Hello Peter
There are two main ways the EL's get their Electrical feeder supply for both 3rd rails and signal and station lights, circuits.
The oldest 4 Manhattan (and Brooklyn) EL's (built in the 1878-1899 steam locomotive hauled train periods prior to electrification) - when electrified, built small substation buildings along side the EL's at various locations, These buildings were usually brick, stone or combinations of both, with a feeder-cables connector bridge between the building façade and the EL structure and tracks.
I modeled one of these on my O Scale NYC EL Layout - here is my EL SUBSTATION PHOTOS ALBUM with my photos of it from all angles;
https://www.flickr.com/photos/...ts/72157627892803299
THANKS BEN F for posting a photo of the street level underside view of my O-Scale modeled EL Substation and cable bridge a few messages above in this thread !!
Some of the first 1904 opened IRT Subway system EL Line extensions also had substation houses along their EL's, along with the main E.74th Street huge Manhattan Main Power House, along the East River.
In later years, cables were run underground from remote sub stations to the EL's, (and subway tunnels) and run up the EL columns where required, to the tracks and etc. Here are some Prototype photos of these EL Structure "cable columns" - including 3 images of a Power Relay Cabinet House built attached along the side of an IRT (West Farms line) EL on Westchester Avenue, Bronx, near the Intervale Ave. Station. You can clearly see the cables coming from below ground, along the columns, and up to the structure ! I have provided captions to all my photos shown below - place your cursor over the, each, photo to see the short caption.
So these photos, and my SUBSTATION photo album, give you ways to attach your feeder power cables to your model EL with realistic prototype applications !
My O-Scale NYC Model EL system also uses tube-pipes along some EL columns to run power feeder cables upward from the below my streets feeder wiring, to my EL tracks above.
BELOW are a few photos from my SUBSTATION ALBUM of my scratchbuilt IRT "Manhattan Railway Co." Power Substation modeled on the real one that powered the 3rd Ave EL I rode regularly back in my upper Manhattan old neighborhood 6 decades ago !
BELOW are some photos of the REAL 3rd Ave EL East 99th Street SUBSTATION that I based my O-Scale model on, from my photos collection. Built in 1900-01 for electrification of the 1876-77 built 3rd Ave. EL, the building still stands today ! All other Manhattan Railway Co. substations followed this same look and design.
Hope this info and all the above photos are of interest and use !
Regards - Joe F