
STEP 6
Last Time Buys & Stockpiling
Publishing Date: 08-Oct-2025
Read Time: In-depth guide | <20 minutes
Reviewer: Christoph Horlebein, CEO Horlebein Consulting
LTBs can prevent redesigns and ensure continuity—but they come with hidden costs. This step explores how to calculate LTB quantities, weigh redesign vs. stockpiling, and apply models like Porter Refresh and MOCA. Learn how to store, monitor, and preserve LTB inventory to avoid degradation, waste, and compliance risks.

Author: John Wombwell (MD, CNX Technology and Innovation Group)
Theme
Standard & Clause
LTB / Life of Need Buy Definition & Use
IEC 62402 §10.3 • SD-22 §4.4
Notification Handling (PCN, PDN, NRND)
IEC 62402 §9.2 • SD-22 §3.3
LTB Quantity Calculation & Service
Obligations
IEC 62402 §10.3 • SD-22 §4.4
Cost Analysis (NPV, Porter Model)
IEC 62402 §11.2 • SD-22 §4.4
Stockpiling & Storage Requirements
IEC 62402 §10.3; Annex C • SD-22 §4.4
Compliance Monitoring During Storage
IEC 62402 §4.1; §8.10 • SD-22 §4.3
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About the author

John Wombwell
John Wombwell, founder of CNX Technology and Innovation Group, has over 25 years of experience in Component Engineering and Obsolescence Management. A Royal Air Force veteran, his career spans work with radar, missile, and communication systems across defense, medical, and rail industries worldwide. Now focused on advancing proactive obsolescence management, John shares his expertise through CNX as initiator of the 12 Steps framework and the International Institute of Obsolescence Management.
