What is the voltage used for a M3900 series phone?

[GuardguyMO]

I am having some problems with some external buildings getting their phones knocked out during storms. I am looking at putting some ITW Linx 66 Block Ultralinx Protectors at the entry panels. The have 39v and 27v clamping type protection. Which ones should I use for digital phones. I have searched all over the internet for the digital phone voltage specs to no avail.

 

[NortelGuy1979]

Check NN43001-311 "Circuit Card Reference" for the NT8D02 digital line card; does that have the info you need?

There's a table; one of the fields is "power supply" which says +5VDC, +/- 15VDC, and +/- 10VDC. Would that make sense?

Matthew - Technical Support Engineer Sr.

http://www.linkedin.com/in/matty79

 

[nogden]

It seems like I usually measure about 28 volts on digital ports. Therefore, of the two options, the 39 volt clamping protector would be most appropriate. However, that still may be unnecessarily low. I have the standard five-pin protectors in our building entrance terminals. I believe they clamp around 250v or so and I've never lost a phone or port in a storm. Some of our phones are just protected by old carbons and again, never lost a phone in a storm.

If you are losing phones, I would be more concerned that your building entrance terminals are either not wired correctly or (more likely) not grounded properly. I found that once -- a BET was grounded to the phone company's protector, except that the phone company protector ground was disconnected, so our BET wasn't grounded. Still, adding secondary protectors is not a bad idea at all.

-Nelson