VFD Specification Template for Tenders and Project Manuals

A VFD specification template is a three-part document written under MasterFormat section 26 29 23 that states the requirements every bidder on a project must meet. The template most people start from is out of date. It probably cites a drive safety standard withdrawn in February 2020.

Dmitri found that out the hard way. An electrical designer at a consulting firm in Rotterdam, he inherited a specification section from a completed water treatment project in early 2024 and reused it for a pump station upgrade. The reference list came with it. Nobody read it, including the reviewer who signed the drawings.

The tender went out with a withdrawn standard in Part 1, and one bidder wrote in to ask which revision was intended.

That question is the whole problem in one line. A specification is only as good as the references it carries, and references go stale quietly.

If you write specifications, review them, or bid against them, this guide covers the structure, the standards worth checking, and the procurement rules that decide whether you get real competition or a single bid. You’ll get a field-by-field template at the end, and every field carries the reason it is asked for.

If you are drafting a specification now and want the reference list checked against the current standards, send it to our engineers and we will mark up what needs updating.

Key Takeaways

• A VFD specification is written in three parts under MasterFormat section 26 29 23: General, Products, and Execution. Part 1 protects the owner, Part 2 defines the equipment, Part 3 governs the work.
• UL 508C was withdrawn on 1 February 2020 and replaced by UL 61800-5-1. Templates still commonly cite the withdrawn standard.
• IEEE 519-2014 was superseded by IEEE 519-2022, which changed the measurement range and added a rule for sites with on-site generation.
• Under California Public Contract Code section 3400, a brand or trade name in a public works specification is deemed to include “or equal” unless a listed exception applies.
• The clause that decides who can bid is rarely the brand name. It’s the listing and certification requirement, because it’s the one a supplier must prove.

What a VFD Specification Template Is, and Why They Fail

Four documents get confused, and the confusion causes most specification problems.

Document	Who writes it	What it does
Specification	Specifier or consulting engineer	States the requirements every bidder must meet
Data sheet	Manufacturer	Describes what one product does
Checklist	Engineer	Records what the engineer decided
RFQ	Buyer	Asks suppliers for a price

Only the first is a specification, and only the first binds anyone. A variable frequency drive specification is a contract document. If the equipment does not perform as described, the specification is what the argument is about.

A data sheet is a supplier’s claim, not a requirement. A checklist is an internal working document. An RFQ is a question.

The structure comes from MasterFormat, the numbering system published by the Construction Specifications Institute. Under it, a VFD specification section 26 29 23, Variable-Frequency Motor Controller, sits in Division 26. Related sections handle the electrical work around them.

Templates fail for a specific reason. A specification is a snapshot of one project’s decisions: its motors, its environment, its jurisdiction, its standards as they stood on the day it was issued. Copy the document without re-deriving those decisions and you inherit all of them, including the ones that no longer hold.

Two Standards Your VFD Specification Template Probably Cites Wrong

This is the reason to check a template before you reuse it. Two of the standards that appear most often in circulating VFD specifications have been replaced.

Commonly cited	Status	Current reference
UL 508C	Withdrawn 1 February 2020	UL 61800-5-1
IEEE 519-2014	Superseded	IEEE 519-2022
IEC 61800 series	Current	No change needed
NEMA MG 1	Current	Part 31 covers inverter-duty motors
NFPA 70 (NEC)	Updated on its own cycle	Check the edition your jurisdiction adopted

UL 508C, withdrawn

UL 508C covered power conversion equipment. UL 61800-5-1 replaced it, harmonizing the UL requirements with IEC 61800-5-1 and adding US national differences for NFPA 70. The transition ran in three stages, and UL withdrew UL 508C on 1 February 2020. Drives certified to the current standard are identified under UL category control numbers NMMS and NMMS2.

One nuance matters here, and it cuts against the dramatic version of this warning. UL used a continuing certification approach rather than forcing recertification. A drive certified to UL 508C before withdrawal may remain listed without investigation to UL 61800-5-1, provided its design has not changed. If it is modified in a way that requires investigation, it must then meet the full requirements of the current standard.

So citing UL 508C doesn’t buy you non-compliant hardware. It does two narrower things, and both are real. It excludes drives certified only to the standard you actually intend to require, and it leaves the specification silent about which standard applies when the question comes up. That’s a one-line fix in the reference list, and it’s worth making.

Certification for Canada follows its own CSA route, and the UL transition did not change it. Verify the current Canadian designation for your province rather than copying one from an older template.

