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urelectrician, Contractor
Category: Home Improvement
Satisfied Customers: 3538
Experience:  Certified Construction Manager & Licensed Electrician
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im trying to wire my intercom system, i have an bells 801 intercom.

Customer Question

im trying to wire my intercom system, i have an bells 801 intercom. i know the blue wire goes to the Z, orange wire goes to the O and the green goes to the I, i then have 3 remainding wires 1 white/green, 1 white/ blue and 1 white/orange i need to know which wires go to the R connection and the T connection any ideas?
Submitted: 4 years ago.
Category: Home Improvement
Expert:  Tommy Tesla replied 4 years ago.

Hello, my name is XXXXX XXXXX I am here to help you with all your electrical needs. I would like to thank you for choosing Just Answer. What we need to do to figure this out is look closely at the wiring diagram, depending on where that intercom wire originates from you need to go to that source and look at what terminals the wires are under. So for R that wire goes to the speech unit..go to that and look at color scheme. Same for T that wire also goes to speech unit. To double check that these are in fact the same wires you can use a multimeter to check them if you know how to do this,if not I will instruct you.

Customer: replied 4 years ago.
I can't look at the source as its a communal box and their is no way of opening it unfortunately.
Expert:  Tommy Tesla replied 4 years ago.

I would not no the color code the electrician used originally. I am not familiar with a communal box,can you post a picture?

Customer: replied 4 years ago.
I don't appear to be able to provide you with a picture of the box, sorry. It's a six buzzer button system as all the intercoms are connected to it in some way, my flat is a six ex council block that used the old elvox intercom system. Hope that info helps.
Expert:  urelectrician replied 4 years ago.

Hello my name is XXXXX XXXXX I will be happy to answer your home improvement or electrical question


1) You mention that you have 3 remaining wires. Are these station wiring that originates from the communal box?


2) Are these in pairs? ie, Do you have a white/blue paired with a blue/white, a white/orange paired with a orange/white and a white/green paired with a green/white? I am trying to determine if you have a standard telephone type of cabling that utilizes these colors?


2) How many handsets are you trying to connect?

Customer: replied 4 years ago.
Hi there,
It looks like they all originate from communal box.
I do have those wires with those colours.
I'm trying to rewrite one intercom.
Hope this helps.
Expert:  urelectrician replied 4 years ago.

1) OK, very good... thanks for the reply


2) In the standard telephony color code. the wire pairs start out as follows in sequential order: Line 1 will be the blue pair, Line 2 will be the Orange pair and Line 3 will be the green pair. Since you are rewiring one intercom, most likely you just need the white/blue & blue/white pair. Refer to the color code breakout below:


White/Blue = Tip or Transmit

Blue/White = Ring or Receive


White/Orange = Tip or Transmit

Orange/White = Ring or Receive


White/Green = Tip or Transmit

Green/White = Ring or Receive


3) Not sure what term they used in the directions, but the industry standard is T for Tip or Transmit and R is for Ring or Receive.

Hope this helps.........If you have any additional questions, let me know and I'll be glad to answer them for you.


Otherwise, don't forget to rate me before you log Off.

The next time you have an electrical question, you can also request for me at:

Customer: replied 4 years ago.
Hi Kevin,
Thanks for that info but now I'm confused because I have 6 wires and only 5 connections to put in, the connections are Z, T, O, R,and I. I believe Z is for the lock, T for speaker, O for communication, R for microphone and I for buzzer so what colour goes where?
Sorry if its easy.
Expert:  urelectrician replied 4 years ago.

1) I was unable to locate a wiring diagram on the internet for your particular model. Any chance that you could scan or take a picture of the diagram and post it here so I can view it?


2) Are the wires hard-wired directly to the intercom unit or does it have a wall jack that the wires terminate into?


3) T should be for the microphone and R should be for the speaker

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