Training Spotlight: Determining the MEW Factor for Your Central Station

By Josh Tafoya, Bold Technical Trainer

As UL requirements for Monitoring Stations evolve, from time to time, we hope to update you with information or resources that you might find useful. As you likely know, Manitou is certified under the UL 1981. The 1981 is specifically geared towards Alarm Automation Software, the requirements for the software and hardware, and the procedures when using Alarm Automation software. The MEW factor is covered on the UL 827. Even though the UL 827 does not govern the software, there are some things, including the MEW factor, where the required information is obtained from Manitou. I’m going to attempt, without plagiarizing the 827, to explain the numbers the UL is looking for.

MEW stands for Monitoring Equivalent Weight. Despite the numbers for the MEW factor coming from the Manitou software (or rather the database, at the moment), the MEW factor is used to determine the hardware requirements for a Central Station. As far as the MEW factor is concerned, there are three types of accounts. I am going to do my best to communicate them here since the UL uses different terminology than Manitou uses.

The types of accounts are:

  • Residential accounts (In Manitou, these are Residential Accounts whose monitoring status is set to ‘Active’)
  • Commercial Inactive Accounts (Stay with me here… this is where the UL terminology differs from Manitou. In Manitou, these are Active Commercial Accounts with no Supervised Open/Close service)
  • Commercial Accounts with Open/Close (In Manitou, these are Active Commercial accounts with a Supervised Open/Close service. More to the point, the number of Supervised Areas on Active Commercial Accounts – refer to UL 827 17.4.2c)

Because the UL gives a different weight to each type of account, we come to the point now where we are forced to do some math. Don’t worry, though…it’s simple multiplication. As far as the MEW factor is concerned, Commercial Inactive accounts have a weight of one. Residential accounts are weighted at one-third of a Commercial Inactive account, and Commercial Accounts (Areas) with Open/Close are weighted at three times a Commercial Inactive account.

Confused yet? Don’t worry! An example table is shown below:

mew factor chart


As you can see, the weight of each type of account is calculated in the right-most column. The very last value in the right-most column is the MEW Factor. The UL will use this, as previously mentioned, to determine your hardware needs. Again, my goal here is not to reproduce the UL 827 here, so refer to your copy, or talk to your UL inspector about what the MEW Factor means for you.

At the moment, there is not a report built into Manitou which can provide this data. The good news is until we have a proper report, we can query the database and provide you the results ahead of a UL inspection. The best thing to do, with as much advance notice as possible, is to open a ticket with Support. Since it’s fairly easy to get this information, in most cases it should be handled in short order.

I’d like to give kudos to a number of people who worked on the query we use to get this data, including Bold staff members Scott Bordeau, Amy Condon, Shaun Blair, and Nial MacDonald.

As the UL requirements evolve, we hope to continue to keep pace. We always appreciate feedback and would love to hear from you!