IEEE 519-2022, superseded

IEEE 519 sets harmonic control limits at the point of common coupling, where the utility’s system meets the user’s. The 2014 revision was superseded by IEEE 519-2022, published on 5 August 2022 and retitled from “Recommended Practice and Requirements” to “Standard for Harmonic Control in Electric Power Systems.”

Two changes are worth knowing if your specification depends on it. The 2022 edition requires measurement to at least the 50th harmonic order, where earlier practice often stopped lower. It also added a decision path for sites with on-site generation: where combined site generation stays under 10 percent of annual average load demand, IEEE 519 limits apply, and above that threshold the DER standards govern instead.

A specification that cites “IEEE 519” with no year leaves the bidder to guess which limits apply. That’s one word to fix.

Harmonic limits, filter selection, and mitigation design are covered in depth in our guide to VFD power factor and harmonic specification. This section stays on the document.

The Three Parts, and What Goes in Each

Every section follows the same skeleton. The order isn’t arbitrary. Each part answers a different question for a different reader.

Part	Contents	Protects
Part 1, General	Summary, related sections, references, submittals, quality assurance, delivery and storage, warranty	The owner
Part 2, Products	Manufacturers, system description, operating requirements, features, protection	The equipment definition
Part 3, Execution	Examination, installation, identification, control wiring, adjusting, demonstration, closeout	The work

Part 1, General

Part 1 says what the document covers, what it references, and what it demands as proof. The submittals clause is the load-bearing one: it lists the documents a bidder or contractor must produce, and it’s where a specification becomes enforceable rather than aspirational.

A reference list that names withdrawn standards usually sits here, which is why this is the first place to check a reused template.

Part 2, Products

Part 2 defines the equipment. It states the required operating envelope, the features that must be present, and the protections that must operate. This is where the performance-versus-proprietary decision is made, and section 4 covers how to make it without closing the bid.

The operating requirements are the technical heart of the document. Input voltage and tolerance, frequency, output range, overload capability and duration, efficiency, ambient and altitude limits, enclosure type, and cooling all belong here.

Part 3, Execution

Part 3 governs the work: examination of conditions before installation, installation requirements, identification and labeling, control wiring, field adjustment, demonstration and training of the owner’s staff, and closeout documentation.

This part is where a specification earns its keep on a retrofit, because it defines what happens when the installed conditions do not match the drawings. A specification with a strong Part 2 and no Part 3 leaves that dispute to the field.

Write It Performance-Based, Not Brand-Locked

There are three ways to specify equipment, and they aren’t equal.

Performance specification states the required outcome and leaves the means open. “Output current not less than 15 A continuous at 40 degrees Celsius ambient, with 150 percent overload for 60 seconds.”

Proprietary specification names a manufacturer, brand, or model. Most restrictive, and the one that limits competition.

Prescriptive specification describes the means in detail without naming a brand. Middle ground, and easy to over-specify.

For public projects, performance-based wording is the preferred approach in a wide body of procurement rules. Virginia’s construction and professional services manual requires that a non-proprietary performance specification be written so that at least three manufacturers can meet every requirement. Arkansas building authority rules name performance and non-proprietary formats as preferred.

Utah’s rules require specifications not to require a proprietary supply or sole source unless no other description will meet the need. Check your own jurisdiction, because the details differ and the preference isn’t universal.

The “or equal” statute

California’s rule is the sharpest example. Public Contract Code section 3400 applies to public works specifications. It bars specifications that limit bidding to one concern, or that call for a designated product by brand or trade name, unless the words follow the specification “or equal.”

The section does more than state a preference. It requires a time period, before or after award, for a bidder to submit data substantiating that a proposed substitute is equal. If no period is stated, data may be submitted within 35 days after the award. If the specifying agency knows of an equal product manufactured in California, it must name it.

Section 3400(c) lists the exceptions, and they matter because they are legitimate. For example, a brand may be named without “or equal” for a field test or experiment, to match products already in use on the project, when the item is available from only one source, or in a declared emergency. Matching existing equipment is a real engineering reason, and it’s used correctly every day.

However, the exception is narrow. It covers the equipment being matched, not a habit.

What a closed specification costs

The mechanism is worth understanding, because a specification can look open and be closed.

In C. Lawrence Construction Company, Inc., B-290709 (September 2002), the GAO sustained a bid protest over an interior signage specification. The document named one manufacturer and also allowed “pre-approved manufacturer with an equal product.” But a separate clause stated that where a specification names a single product, no substitutions would be permitted, and no other manufacturer had been pre-approved by the time bids closed. The GAO found the solicitation reasonably open to the reading that only the named product would be accepted, and noted there was no evidence in the record that only that manufacturer could meet the agency’s needs.

The lesson transfers directly to drive specifications. An “or equal” clause with no approval mechanism and no stated deadline is not open. It’s closed with extra words.

In contrast, Noor ran into the other side of this. An owner’s representative for a food processing plant in Malaysia, she specified a single premium drive brand for a 2022 line expansion because the plant already ran that brand and spare parts were on site. That was a matching decision, and it was defensible.

Two years later she applied the same approach to a new packaging hall with no installed base to match, and the tender drew one bid. Reissued on a performance basis with the duty point fixed, it drew five.

The duty point is what makes a specification openable. Name the current, the voltage, the load type, and the overload class, and a qualified supplier can build to it. Name a part number and you have described one company’s catalogue.

Writing a substitution clause that works

The bid protest above failed for a mechanical reason, and the fix is mechanical too. A workable substitution clause has four parts: a statement that equivalents will be considered, a named point of contact, a deadline expressed in days before bid opening or after award, and a list of what a substitution request must include.

The deadline is the part most often left out. Without one, a bidder cannot tell whether there is time to submit. The receiving agency can therefore decline any request as late.

California sets a statutory default window of 35 days after award. A specification should state its own window rather than rely on the fallback.

The Real Gate: Listing, Certification and Submittals

Here is the part most specifications get backwards. The clause that decides who can bid is usually not the brand name. It’s the listing requirement.

A specification that requires every drive to be listed and labeled by a nationally recognized testing laboratory is asking for a document, not a design. A supplier either holds that listing or doesn’t. No amount of engineering argument substitutes for the certificate.

UL 61800-5-1 appears in exactly one of the 129 articles on this site, and CSA C22.2 appears in none. The certification side of drives is the thinnest coverage in the whole library, and it is the side that governs whether a drive may be installed at all.

A specification should require, as a minimum, the listing itself, the certificate file or evidence of listing, and the manufacturer’s declaration that it covers the specific model. Ask for them as submittals, and mark which ones must be approved before equipment is ordered rather than after.

What the listing clause actually requires

Listing is not the same thing as compliance with a standard. A listing is a third-party determination that a specific product from a specific manufacturer meets a defined set of requirements, recorded against that manufacturer’s file.

That distinction matters when the equipment supplied is a drive built into a custom assembly rather than a factory package. The individual components can each be listed while the completed assembly still needs its own evaluation. A specification that requires a listed drive but says nothing about the enclosure leaves that gap for someone to find during inspection.

The submittal register

The US government’s Unified Facilities Guide Specification for adjustable speed drive systems under 600 volts, UFGS 26 29 23, is a useful model because it groups submittals by type and marks which need approval before work proceeds. The categories transfer to any jurisdiction:

Category	Typical contents
Shop drawings	Schematic and interconnection diagrams, installation drawings, as-built drawings
Product data	The equipment schedule, cross-referenced to the drawings, with quantities and motor compatibility
Test reports	Factory and site test results, performance verification, endurance runs
Certificates	Testing agency credentials, and the listing evidence
Manufacturer’s instructions	Installation literature
Manufacturer’s field reports	The test plan, and reports from site visits
Operation and maintenance data	The maintenance package for handover

Mark each line as either approval required or informational. A register where everything needs approval stalls the project. A register where nothing does leaves the owner unprotected.

One drafting note. Some of these categories exist to satisfy a specific owner’s process rather than a technical need. Copy the structure, not the entire list, unless your project genuinely requires each item. A bloated submittal register gets ignored, and an ignored register protects nobody.

The VFD Specification Template: Every Field to Fill In

This is the deliverable. Work through it in order. Every field carries the reason it is asked for, because a field with no reason gets filled in wrongly or left blank.

Duty point

Field	Why it is asked
Motor rated power, kW	Cross-check only. Current, not power, sets the drive rating
Motor full-load current, A	The sizing baseline at rated load
Motor rated voltage and phase	Determines the drive’s input and output configuration
Motor rated frequency, Hz	The base point for the V/f relationship
Load type	Constant torque, variable torque, or constant power. Sets the overload requirement
Overload class and duration	Typically expressed as a percentage of full-load current for a stated time. A project decision, not a fixed value
Duty cycle	Continuous, intermittent, or cyclic. Drives cooling and derating
Number of starts per hour	Steady-state thermal loading on the drive and motor

For how to derive these from a nameplate and a load profile, see our VFD sizing guide for motors.

