Comcast is introducing a "data meter" to broadband customers in Washington state on Tuesday to help customers keep track of broadband consumption -- and avoid hitting the company's controversial data usage cap.

In October 2008, the company began limiting residential broadband customers to 250 gigabytes of data usage per month. Before that, the company had periodically cut off service to people using too much broadband, but hadn't specified an amount, drawing complaints that it was throttling users.

After the limit was specified, customers asked Comcast for some kind of meter so they could keep track of their usage, spokesman Steve Kipp said in announcing the meter.

"Our hope is that this meter will help give our customers a better picture of their overall bandwidth consumption. We believe many will be surprised by how little data they actually consume,'' he said in the release.

Comcast will send broadband customers an e-mail Tuesday about the meter, shown here:

UPDATE: Kipp said about 40 percent of customers received the meter on Tuesday and the rest should have it Thursday.

Kipp said most customers don't consume enough data to be concerned; customer consume at the median from 2 to 4 gigabytes per month and 99 percent use less than 250 gigs per month.

"For the fraction of less than 1 percent of our customers who are concerned about exceeding our excessive use threshold, we believe this meter will help them monitor and calibrate their usage," Kipp said. "It may also help them identify potential problems such as the presence of a bot or virus or excessive use of their bandwidth via an unsecured wireless router."

Comcast imposed the "excessive use program in order to provide a high-quality online service for all of our customers because extremely high-data users can negatively impact the experience for other customers,'' he said.

Washington is the company's second market to receive the meter, which was introduced earlier in Portland.

A few details Kipp called out:

-- The meter will measure all data usage over a cable modem, including data used by all computers, consoles and devices in a home that go online via that modem.

-- The meter will display usage on a calendar month, not the monthly billing cycle, which may be different. it will udpate about every three hours.

-- The meter will "display usage conservatively in favor of customers" by rounding usage down to the nearest gigabyte, rather than up, the release said.

-- Comcast hired a consultant, NetForecast, to analyze the accuracy of the meter during a test period last summer.

Here's how to find the meter on your Comcast account, according to the release:

"Customers can access the meter by logging into Comcast Central at http://customer.comcast.com and clicking on the 'Users and Settings' tab. There, they will see a link to 'View details' in the 'My devices' section (located toward the upper right hand of the screen) that will take them to their data usage details page. The meter will first show usage in the current month. Over time, it will show the most recent three months of usage (including the current month)."

So what happens if you go over the 250 GB limit?

You may get a call from Comcast, and put on a sort of probation. If you cross the limit again within six months, Comcast will cut off your service for a year.

Kipp said the callers from the "Customer Security Assurance team" will say how much data was used and "try to help you identify the source of excessive use and ask you to moderate your usage, which the vast majority of our customers do voluntarily ... We know from experience that most customers curb their usage after our first call."

"Our practice for the past several years has been to call only our heaviest data users, and this practice remains the same now that the 250GB data usage threshold is in effect," Kipp wrote. "We may change our practice but will, of course, provide notice to the customer of any change."