A quote for a commercial generator system is only as good as the enquiry behind it. The generator switchgear and the changeover device are only two lines on the same sheet. A duty nobody described cannot be priced at all.
Key Takeaways
- The enquiry sets the price. Generator rating, fault level and load tiers decide more of the total than the panel size does.
- Names hide scope. A gen switch and an industrial ATS share a job but never a bill of materials.
- Ask for priced lines. A lump sum cannot be compared with another lump sum.
- Commercial duty is not domestic duty. A whole building restarts its largest motor, not one circuit.
- Documents travel with the panel. A test record and a load schedule are part of what you paid for.
What a supplier needs before an ATS quote means anything
Every comparable quote starts from the same set of inputs. Send them once and every supplier prices the same scope.
The generator rating comes first, in kVA and in step load. A set that stalls on pickup cannot be rescued by a larger panel.
The fault level at the incoming terminals comes next. It sets the breaking capacity of every device in the generator switchgear. The same figure sets the short circuit rating of the busbar.
The load schedule carries the most weight of all. It names the essential ways, the non essential ways, and the order the panel must shed them in.
Site conditions decide the enclosure. A coastal plant and an air conditioned switch room are two different products at the same rating.
Standby capacity keeps growing across Africa and South Asia. The IEA tracks that shift each year in its annual outlook work.
Ask what else the supplier needs before they price. Most will name one or two items you have not prepared.
The front of the panel is the smallest line in the quote
Indicators, a controller and two latched handles are what a visitor sees.
The priced scope sits behind them, in the busbar, the devices and the test.
Device names that decide the scope of a commercial enquiry
Buyers write six different names into the same tender line. Each one carries a different scope, a different bill of materials and a different price.
A gen switch is one changeover device in one box. A gen transfer switch adds an enclosure and a single outgoing way.
A 220 volt manual transfer switch is the cheapest way to move a small load. It also needs an operator standing beside it when the mains fails.
An electrical transfer box holds the same device in a sealed enclosure. It suits one circuit, not a building.
An industrial ats is an assembly with a busbar, protection and a controller. That is the scope a commercial generator system usually needs.
The same tender may also ask for generator switchgear. That term describes the assemblies around the set, not one device.
Ask for the six names to be defined in the enquiry itself. A supplier who accepts your words without asking is guessing at the rest of the scope too.
The priced lines that make two bids comparable
A lump sum hides every decision that matters. Ask each supplier to price the same lines separately, then compare like with like.
Six lines carry most of the difference on a commercial changeover panel. Everything else follows from them.
| Priced line | What it covers | Where bids diverge |
|---|---|---|
| Enclosure | Steel, paint, door hardware, ingress class | Indoor sheet steel against a sealed outdoor build |
| Transfer device | Changeover device, rating and type | A manual switch against a controller driven device |
| Protection | Incoming and outgoing devices, settings | Whether the settings are tested or left at default |
| Busbar | Material, section, plating and fault rating | Copper against a thinner bar at a lower rating |
| Control | Controller, wiring, terminals and signals | Whether the controller is wired and tested in the works |
| Test and dispatch | Routine test, record, packing, freight terms | Ex works against delivered and unloaded |
Ask for the single line diagram beside the price. It shows whether a generator disconnect sits before or after the changeover.
The wording of the scope matters as much as the total. A tender that asks for a switchboard vs panelboard comparison is really asking which assembly carries the changeover.
Two suppliers can hold the same devices and still quote a different scope. The shorter bid is not cheaper, it is smaller.
Sizing the changeover to a building rather than a circuit
A commercial building does not fail like a house. When the mains drops, every chiller, lift and pump tries to restart at once.
Size from the load that must survive, not from the connected load. A 1,250 kVA plant may only need 700 kVA kept alive.
Three numbers set the rating of the changeover. The starting current of the largest motor, the step load the set accepts, and the time the shedding takes.
A standby set accepts load in about 12 seconds at a steady ambient. A transfer switch for backup generator duty has to carry that first surge without opening.
Upstream of the changeover sits the main switch distribution board. Its rating and its fault level both flow into the panel you are pricing.
The assembly around it is often described as a low voltage switchgear panel. The scope of that term still varies by supplier.
Sizing starts with a figure the panel can trust
Current transformers and terminal blocks carry the load signal to the controller. Without them the shedding order is a timer, not a decision.
Ask for the ratio and the accuracy class with the quote. Both change the price more than the device rating does.
What has to arrive with the panel
A panel is not finished when it leaves the works. Four documents should travel with it, and a quote that omits them is cheaper for a reason.
- The routine test record. Which tests ran, the results, and the serial number they belong to.
- The single line diagram. The drawing that matches the panel as built, not as designed.
- The load schedule. Every way, its tier and its place in the shedding sequence.
- The setting list. Device settings, current transformer ratios and the controller parameters as left.
A panel built to IEC 61439 carries a routine test record for the assembly. The load schedule is what turns that assembly into a managed one.
Work with a supplier running an ISO 9001 system. Those records are then ordinary production paperwork.
Ask for them in the enquiry rather than at the end of the project. A supplier who knows the records are wanted builds them into the job.
What a certificate actually tells you
Where the same rating still comes back at two prices
Two quotes for the same duty can differ by a third. The gap is rarely the rating, and almost never the copper alone.
A sealed outdoor build costs more than a sheet steel enclosure indoors. A tested controller costs more than an untested one.
The assembly that carries the changeover sets its own floor price. A electrical switchgear assembly with spare ways costs more than a sealed box with none.
Freight and unloading sit at the end of almost every gap. Ask for the terms in writing before you rank the bids.
Sending the enquiry so the bids line up
One covering note removes most of the guesswork. Send the generator data, the load schedule, the fault level and the site conditions together.
Add the date you need the panel on site. Delivery drives device choice more often than price does.
Name the person who can answer technical questions. A supplier who cannot reach an engineer prices the worst case.
Frequently asked questions
Can I get a quote without a single line diagram?
Is an electrical transfer box the same as an ATS panel?
What are the types of transfer switches for generators?
Does a commercial generator system need a generator disconnect?
Why does an outdoor transfer switch for generator duty cost more?
What does generator paralleling switchgear add to a quote?
Can one supplier quote the panel and the generator together?
How long should a quote stay valid?
Final thoughts
Yes, quotes are easy to get. Comparable quotes are harder, because they depend on what you send and what you insist on seeing.
Send the generator data and the load schedule. Ask for priced lines. Check the documents against the price.
Send your generator rating, your load schedule and your site conditions. Giantele engineers will return a marked panel layout and a technical proposal for the assembly.
Comparing changeover panel bids for a generator backed building?
Send the generator rating, the load schedule and the site conditions. Giantele engineers return a marked layout and a technical proposal. It covers the changeover device, the protection and the handover evidence.
