What does the product reference show?
Hubbell Canada's RACO 231 page describes a 4-inch square box and separately lists Depth as 2.125 in, Actual Depth as 2.425 in and Cubic Capacity as 30.3 cu.in. Those labels must stay distinct; this page does not explain away their difference by renaming one field.
The reference illustrates product identity, not a preferred box selection for a US project. Data Center Estimating is independent and is not affiliated with Hubbell or RACO. Do not infer US project approval, available stock or installed suitability from this Canadian catalog example.
Sources: Hubbell RACO: RACO 231 square box: item dimensions and cubic capacity, checked 23 October 2026
Why should gross dimensions not replace rated capacity?
Illustrative example. An estimator multiplies 4 by 4 by 2.125 and obtains 34 cubic inches. That simple rectangular-envelope calculation does not reproduce the cited product capacity of 30.3 cubic inches. It ignores the product geometry and the meaning of the published fields.
Use the actual specified item and capacity evidence for the package review. This arithmetic example is not a box-fill calculation, conductor allowance or installation design. The responsible design team determines the applicable installation requirements.
Which fields should each box line retain?
Keep covers, rings and supports visible as their own scoped items or clearly referenced inclusions, rather than assuming the box-family name includes them.
| Field | Evidence to retain |
|---|---|
| Identity | Catalog number and source revision |
| Nominal form | Square-box designation |
| Depth fields | Exact manufacturer labels and units |
| Capacity | Published cubic capacity and evidence |
| Knockouts | Required pattern and sizes |
| Accessories | Specified cover, ring and support scope |
| Quantity | Drawing reference and separately scoped accessories |
How should an ambiguous box note be closed?
Link the drawing note to the specification and item schedule. Ask the authorised technical owner to resolve unclear depth, accessory or knockout requirements before treating alternate catalog descriptions as equivalent. Preserve the clarification and any quantity changes.
This improves estimate traceability without substituting an estimator for the design authority. Engineering sign-off is performed only by the registered engineer on the job.
Common questions
What else should the bid team know?
Does 4-inch square establish depth?
No. Retain depth as a separate specified characteristic.
Can outer dimensions establish published cubic capacity?
No. Use the item-specific manufacturer capacity evidence.
Does the cited product example approve a substitution?
No. The project technical owner must review the actual requirements.