LT Panel Quotation and Specification Checklist

How to use this checklist

An incomplete enquiry is the most common reason a low-voltage (LT) panel quotation has to be revised. This checklist separates two different things: customer inputs, which are facts about the installation that only the client or their consultant can supply, and engineering decisions, which follow from those inputs and must be made by a qualified electrical engineer.

Nothing in this checklist is a design. It does not state ratings, settings or standard requirements for any particular panel, and it does not claim that any product or assembly complies with a standard. Where an item below is marked as an engineering decision, it must be confirmed against site measurements, the project single-line diagram, current manufacturer documentation and the requirements applicable to the installation.

Part 1 — Customer inputs

These items should be supplied with the enquiry. Where a value is not yet known, say so explicitly rather than leaving it blank — an unstated assumption is more expensive to correct later than an open question.

Application and load

• Application: what the panel serves — main distribution, motor control, power factor correction, generator changeover, feeder pillar, or another duty.
• Load schedule: each load with its rating, duty, starting method (where applicable) and whether it is continuous or intermittent.
• Connected load and demand load: stated separately, with the diversity assumption used to derive the demand figure.
• Future spare capacity: the spare feeder count and spare busbar capacity to be provided, if any.

Supply and system data

• System voltage and frequency and the number of phases and wires.
• Incoming supply details: source (utility transformer, generator, or both), transformer rating and impedance if known, and the earthing arrangement.
• Fault-level information: the prospective short-circuit current at the point of installation and the short-time withstand duration required. If the figure has not been calculated, state that — it must not be assumed.
• Incomer and outgoing feeder requirements: number of incomers, whether a bus coupler is required, the interlocking philosophy, and the outgoing feeder schedule.

Construction and environment

• Form of internal separation required between busbars, functional units and terminals.
• Enclosure and ingress-protection requirements: indoor or outdoor, degree of protection required, material and finish.
• Installation environment: ambient temperature, altitude, humidity, dust or corrosive atmosphere, and whether the location is air-conditioned.
• Cable entry and termination details: top or bottom entry, cable sizes and types, gland plate requirements and termination arrangement.
• Site constraints: door widths, lift dimensions, floor loading, available footprint, front-only or front-and-rear access, and shipping-section limits.

Metering, control and communication

• Metering needs: which feeders require measurement and which quantities must be recorded. See smart energy meters for the product category.
• Communication needs: protocol, physical medium, and the system the panel must report to — for example an IBMS or BMS head end.
• Indication, control and annunciation required on the panel front, and any remote control requirement.

Commercial and project requirements

• Applicable project specifications: the client, consultant or end-user specification the panel must be built to, with revision number.
• Preferred component makes, and whether alternatives are permitted. See switchgear and brands supplied.
• Testing and documentation requirements: which tests are to be witnessed, and which certificates, reports and manuals are to be issued.
• Drawings and approvals: whether general-arrangement and schematic drawings require approval before manufacture, and the approval turnaround expected.
• Installation and commissioning scope: who performs unloading, placement, interconnection, cabling, termination, testing and energisation.
• Required delivery location and schedule, including any site readiness dates the delivery depends on.

Part 2 — Engineering decisions

The following are not customer inputs. They are outcomes of calculation and design review, and they must be confirmed by a qualified electrical engineer against the project data before they are fixed in a purchase order.

• Device ratings and breaking capacity for the incomer and each outgoing feeder, derived from the calculated fault level rather than from load current alone.
• Protection and coordination requirements: the protection functions provided, the discrimination or selectivity intended between devices, and the settings that achieve it.
• Busbar sizing and support arrangement, including the short-time withstand the arrangement is designed for and the derating applied for the installation conditions.
• Thermal design: internal temperature rise, ventilation or forced cooling, and any derating required for the stated ambient conditions.
• Cable and termination compatibility with the selected devices and the available termination space.
• Which standard the assembly is verified against, which verification method applies, and what evidence will be issued. A standard being generally relevant to LT assemblies is not evidence that a particular panel meets it.

Sending the enquiry

Attach the single-line diagram, load schedule and applicable specification with the enquiry, and state which of the items above are still open. SS Exim reviews the inputs, raises the outstanding questions, and prices against the scope that both parties confirm. Related pages: custom electrical panels and the MCCB, MCB and ACB selection guide.

References

• IEC 61439-1:2020 — Low-voltage switchgear and controlgear assemblies, general rules
• IEC 60947-2:2024 — Low-voltage switchgear and controlgear: circuit-breakers

Use the editions and Indian adoptions applicable to the project. These references describe general requirements and verification methods; they do not establish that any particular SS Exim panel or component complies with them. Degrees of protection, installation requirements and statutory requirements applicable in India are covered by separate publications that should be confirmed for the project.

Engineering limitation and safety notice: This checklist is general educational guidance for preparing an enquiry. It is not a design, a specification, a quotation or an approval, and it does not establish compliance with any standard for a particular product or installation. Ratings, fault duty, protective settings, coordination and final equipment selection must be confirmed by a qualified electrical engineer against site measurements, current manufacturer documentation and the applicable statutory requirements. Work on electrical equipment must only be carried out by competent persons using the required isolation and personal protective measures.