Some examples I can think of where there hasn’t ever been any booked passenger workings using electric stock:
Newcastle Platforms 9-12
York Platforms 1 and 8
Doncaster Platforms 2 and 5
Historically Newcastle platforms 1 and 5-8 would have been applicable.
Newcastle platform 1:
Too short for Mark 4 sets. Now sees TPE 802s.
Newcastle platforms 5-8:
Mark 4 sets prohibited. These platforms now see TPE 802s.
Newcastle platforms 9-12:
Too short for any electric stock that serves Newcastle, including the TPE 802s. Have occasionally been used to stable 86s and 90s.
York platform 2:
Too short for Mark 4 sets. Have occasionally been used to stable 86s and 90s.
York platform 8:
Too short for Mark 4 sets, and despite being electrified only serves Harrogate line trains. I’m not aware of any record of an electric loco visiting York platform 8.
Doncaster platforms 2 and 5:
South facing bay platforms - all terminating services from the south require DMUs. Have been used to stable light 91s
Perhaps worthy of a mention is Sunderland Burdon Dock number 2 siding immediately south of Sunderland station. Though number 1 siding is unelectrified, number 2 siding is electrified for metro trains. However it is very rarely used as it requires special procedures. I’m not sure if this is still the case - historically Metro drivers were not track competent for Network Rail infrastructure. As metro units always operate in pairs and are not walkthrough, use of Burdon Dock number 2 siding required a driver in both units, both of whom had to stay with the train the entire time it was in the siding.
Also electrified on the Sunderland line is the goods loop near East Boldon - Metro units aren’t booked to use it in service (although I do recall once, many years ago, being routed through the goods loop on a Metro service, I can’t remember why that happened) and it’s use by electric trains is therefore limited.
Carlisle platforms 7 and 8 are unlikely to be used by electric trains very often, although it's plausible it might happen during certain engineering works. Similarly platforms 5 and 6, this time simply because usually they're too busy with Northern DMUs for any electric unit to get a look-in.
Though they’re seldom used by electric stock now they were regularly used by AC locos in the BR era. I seem to recall there were some moves, prior to sectorisation, where coaches detached from the front of the train at Carlisle from northbound services were shunted into platforms 7/8 by the AC loco that hauled them north, with the AC loco then returning to platform 3 to take the remainder of the train on to Glasgow.
In recent years I’ve seen a 90 in platform 8 and a 397 in platform 5, but neither are regular occurrences.