Cliff Street substation

This Sunday morning I was off to a New York Transit Museum tour of the Cliff Street substation and surrounding neighborhood. This wasn’t my first substation tour, but my fourth! Someday I’ll catch up and write about all of them.

Somehow I thought it wouldn’t be that hot outside, maybe because thunderstorms were in the forecast, but boy was I wrong. It was humid and sticky already on my combination drive-and-train trip down to the financial district. Despite the heat I walked swiftly from the nearest subway stop to the location my smartphone mapped out for me, just down the street from South Street Seaport on a now-pedestrian-only plaza. I quickly checked in with museum workers then tried to find a shady spot as I waited for the tour to begin.

I stepped back and looked up at the substation building. It made sense that this place was billed as a sister to the Greenwich substation – their imposing brick façades with tiny art deco details were cut from the same cloth.

The other tour participants kept occupied by reading the packets we were handed, readying cameras, drinking bottled water, and trying to keep cool.

In front of the substation

Waiting for the tour to start

Reading the literature

A few minutes early we were ushered in through the tall, open doorway. I recognized our tour guide for the day from the previous substation tours. He fired up the amplification machine and began to speak over the fairly loud constant hum of the equipment (another commonality between the substations).

Sign above door

View from substation door

He gave a quick overview of the early history of mass transit in New York, from electrification of the elevated trains to the opening of the first subway in 1904, to planning the IND subway system in the 1920s. A theme through his story was that riders always wanted more – trains were always overcrowded and demands for service to new areas soared.

Power infrastructure had to keep up with the building of these new lines and systems. The first two subway companies, the IRT and BRT (later BMT) built their own power stations to power their trains. Along the routes, substations converted their power from high voltage AC (alternating current) to 625 volts DC (direct current). The IND system followed a similar plan of substations, of which this (#7, Cliff Street) was one, but purchased commercial power rather than producing its own.

I tried to take good, accurate notes as our guide spoke, but he always presents way too much information for me to capture all of it. Even after being on several tours, I feel by no means proficient in electrical principles or the finer points of subway history. I suppose it’s a process! While listening I also gazed up at the tallness of the interior of the building. A huge crane hung above us, presumably for moving heavy equipment in and out of the substation.



Behind me at the gate a couple of people had assembled. Before, when we were waiting, I’d overheard a few passers-by ask the museum folks what we were doing. I guessed these people were asking the same, and I silently hoped that they would get interested in this secret infrastructural world around them and/or get involved with the Transit Museum.

Talking to curious people

During the introductory speech our tour guide also passed around a few big color photos from the substation’s past. One showed damage to a now-replaced piece of equipment after a flashover in 2002.

Photo of damage to an old rotary converter

We walked under some complicated-looking equipment towards the back of the building. A zigzag of stairs rose up to our left. Our guide stopped us here in between a blocks of gray machines which stood much taller than us.

Equipment above

Staircase up

Our tour guide

He began to explain the modernization of this substation, which followed the path of most of the others, though timing of each varied slightly. In the beginning, the power was converted with huge rotary converter machines. Though now decommissioned everywhere, I’d seen a couple of these old machines in the other substations, and the photo he’d passed just before we walked showed one too. They resemble giant metal donuts, maybe eight or ten feet in diameter, mounted upright with part hanging through to the floor below. They’re quite impressive to look at due to their scale. Metal brushes inside the spinning ring worked to convert the alternating current to direct current.

In the modernization of the substations, these great beasts were replaced by solid state rectifiers. The gray cabinets that house these rectifiers are stoic, sterile, and unmoving in contrast to the rotaries. The rectifiers resemble banks of 1960’s room-filling computers but with fewer flashing lights.

Other components were replaced in the modernization too, he said. In the middle of the floor sat a waist-high, complicated-looking box: a modern, high-tolerance circuit breaker.

Solid state rectifiers

Solid state rectifiers and circuit breaker

New circuit breaker

At the back wall was still more evidence of the substation’s past and present. Guide pointed out a big black box diagramming the nearby subway lines’ power layout, with buttons at various intervals. This, he said, was how power used to be monitored and controlled. It only indicated whether the power was on or off. To the left of that was a smaller black box with a touchscreen map of the same area. This modern piece of equipment could tell much more information about the power flow, which is helpful for troubleshooting purposes.

Old control panel

New touchscreen control panel

As we rounded the corner to head back to the front of the building on the other side, our guide answered questions about “that radiator looking thing,” which I think he said was part of a transformer.


I looked up at the giant crane again, noticing it said “Cleveland Crane” on it. Could this machine have been made in my hometown?

Crane bridge

Our guide talked a little bit about cooling in the substation, which was key when the rotary converters were in service. We passed a fan control panel and he explained that hot air would have been blown from the basement up a wide duct at the back of the building and out its top.

Fan control

Ventilation duct

We circled back to return to the area of the overhead equipment and, with a device resembling a broom handle in his hand, guide explained safety precautions. No matter what the modern (or old) gauges and indicators read, one final check would be done to make sure the power was off in an area before doing work there. He reached up with the stick and an arc of sparks connected it with the bare part of the equipment above. You could practically hear the crowd “oooh” at the demonstration. However thrilling, it also seemed quite logical to take such a precaution!

Next we headed to the basement. Most opted to take the small spiral staircase (either for fun or because they were following the group), though there was also a wider, straight staircase available.

Spiral staircase down

Near the bottom of the stairs our guide picked up some objects off a cluttered table. These, he said, were “hockey puck” diodes. I held one and felt its weight.

