Ian McAulay

It depends who you ask... I've seen L4M, L4(M), L4m and L4(m) from different sources. For what it's worth, the Blaw Knox drawings for them say L4(M), but that may be the whim of the draughtsman, and all the other lettering on the drawing is in capitals too. Also, the drawing is referring to a CEGB specification and I have no idea how that was bracketed or capitalised. On the other hand, CEGB drawings for L6M (punctuate according to taste) are labelled L 6 M - no brackets, all caps and spaces between characters. Their drawings for L7C don't have spaces or brackets. I don't think there ever was a pre-metric L4. The numbering of tower series seems to have been fairly random, certainly not sequential and with gaps. I go for 'series' for L2, L3, L6 and so on. The appropriate field on the National Grid tower database is LINE_SERIE (presumably there's a field limit of 10 characters somewhere). Blaw Knox drawings say 'specification' on L2 and L4M drawings, which is probably strictly correct. CEGB for L6M, L7C and L12 have 'tower series'. Just to be different, LSTC use 'tower design' on their drawings for the proposed (and I think abandoned) L4S and L7H series. Given that CEGB used 'series', I think that's authoritative. 'Tower type' seems to be universal for D, D30, D60 and so on. I think that may actually have clarified things a little. Answers to questions like that usually just make the subject murkier. Ian

Pylon King: I'm really enjoying your 1/76 pylon models. I've just reread the article in May BRM but my favourite has to be the SF60 with maintenance cradles. Sadly, neither of the micro-layouts I'm working on really have space for a pylon. Maybe I'll just have to build one anyway! Ian

Not an area I know at all, so can't comment. However, some of those 132kV lines are likely to be part of the original National Grid. It would be instructive to have a look at old mapping to work out the earlier layout. The National Library of Scotland is a great resource for this. The One-inch New Popular Edition is probably most useful. It was published 1945-47, so guaranteed not to have any 275kV on it. It may not exactly reflect the electricity network at that time as updates took longer to filter through to published maps than they do now, and of course we'd just had a war. Link: https://maps.nls.uk/os/one-inch-new-popular/ I find the seamless layer they offer if you follow that link to be the most useful as you don't need to know sheet numbers. Ian

The climbing aids are called "step bolts" (reasonably enough). They are usually (but not always) on two diagonally opposite corners of the tower, and on both faces of the steel angle that forms the corner, and staggered so they work like a minimal ladder. They usually (but again, not always) start just above the anti-climbing barbed wire to discourage illicit adventurers. Ian

I did a bit more investigating on L2's Are Great's posting of the odd tower photo above. The tower is at OS grid reference SD 96098 10973, just west of Denshaw village and just south of where the line crosses the A640. Tower number ZPA042. It's listed on the National Grid network database as L2 D60 but it's pretty clear that it has short crossarms both sides. (Also, being a D60, the earthwire isn't central on the tower peak. The line is perfectly straight at this point, so my guess is that it's because of the steep slope to the south; a suspension tower would suffer from uplift on the insulator strings. This is what D10's were invented for, but maybe something tougher was needed? And why L2 on an otherwise L8 line? I would imagine that you could do the same thing with an L8 D60 as the starting point, but I haven't a clue. Interesting find though. Ian

Hi Folks I've been a lurking member of RMWeb for years, but wasn't aware of this thread until Daniel alerted me to it. (I've been in email correspondence with him over the last few weeks.) I'm an architect by training, but have actually worked in computer visualisation and mapping for environmental assessment for most of my career (now ended since retirement in 2016). A recurring theme has been power line projects, some quite big. I was active on the PAS board some years ago with the handle Dr Fortran, but haven't been involved in anything online about pylons for a long time. I'm still catching up with the discussions, but I'll chip in if I see anything where I can contribute. Ian