Electrical Engineering is a discipline that deals with three different areas; electricity, electronics, and electromagnetism and can involve anything from developing a powerplant to developing electronic devices within an electronics circuit. Projects within each of these fields are frequently eligible for R&D Tax Credits, where they are seeking to create a new (or appreciably improve an existing) Technology.
The UK Department for Business, Energy & Industrial Strategy (BEIS) has explicitly defined R&D Tax Credits. This briefing will help you determine the types of Electrical Engineering projects that are eligible and what costs could qualify.
The Scientific or Technological Advance must be relative to the current industry baseline within Electrical Engineering. Hence it can't be that you are applying Technology for which there is already a publicly available reference. Likewise, it can't be a commercial, business or functional Advance - it strictly must be a Scientific or Technological Advance.
For circuit design, this may be that you are developing a component for that generates 10% less heat than your existing components. It might be that a competitor's chips already release less heat than your chips, but because these are not comparable (maybe yours are faster or some other differentiator) and so achieving the reduced heat dissipation is equally claimable.
Alternatively, it may be that the project is focussing on telecommunications engineering and your engineers are attempting to create an appreciable improvement in reliability. For example, it may be that your engineers are seeking new knowledge and capability around data loss when transmitting through legacy, analogue devices.
Technological Uncertainty in Electrical Engineering
Although Electrical Engineers sometimes don't know whether some requirement will even be possible, it is more frequently the case that it is how to achieve it in practice that brings about the Uncertainty. For example, there may be several ways to reduce the heat produced by a component, however, which combination of techniques will be able to achieve this, without adversely affecting the chip's reliability, performance or physical size is uncertain.
Unlike most tradition project timelines, an R&D Tax Credits project starts when work to resolve Uncertainty commences and ends when the Uncertainty is resolved or work otherwise ceases.
Hence the initial function specification for the project would not typically qualify, but once Technological design commences, this would often be the start of working to resolve Technological Uncertainty, and so would be the start of the claim period. You can include any engineering, testing or project management. However, after overcoming the uncertainty, any support or maintenance would typically be excluded from the claim.