The oversize black-and-red switch Mayor Ed Lee flicked on Dec. 17 didn’t actually turn anything on. But it did mark the official launch of The City’s largest free Wi-Fi service, which runs along Market Street from the Castro to The Embarcadero.

Now, more than a month into the pilot program with Ruckus Wireless, about 250 people use the service daily, according to The City, which hopes to grow that number with increased awareness. But the system’s speed, ease of use and quality have yet to be tested.

With that in mind, The San Francisco Examiner set out recently to get a sense of who’s using the service and how well it’s operating.

At four of five random sites along Market Street, an iPhone 4s was able to play YouTube clips of “New Girl” with little delay and no buffering of the stream.

The most glitches in the service occurred at the foot of Market Street in front of the Ferry Building. No YouTube clip would play and a download test was fairly slow on the iPhone, but an Android phone worked well.

Not far away at the Embarcadero BART station, YouTube played just fine on the iPhone.

While the signal was strong and seemed to do its job, that made no difference to people like Trung Thanh, an employee at nearby Soup Junkie, who said he “had no idea” the free Wi-Fi existed.

Down the road at Powell and Market streets, YouTube played seamlessly.

Thereabouts, Eric Rasmussen, a 56-year-old construction worker from Seattle, said he uses the service often.

“The closer you are to Market Street, the better it is,” he said.

His friend Bob Lingle, 46, said it has worked fairly well for him as well.

“I think it’s awesome,” Lingle said.

Both men have used the service successfully for work to download architectural drawings and the like.

Across the street from Twitter’s headquarters, at the Mavelous cafe, barista Preston Yoder, 26, said he has used the service.

“Works on the phone, amazing s—,” he said.

Across the street, right below the Twitter sign, a powerful signal seamlessly played a video.

At the intersection of Market and Castro streets, YouTube clips also played without fault.

Anselmo De Yermosa, a 24-year-old concierge from New Mexico, said he’s known about the free Wi-Fi for some time. While he doesn’t use it often, he said, it’s been fast the times he has.

The last time De Yermosa logged on was Tuesday, he said. There was a delay on the subway so he logged on to find out what was causing the slowdown.

“The Wi-Fi worked, but I couldn’t find a solution to the problem,” he said.

If you want to try the free Wi-Fi

To log on, simply use the “_San_Francisco_Free_WiFi” network that pops up on your phone, computer or tablet.

The open network is listed as one of the wireless options on any device, and the service is free of ads.

Unlike cellphone service, the free Wi-Fi works best when you stay in one place. Since each of the 400 sites send out individual signals, when you move up and down the street your device must connect to each individually.

The service works better on laptops than smartphones because of different antenna sizes.

The Market Street network was made possible with a donation of hardware from Bay Area-based Ruckus Wireless.

In six months, a separate Wi-Fi service made possible through a $600,000 grant from Google is expected to launch in 31 public spaces throughout San Francisco.

The City says its total wireless network maintenance budget for the upcoming fiscal year, including the new Market Street service, is $120,000.Bay Area NewsMarket Street free Wi-FiRuckus WirelessSan Francisco free Wi-Fi

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