the fuel and electrical arrangements to settle before the set arrives.

Size from the loads, not from the last site

The full sizing method is in what size generator a construction site needs. In short:

1. List every load: site offices and their air conditioning, lighting, welding sets, pumps, concrete vibrators, hoists, a tower crane, small batching or workshop equipment.
2. Separate running power from starting power. Motors on cranes, pumps and compressors draw several times their running current as they start. The generator has to carry the biggest start on top of what is already running.
3. Convert honestly from kW to kVA using the power factor the generator is rated at, and do not assume every load runs at once, but do not assume they never do.
4. Allow for heat. Output falls at high air temperatures, and an Egyptian summer afternoon is exactly when the site offices' air conditioning is at full load.

The result is usually a class, not a precise number, and a good lessor will check it against the list. Sending the load list with the enquiry is the single most useful thing you can do.

Why bigger is not automatically safer

It is tempting to order a size up "to be safe". Up to a point that is sensible: a margin covers motor starts and the heat of an Egyptian summer. Beyond that, oversizing costs twice. The rate is higher, and a diesel set that runs for weeks at a small share of its rating does not burn its fuel cleanly: deposits build up in the engine and exhaust, and the set needs more service. Most manufacturers advise against long running at very light load. If your load is small at night and large in the day, two sets, or one set sized for the day with a small set for the night, is usually better than one large set running half-empty around the clock.

Prime or standby: ask for the right rating

Generators carry two ratings, and the difference matters for a rental.

• Prime power is what the set can deliver for long hours as the main supply, with normal variation in load. A site with no grid connection runs on prime power.
• Standby power is a higher figure intended for emergencies, for limited hours, when the grid fails. It is not meant for a site running on the generator all day.

When a quote says "100 kVA", ask which rating that is. A site that will run on the generator every day should be sized on the prime rating.

Typical set-ups on Egyptian sites

Two smaller sets instead of one large one is often the better answer on a site whose load swings between day and night: one runs at night, both run in the day, and a breakdown does not black out the whole site.

Silent units near homes and in new cities

Most new-city projects in Egypt are built next to homes that are already occupied, and a generator running through the night is the fastest way to a complaint. Silent (canopy) generators enclose the set in a sound-insulated cabinet and are the standard choice near housing, hospitals, schools and hotels. Ask the lessor for the unit's rated noise level, and place it well:

• As far from homes and offices as the cable run allows.
• Exhaust pointing away from windows and walkways.
• Not in a closed space, where heat and exhaust build up.
• On firm, level ground, with room around it for service access.

In gated compounds, check the developer's rules on where a generator may stand and when it may run before you book the delivery; many developers set them, and a breach can stop the site. A canopy also protects the set from sand and dust, which on desert and coastal sites is an advantage in its own right.

Fuel: autonomy, refuelling and records

Ask how many hours the set runs on a full tank at your expected load, then decide who refuels and how often. On a site running around the clock, refuelling is a daily logistics job, and a set that runs dry at night stops the site the next morning. Agree:

• Who supplies fuel, and how it is measured: tank readings at handover, delivery notes, and a daily log.
• Where the fuel is stored, in a proper container away from ignition sources, and how spills are contained.
• Security. Fuel on an unattended site is a target; a lockable tank cap and a record of readings discourage losses.

What drives fuel consumption, and why a record beats any rule of thumb, is covered in how much fuel heavy machines burn; the same logic applies to generators.

Cables, earthing and the connection

The generator is only part of the installation. Settle these before delivery:

• Cable length and size from the set to the main distribution board, and who supplies the cable. A long run needs a larger cable, or the voltage at the far end drops.
• Distribution board and protection, including earth-leakage protection for site circuits.
• Earthing of the set and the installation, done properly.
• ATS if the set is standby for grid power, so the changeover is automatic and the two supplies can never be connected together.
• A qualified electrician to make and test the connection. That is not the generator lessor's job unless the contract says it is.

Service and breakdowns on a long hire

A generator on a monthly hire needs routine service at the intervals the manufacturer sets: oil, filters, and checks on coolant and belts. Agree who does it, how it is scheduled so the site is not left without power, and what happens if the set fails: how fast a technician arrives, and whether a replacement set is provided. For essential loads, ask about a standby set on site.

How generator rental is priced

Rates are usually quoted by the day, week or month, and they move with:

1. The size class in kVA.
2. Duration, with lower effective daily rates on longer terms.
3. Running hours: some contracts assume a set number of hours a day; continuous running may be priced differently.
4. Fuel: included or supplied by you.
5. A technician on site or on call.
6. Cables, distribution board and ATS, if the lessor supplies them.
7. Transport and unloading: larger sets need a crane or a truck with a crane to place them.

If the set will run around the clock, say so plainly in the enquiry. It changes the service schedule, the fuel plan and the rate, and a quote built on a day-shift assumption will not hold for a site that never switches off.

What to send in your request

1. The load list, or the main loads with their ratings.
2. Prime or standby use, and hours a day.
3. Duration and start date.
4. Location, and how close the nearest homes or offices are.
5. Fuel arrangement.
6. Cable distance from the set to the main board.
7. Whether you need an ATS, and which loads are essential.
8. Access for delivery: can a truck reach the set's position.

Next step

EXON rents generators from its own machines, delivered to sites across Egypt, and the list rates are published: the generator rental page lists the sizes available. If you have the load list ready, send it to the EXON team on WhatsApp and ask for a project quote.