Supply table

“Hockey puck” diode

We listened as guide talked about the substations also generating air power, which used to work the subway’s signaling systems and stop arms. He also told a story which was familiar to me about how the MTA made a 40-year deal with ConEd that the latter would provide the former with 25 Hz power to run the subways. When this contract was set to expire in 1999 and the MTA hadn’t modernized all of its infrastructure, it scrambled to purchase frequency converters rather than pay exorbitant fees to ConEd. Our guide tells this story with flair and suspense, and indeed it sounds like it was a close call.

Tour participants listen

We walked towards the back of the building in the basement. This first room was filled with giant cables reaching from floor to ceiling, some sort of tank (maybe a fire extinguisher?) mounted on a cart so that it looked like a cannon, and some wiring equipment that was perhaps in the process of being dismantled.

Cabling in basement

Not sure what this is

Taped off equipment

We went around the corner and entered a room parallel to the one we were just in. Our tour guide called this the “negative room” and told us this is where the power returned to the substation once it completed a circuit. The power, he said, will return through whatever route it can, and has been known to eat away at bridges and sewer mains. I’d never heard this before and it sounded fascinatingly destructive. Our guide pointed out the return cables, which are apparently insulated with oil.

In the negative chamber

Working our way back towards the front of the building and the staircases, we entered another room. This space, guide said, used to help provide commercial power to the surrounding area – part of the historically cooperative relationship between the power companies and the subway systems.

In this room, big batteries were stacked on one side. Guide told us that these served as a backup for the control system (since this substation is controlled remotely from the power control center) and the communications systems in the case of a power failure. In this vein, he touched on his story of the 2003 blackout, another one I’d heard before but always enjoyed. Working as a superintendant then, he’d just finished a meeting with some electric company executives when everything went dark!

Backup batteries

It was time to go back upstairs and take a quick break before the walking tour portion of the day. Feeling heat exhausted, I was one of the first up the stairs.

Our guide points out a detail

I tried to relax and cool off during this break, going from inside to outside the building (though that didn’t help much). From the sweaty shirts, disheveled faces, and water bottles in hands, I knew others were feeling the heat too. Some asked our guide side questions as we waited.

Before we left, guide walked us over to a table we passed by at the beginning of the tour. On it were lightbulbs and stacks of paper. Guide passed out these second paper packets, information related to the walking tour, and told us that these old, carbon filament lightbulbs were used as indicator lights to synchronize the frequency of the rotary converters with the frequency of the electricity coming from the power station.

Old indicator lightbulbs

Guide also gave us a primer on Thomas Edison and the beginnings of the electrification of New York. Edison bought up two buildings on Pearl Street and constructed a powerhouse, which he used to light up a section of the financial district starting in 1882. This powerhouse used direct current, and went from supplying 59 customers to 500 in just a year. Though this was quite a triumph, it took seven years for Edison to make back the large investment he put into the endeavor.

With this introduction, we were escorted outside and we watched as guide closed up the substation building.

The substation

Art deco pattern on door

Closing the doors

We first walked east on Fulton Street (towards the Seaport). In about a block guide stopped us in an atrium-like building entrance. Here, he pointed out a plaque dedicated to Edison and his Pearl Street powerhouse.

Edison plaque

On the next corner we looked over barricades at some utility work being done in the street. Though I couldn’t hear our guide very well (we were spread out and there was street noise) I assume at least some of this work was electrical in nature.

Utility work

As we gathered closer, guide told us about a project he was involved in where the steel-encased subway cables were dug up to replace them with cables in a better casing material. In the digging process, guide and the other workers found some of Edison’s original feeder cables. Lengths were donated to various museums, and guide kept one short section which he had brought it to show to us. The metal wires were insulated with rope, pitch and beeswax, and a crumbling cast iron casing surrounded the whole thing. Because of its age, this object would have been almost unrecognizable without the explanation. But it was fascinating to see and touch such a piece of history!

Our guide holds a piece of Edison cable

Next we walked down Pearl Street. We stood across the street from a medium-sized, empty-ish parking lot dwarfed by tall buildings. Here, our guide said, stood Edison’s power station. The station was only in use from 1882 to about 1895, and suffered a severe fire during that time, necessitating replacement of much of the original equipment. Guide also told us a story or two about Edison’s less upstanding side – he had a history of “borrowing” and building on the work of other inventors (including Nikola Tesla), when it resulted in profits for him.

Where Edison’s power house was

Our next stop was the Excelsior Power Company Building, just north on Gold Street, a narrow little alleyway of a road. This stately old brick building sported a funky art deco sign and the year 1888. The company, our guide said, provided power for arc lights – blue-hued lamps that were used mainly for outdoor lighting. The building had since been transformed into apartments. Here, our guide also told us about the blizzard of 1888, which was the event that prompted New York City to legislate putting all of Manhattan’s wiring underground.

Excelsior Power Company building

Excelsior Power Company building

Excelsior Power Company building

Then we walked south on William Street. Along the way I snapped photos of the overlapping collage of buildings above, some old and some new. I could identify some of them, but in general I don’t know my way around the financial district’s winding, narrow, named streets too well.

Buildings on our walk

Buildings on our walk

Buildings on our walk

We turned onto Wall Street and made our final stop. Across from us at the scaffolding-covered 23 Wall Street, Edison had demonstrated an electric lightbulb to Mr. J.P. Morgan. The tale goes that Edison’s assistant, with his watch synchronized, threw a switch to turn on power to this light as a punchline to Edison’s talk with Morgan.

By 1892, guide said, Edison left the power business, having been forced out in a merger. He continued work on other influential inventions afterwards.

And with that, our tour was over. I said rather hasty goodbyes (I was in a hurry to get cold water, air conditioning, and lunch in that order) and headed off to a subway station to fulfill those tasks. My head was full of knowledge and my notebook full of notes after this interesting and educational day. I only wished it would have been 10 or 15 degrees cooler!

See a map of Cliff Street substation walking tour.

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