An offshore wind farm isn't run by one contractor. The turbines are usually maintained under a full-service or warranty agreement with the OEM, running for the first five to ten years or longer. The balance of plant — array cables, substations, foundations — sits under a separate contract, often with the asset owner's own operations team or another specialist. Marine coordination, crew transfer vessels and SOV scheduling can be a third arrangement again. Three contracts, three workforces, one site.
Each of those contractors typically runs its own version of control of work, if it runs one at all. That's fine until people from different contracts need to work on or near the same asset at the same time — which, on any array doing scheduled major component exchange alongside cable repair alongside routine turbine service, happens constantly.
What control of work actually needs to cover on a wind farm
Control of work is the set of processes — permits, isolations, authorisations — that governs who can access equipment, under what conditions, and what else must be true before that access is granted. On an offshore wind asset it needs to answer one more question that a single-operator oil and gas platform doesn't usually have to ask: which contract does this piece of work sit under, and does the person authorising it actually have visibility of what the other contracts are doing on the same turbine or array that day.
The OEM agreement doesn't see the rest of the site
A turbine service technician working under the OEM's contract has authority and competency defined against that agreement. They don't necessarily have any system-level visibility of a balance-of-plant crew accessing the same tower base for a cable termination, or a marine coordinator routing a CTV to the same turbine for a different job. If each party's control of work sits in its own system — or in paper permits held locally by each contractor — there's no shared picture of what's live on that asset at that moment.
This is the same underlying problem we've written about in the context of why permit to work needs SIMOPS visibility on oil and gas assets: simultaneous operations only stay manageable if everyone working the site can see what everyone else is doing. On a wind farm, the added complication is that the people who need that shared view work for different companies, under different contracts, with different reporting lines back to the asset owner.
Isolations that cross contractual boundaries
Electrical isolation is where this tends to surface first. A high-voltage isolation on a turbine or array cable might need to remain in place to protect a balance-of-plant crew, while the OEM's technicians are simultaneously working inside the nacelle under their own permit referencing the same isolation point. If the isolation register lives inside one contractor's system and the permit lives inside another's, someone has to manually reconcile the two — and reconcile them correctly, every shift, for the duration of the work. We've covered the general failure mode of isolations sitting outside the permit system in isolation management: the SIMOPS blind spot; in a multi-contractor wind O&M setting it's not a blind spot within one operator's process, it's a gap between two organisations' processes that neither party owns outright.
Shift handover carries the same risk in a different form. A CTV-based technician working a day trip handing over an unfinished job to a colleague arriving on the next crossing needs the same clarity that offshore oil and gas teams rely on for permit continuity across a shift boundary — something we've set out in more detail in shift handover protocols that keep SIMOPS safe. Add a second or third contracting party into that handover and the coordination burden doesn't add up in a straight line, it compounds.
When permit records become commercial records
OEM service agreements are typically structured around turbine availability, with payments or liquidated damages tied to how much of the contracted period the turbines were generating. When a turbine is offline longer than expected, the first question the commercial teams ask is rarely about safety — it's about who had access, when, and under whose authorisation, because that determines which party's contract governs the downtime and who bears the cost.
A control of work record that shows exactly who held a permit on that turbine, when it was accepted, when it was suspended or extended, and when the isolation was removed, is the evidence base for that conversation. Where the record sits inside one contractor's siloed system rather than a shared or interoperable platform, reconstructing that timeline after the fact means requesting records from multiple parties and hoping the timestamps line up. Where it's held in a single system that all parties write to, the sequence of events is already there.
This is worth separating clearly from the safety case for control of work. The safety justification for a shared system doesn't disappear, but the commercial one is distinct and, in a contract with liquidated damages clauses, arguably just as consequential. It's why some asset owners are beginning to specify data standards or minimum control of work capabilities directly in O&M tender documents — not just as a safety requirement of the contractor, but as a condition of how disputes over availability and liability will eventually be resolved.
What to specify before the contract is signed
If you're drafting or reviewing O&M tender documents, a few practical questions are worth asking before commercial terms are finalised rather than after an incident forces the issue: can the proposed control of work system show a permit issued by one contractor against an isolation owned by another? Can it produce a complete timeline of access to a specific turbine across all contracts operating on that asset, not just the one issuing the request? And if the OEM, the balance-of-plant contractor and the marine coordinator each run separate systems, is there an agreed mechanism — shared platform, integration, or at minimum a common data export standard — for reconciling them, or is that left to be worked out operationally once the contract is live?
These aren't abstract governance questions. They determine whether a dispute over a missed availability target six months into an O&M contract gets resolved with a clear audit trail or with three companies comparing incompatible spreadsheets. We've written more broadly about what connects a control of work system end to end in digital control of work: connecting the system, and the same principle applies across contractual boundaries as much as it does within a single operator's asset.
If you're involved in structuring or reviewing an offshore wind O&M contract and want to talk through how control of work requirements are typically specified between an OEM agreement and balance-of-plant scope, we're happy to walk through what that's looked like on other arrays.