Installation and environment

Field	Why it is asked
Maximum ambient temperature	Above 40 degrees Celsius most drives derate. Sets the output current available
Altitude	Above 1,000 metres, cooling and insulation clearances change
Enclosure or IP rating	Set by the installed location, washdown, dust, and wet conditions
Cooling method	Air or water. Affects heat rejection and plant services
Motor cable length	Long runs need an output reactor or dv/dt filter
Supply arrangement	Transformer size, available fault current, and whether a line reactor is required

Control, options and interfaces

Field	Why it is asked
Control mode	V/f, sensorless vector, or closed-loop vector. Follows from the load type and the speed accuracy needed
Speed range and regulation	Defines the operating window and the accuracy the process needs
Feedback requirement	Encoder or sensorless. Determines whether closed-loop control is available
Fieldbus protocol	Must match the plant’s control system, not the drive’s preference
Required I/O	Digital and analogue points, and relay outputs for the plant’s signals
Braking method	Resistor or regenerative. Determined by how much braking energy the duty cycle produces
Filters and reactors	EMC level, line reactor, output reactor, or dv/dt filter as the installation requires
Certificates and marks	The listing, plus any regional marks the project requires

Commercial and delivery

Field	Why it is asked
Quantity	With spares stated separately
Delivery location and Incoterm	Determines who carries freight and duty
Warranty term and basis	State the term and what starts the clock
Required documentation set	The submittal package, stated by category

Do not leave the overload class blank. Rafiq, an applications engineer at a drive supplier, received a tender for a conveyor package in 2025 with no overload figure anywhere in the document. He asked one question to clarify it, and the specifier realised the template had omitted the requirement entirely. Three bidders had already priced the job on three different assumptions.

That’s what an incomplete field list produces: bids that cannot be compared, and a low bid that is low because it assumed less.

Frequently Asked Questions

What is a VFD specification template?

It’s a reusable three-part document, written under MasterFormat section 26 29 23, that states the requirements every bidder on a project must meet for variable frequency drives. Part 1 covers general requirements and submittals, Part 2 defines the equipment, and Part 3 governs the installation and closeout.

Is there a standard VFD specification?

No single universal one exists. MasterFormat gives the section number and the three-part structure, and the US government publishes UFGS 26 29 23 as a master specification for drives under 600 volts. Beyond that, content is set by the project, the jurisdiction, and the owner. Any template you find is somebody else’s set of decisions.

Should a VFD specification name a manufacturer?

Generally not, unless you have a specific reason to. Performance-based wording keeps competition open and is the preferred approach under many procurement rules. Where a brand is named, many jurisdictions either require it to be followed by “or equal” or read those words in by statute, and a substitution process with a stated deadline should be included.

Which standards should a VFD specification reference?

At minimum the drive safety standard, currently UL 61800-5-1 for the United States, the applicable electrical code edition, and the harmonic limits standard at its current revision, IEEE 519-2022. Add the motor standard for the duty, and any regional certification the project requires. Always cite a revision year.

What are VFD submittal requirements?

They are the documents a bidder or contractor must produce as proof of compliance, grouped by type: shop drawings, product data and equipment schedules, test reports, certificates including the listing evidence, manufacturer’s instructions, field reports, and operation and maintenance data. Mark those that require approval before work proceeds.

Conclusion

Four things decide whether a VFD specification template works.

The standards in it are current, with revision years stated. The wording is performance-based, so more than one qualified supplier can bid. Every field in the duty point is filled in, so bids can be compared. The submittal register is defined, so compliance can be proved rather than asserted.

Check a reused template in the order this article does it: the reference list first, because it goes stale silently and nobody reads it. Then the Part 2 wording, because that’s where competition is won or lost. Then the field list, because that’s where bids become comparable. The VFD selection guide covers the engineering behind the duty point, and the terminology guide explains which word to use when a specification is formally reviewed.

The standards will change again. UL 61800-5-1 has already been through one generation, and IEEE 519 has an active revision project in progress. A specification is a dated document, and treating the date as part of its content is the difference between a template and a liability.

If you would rather have the reference list and the field list checked before the tender goes out, our engineers do that as part of selection support. Send us the draft, along with the duty points, and we will tell you what is missing.