The wedge

The VFD enclosure catch — a real $5K story

A mechanical estimator uploads a bid set. Plans, schedule, and spec all disagree on the same VFD's enclosure rating. Bid the wrong number and the change order eats the margin. Scoprix catches it in 30 seconds.

Step 1 — Three sources, one VFD

Plans, equipment schedule, and spec book all reference VFD-1. They don't agree.

Plans (sheet E-2.1)
VFD-1

Keyed note 4 — All VFDs in mechanical yard shall be in NEMA 4X enclosures suitable for outdoor coastal wash-down (1-mile from shoreline). Min salt-spray rating: 5,000 hr per ASTM B117.

Equipment Schedule
VFD-1

VFD-1 / 25 HP / 460V / 3φ — Enclosure type: STANDARD. Mounting: outdoor pad. No enclosure rating note.

Spec § 26 29 13
VFDs

PART 2.04 — Variable Frequency Drive enclosure shall comply with NEMA 250 Type 4. Salt-spray exposure per ASTM B117 — 1,000 hr minimum.

Step 2 — Scoprix detected 2 discrepancies

Enclosure rating contradiction across sources

HIGH

Plans call out NEMA 4X (wash-down, coastal). Schedule lists STANDARD. Spec calls NEMA 250 Type 4 (not 4X). Three different ratings on the same VFD — bid will land on the wrong scope.

Estimated impact: $3,200 – $5,400

Salt-spray rating mismatch

HIGH

Plans require 5,000-hr salt-spray ASTM B117. Spec says 1,000-hr minimum. 5,000-hr-rated equipment is a 4–8 week lead-time premium item — order on the wrong assumption and you ship late.

Estimated impact: Schedule risk + $1,800 – $3,000 hardware delta

Step 3 — RFI ready to submit

Scoprix drafts the RFI with verbatim citations from each source — no re-typing, no chasing references.

RFI #007 — VFD-1 Enclosure & Salt-Spray Rating

Per Sheet E-2.1, Keyed Note 4: VFDs in the mechanical yard are called out
as NEMA 4X with 5,000-hour ASTM B117 salt-spray rating, suitable for
coastal wash-down. However:

  • Equipment Schedule (Sheet M-7.3) lists VFD-1 enclosure as "STANDARD"
    with no rating note.
  • Specification § 26 29 13, PART 2.04, requires NEMA 250 Type 4 (not 4X)
    with 1,000-hour ASTM B117 minimum.

Please confirm:
  1. The enclosure rating that governs (NEMA 4X per plans, or Type 4 per
     spec). 4X is recommended given the coastal proximity called out in
     the keyed note.
  2. The salt-spray hour rating that governs (5,000 hr or 1,000 hr).
     5,000-hr-rated equipment is a long-lead specialty item and may
     impact the project schedule.

If the 5,000-hour / NEMA 4X requirement governs, recommend reissuing the
equipment schedule with the updated rating to align all three sources.

Submitted by: [your name]
Sheet references: E-2.1, M-7.3, Spec § 26 29 13
Export: CSV · PDF · CSI-pagedStatus workflow: open → acked → submittedAddendum diff — re-run after RFI response

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