Short answer
An intercom installation in a block of flats consists of a door entry panel at the entrance, a power supply in the block's meter cupboard, a riser cable through the building and an indoor station in each home. When replacing, the question is always whether the existing riser cable can be reused. With two-wire systems it usually can, and then the disruption stays limited.
Who this article is for For boards and managers of owners' associations (VvE). For a house with one doorbell, connecting a video doorbell is the right article.
The four parts
The door entry panel. At the entrance, with the buttons, the name plates, the loudspeaker and, with video, the camera. This is the part that suffers most from the weather and from hands.
The power supply and the control unit. In the block's meter cupboard. This holds the logic that decides which home is called and that controls the door release.
The riser cable. The cable that runs through the building to all the homes. This decides whether replacement turns out easier than expected.
The indoor stations. The unit in the home, from a simple handset to a screen with video.
The riser cable decides everything
In old systems there is sometimes a separate core per home to the door entry panel. With eighteen homes that is a thick bundle, and replacing it then means pulling cable through riser shafts that are often full.
Modern systems use two wires for everything: power, speech, video and the door release. If there is a two-core cable in the building that reaches all the homes, a modern system can almost always go on it, with video, without cutting into walls.
That is the first question I answer on site, and usually it is good news.
What replacement means in practice
- Survey: what is there, what condition the door entry panel is in, how many homes
- Proposal with options: audio or video, which brand, what can be reused
- Decision at the meeting, usually with a quote the residents can look at
- Installation: door entry panel and control unit first, then the indoor stations home by home
- Handover and explanation for each resident
Residents only need to be at home for their own unit, about half an hour.
The disruption is limited if the riser cable stays: residents only need to be at home for their own unit, about half an hour per home.
What to look for when choosing
- parts in the long term: choose a brand that will still be available in ten years
- name plates: digital display or engraved, that saves hassle when people move
- door release: does the existing one fit, or does it need replacing too
- postman and parcel services: a key switch or a separate code
- link to the phone: can be handy, but needs internet at the control unit
Maintenance
An outdoor door entry panel suffers from moisture and vandalism. Checking it once a year, inspecting the cable entries and testing the buttons prevents the complaints that otherwise trickle in one resident at a time. For owners' associations (VvE) I include that in a maintenance agreement.
From my own work
In a block of eighteen flats the intercom was from 1994 and parts were no longer available. The riser cable turned out to be a neatly laid two-core cable per floor. That meant a modern two-wire system could go in without cutting into anything. In two days all eighteen indoor stations were in, with video, and the residents only had to be at home for their own unit.
When to call an electrician
- The intercom is old and parts are no longer available
- There are complaints about poor audio or calls not coming through
- The board wants to know what replacement will cost
- Video needs to be added on the existing cabling
I first look at what is there, because that determines the price. See business and request a quote.
Frequently asked questions
Does the whole installation have to go if something is broken?
Rarely. Often it is the door entry panel or the power supply. Only when parts are no longer available does replacement become worthwhile.
Can video be added on the existing cabling?
With a two-core riser cable usually yes, because modern systems send video and power over the same two cores.
How much disruption does replacement cause for residents?
If the riser cable stays: about half an hour per home. They only need to be at home for their own unit.
Further reading
Doorbell transformer: what it is for and why your doorbell is not working
If your doorbell is not working, it is usually the push button and not the transformer. Search in this order and you will usually have it within a quarter of an hour.
The intercom is not working: troubleshooting in four steps
If it does not work in one home, the problem is in that home. If it works for nobody, the problem is at the entrance or the power supply.
Replacing a doorbell or chime: what to look out for
Check the voltage of your transformer before you buy a chime, and where you will hear it. Those are the two things that go wrong.
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