What to Include in an RFQ for an Explosion Proof Distribution Box

“Please send price” is rarely enough to quote an Explosion Proof Distribution Box. The supplier still needs to understand what the box does, where it will be installed, what electrical load it must carry, how cables enter, and which documents the project will accept.

Start by identifying the box and its function

Use the clearest product description available: Explosion Proof Distribution Box, Explosion Proof Distribution Panel, lighting and power distribution box, replacement unit, or a new unit for a retrofit project.

If an existing unit is involved, copy the nameplate text into the RFQ and attach a photo of the complete box. Include a close-up of the protection marking, model, electrical rating and any visible certificate or standard reference.

The product name alone does not define the configuration. Two boxes with similar outside dimensions can have different circuit counts, protective devices, terminals, cable entries and internal clearances. State the function first, then describe the details that must stay the same.

Six information groups make the first quotation useful

Describe the hazardous area before comparing models

The RFQ should separate the hazardous-area requirement from the enclosure’s environmental rating. Record the information already available:

• gas or dust application;
• zone or area classification;
• gas group or dust group;
• temperature class or maximum surface-temperature requirement;
• minimum and maximum ambient temperature;
• indoor, outdoor, coastal or chemically corrosive installation;
• required ingress-protection and anti-corrosion requirements.

Do not select from IP66 alone. Ingress protection, anti-corrosion classification and explosion-protection marking answer different questions. The complete marking and the project requirement must be checked against the applicable product documents.

If the project names a local approval, certificate or inspection document, copy the wording exactly. Do not replace a named requirement with “equivalent” unless the project engineer, owner or applicable authority accepts that substitution in writing.

Give the electrical data that changes the internal layout

For a distribution unit, the main current is only one part of the design input. Include the data available for the complete assembly:

When a formal load schedule is not available, send the information from the existing nameplate, single-line diagram, breaker list or marked-up photograph. Label assumptions clearly so they can be confirmed before the drawing is approved.

Cable entries belong in the first RFQ

Cable entries affect the enclosure layout, gland selection, sealing, earthing and available internal space. “Make the same holes” is not a complete cable-entry specification.

For each entry, provide the cable type, approximate outer diameter, armour information where applicable, entry direction, thread form and required gland or sealing arrangement. If the entry positions must remain unchanged, attach a dimensioned sketch or mark the positions on a clear photograph.

• Do not mix metric, NPT and G threads by appearance.
• Use the manufacturer’s sealing range for the actual cable diameter.
• State how unused entries are treated in the project specification.
• Check cable bend radius and termination space inside the box.
• Confirm the material and environmental compatibility of glands, plugs and enclosure hardware.

For replacement work, measure the function—not only the outside

The outside dimensions are useful, but they do not describe the whole replacement requirement. A replacement unit can fit the existing opening and still fail the project if the cable entries, mounting holes, terminals or circuit arrangement do not match.

Attach these five photographs when it is safe and permitted to do so:

1. the complete installed unit and the available clearance;
2. the nameplate and protection marking;
3. the incoming and outgoing cable-entry sides;
4. the mounting face and hole positions;
5. the internal arrangement, only if opening and photographing the unit is safe and authorized.

Cover customer names, serial numbers, site addresses and other sensitive information before sending files. Circle the dimensions that must remain unchanged and label the dimensions that can be adjusted.

List the documents before the drawing is frozen

A standard datasheet and a project approval package are not always the same thing. State which documents are needed for the selected model:

• product datasheet;
• dimensional or general-arrangement drawing;
• wiring, terminal or single-line diagram;
• complete equipment marking information;
• certificate or type-test documentation for the applicable model;
• inspection or test record;
• packing and shipping information;
• customer or project specification.

The requested document must match the actual model, configuration and destination requirement. A certificate for one product family cannot be transferred to another product because the enclosure looks similar.

Use this RFQ template

Copy the block below into an email or project message. Replace unknown items with “to be confirmed”.

Product:
Model / series, if known:
Quantity:
Project country / region:
Application:
Replacement or new installation:
Area / zone classification:
Gas group / dust group:
Temperature class or surface-temperature requirement:
Ambient and environmental conditions:
Voltage / frequency / phases:
Rated current or load:
Circuit count and protection:
Cable type / conductor size / outer diameter:
Cable entries and thread / gland information:
Overall dimensions and mounting details:
Required certificate, local standard or project document:
Required delivery or project schedule:
Photos, nameplate, drawing or datasheet attached:
Open points to clarify: