Telephone cable voltage query

[luminaire]

I am connecting a speech dialler from an alarm panel and when I checked the voltage of the telephone cable it only measured 39.4v. Will this be sufficient not to cause any problems later on.
The telephone on the extension works OK.

 

[breezer]

try it ands see.

i take it you have a non BT supplier?

 

[luminaire]

try it ands see.

i take it you have a non BT supplier?

The supply is BT. The guy who installed the telephones put in a lot of extensions, so that in order to dial out you have to dial 9 first to get an outside line.
HTH.

 

[breezer]

so you have your own "exchange" then

you will also need to make your speach dialer dial 9 first

 

[AlanE]

A better idea would be to wire the alarm, as an extension, to the main incomming circuit for two reasons:

1. Speach dialer probably has battery back up supply and in event of power failure it would work whereas the PABX would fail. Even if PABX switches one extension to its input system would still fail as speach dialer would now send a 9 prefix onto BT line resulting in a number unrecognised error message.

2. Prefix 9 on speach dialer would also need a few seconds pause before dialing outside number to allow time for line to be siezed properly.

 

[JOHNBOY42]

I am connecting a speech dialler from an alarm panel and when I checked the voltage of the telephone cable it only measured 39.4v. Will this be sufficient not to cause any problems later on.
The telephone on the extension works OK.

Check the voltage again you should be getting between 49-53v on a pstn line,less than this will give you problems

 

[Lectrician]

I am connecting a speech dialler from an alarm panel and when I checked the voltage of the telephone cable it only measured 39.4v. Will this be sufficient not to cause any problems later on.
The telephone on the extension works OK.

Check the voltage again you should be getting between 49-53v on a pstn line,less than this will give you problems

He does not have a PSTN Line, it is an extension from a PBX.

Put the dialler directly to the line. If it has line seize, it will be able to cut off all calls and then sieze the line to dial, it wont be able to do this if it is on the extension side of the PBX. The voltage you mention is typical of a PBX.

If you go line side, forge the 9. If you go extension side, you need to put a 9 in.

 

[luminaire]

Thanks for all your replies I can see now that I could have problems in the future unless I get it a direct line connection.