Maximum telephone points

Discussion in 'Electricians' Talk' started by 1acer, Feb 8, 2011.

  1. 1acer

    1acer New Member

    Can anyone help? I need to install 19 telephone points into a property, whats the maximumyou can have on a line?  Is it best to have all 19 go back to a central point?
     
  2. wally

    wally Screwfix Select

    You can have 19 if you want as long as they are only sockets but you can only use 4 ren or possibly 5 ren (someone else will correct me if im wrong)     Most equipment is rated 1 ren .    Otherwise you might need other equipment installed
     
  3. 1acer

    1acer New Member

    Yeah its only for a phone. So if i run a cat 5 from a central loctaion to each of the 19 points, everything will be hunky dorey ;)
     
  4. JC2779

    JC2779 Member

    In terms of wiring then yes. but as Wally said you will only be able to use a limited amount of equipment.
     
  5. Lectrician

    Lectrician Screwfix Select

    How would you connect your 19 cables at your 'central location'?

    If you are going to do it that way go google "cat5e flood wiring".

    You can have a REN of 4 (the REN is a term used to indicate how much ring current is available to drive ringers in phones).  If you wanted more phones you would use a "REN booster".  These are mains powered and provide the additional ring current.
     
  6. sinewave

    sinewave Screwfix Select

    If you have too many sockets, the phone won't ring.
    It's all about Ringer Equivalence Numbers (REN). Most telephone handsets have a REN of 1, some old fax machines are 1.5 or even 2.

    BT guarantee a REN of 4, meaning you can have 4 phones plugged in and they'll all ring.
    Each master socket is REN1.
    So if you have 4 master sockets, you can have 0 phones ringing.
    More than 4 normal (non-mains) phones and you'll encounter ringing problems.

    You can get up to 6 or so cordless units that'll work from 1 main base station with a REN of 1 so one assumes that 4 base stations with 6 phones a piece might suit.

    If your client needs 19 hard wired BT points then you'll need to look at a proper phone system running CAT5E etc to each outlet.
     
  7. Southspark

    Southspark New Member

    A PABX telephone line (BT for example) typically has a REN of 4. A typical telephone handset has a REN of 1. Each line should have only one master socket and an unlimited number of secondary sockets. You may connect up any number of 'appliances' totalling REN4 to guarantee that they will operate correctly, regardless of which socket they are in. More than one master socket on the line, or more than REN4 could cause ring trip. (receiving phone rings once then cuts out, but the caller hears a continous ring though). There is a limit to the total length of cable run, but in most situations this will not be a consideration. A single connection point is not recommended, just daisy chain the sockets using 4 core, single strand telephone cable, punched into IDC (insulation displacement connector) terminals and you should have no problems.

    Wiring as follows:      Blue/White stripe - 2     White/Blue strip - 5     Orange/White Stripe - 3 (ringer line)   No other connections required.

    Hope this helps.
     
  8. Mountain Man

    Mountain Man New Member

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