N Scale Catenary

First let us make the key assumption that you've decided to model both masts and wires like me.  Given that there is no need for any visible difference between operational and non-operational catenary then it makes sense to keep it non-operational (not just to avoid being electrocuted every time you touch your model - cleaning catenary to ensure smooth operation in N scale would be torture!)  

Though I'm sure Sommerfeldt and Viessmann make wonderful catenary, it's very expensive to fit it across a large non-club layout.  Hobbex makes a cheaper version but it's harder to get hold of in the UK and in my irrelevant opinion looks a bit too plastic-like.  Making it yourself is more fun than just buying it and will give real satisfaction upon completion to a standard that one can bare to look at in a dimly lit room!

Design

Gantry catenary is much easier to make and much more sturdy than the single line stuff, and has the additional benefit that it can span any number of tracks with simple modification of the design.  Not ideal for non-mainline usage but then I'm much more interested in twelve coach EC/IC trains roaring along through pristine alpine scenery that single coach railcars annoying motorists at level crossings!

My initial design is shown below, conforming to the NEM standards issued by the ludicrously named MOROP, a link to whose website I refuse to provide on the grounds of taste.  I've made it as simple as possible without loosing the 'feel' of the stuff so that when it breaks it's easy to fix!  (Admittedly the catenary shape is no longer true.)  For more tracks the design can be stretched and a more realistic catenary shape used.  All dimensions in mm unless otherwise marked:

The H columns will probably be brass rods which are widely available in suitable thinness (2.0-3.0 mm at base).  Insulators will be made from wiring code-cylinders or resistors and diodes painted grey (ironic given that it won't be functional to use electronic components!)  Piano or garrotte wire will be used for the actual wires with the cross wires thicker than the contact wire in order to strengthen the gantry. 

I'll probably use unrealistically thick contact wire (1mm) because very thin wire (0.5 mm) has to be kept very tight or the locomotive pantograph will cause an even less realistic deflection!  (There's nothing I despise more...)  Some people prefer to reduce the spring strength of their locomotive's pantograph but I fear that fiddling with pantographs is liable to make then deploy skywards spontaneously and perhaps get ripped off at the next tunnel entrance on layouts without catenary.

Construction

Will commence when the layout is started or sooner if I have time.