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How to install a video door phone

Updated: 22 October 2026

The carton is open, the leads look about four inches long, and the electric lock you expected is not in the bag. How to install a video door phone, for the wired kits in this set, is a sequence: read the core count, check the plug line, prove call and picture on the short lead, and only then run cable. You stop when the job becomes a new mains circuit or a lock on a door you use to get out. This page does not give a terminal diagram. Prices stay on the [Door intercom comparison](/hub/electronic-surveillance/door-intercom). Products Compared editorial team, 19 October 2026. Not a lab test. A qualifying amazon.co.uk purchase can earn us a commission.

The carton is open, the leads look about four inches long, and the electric lock you expected is not in the bag.

Our top picks

EZVIZ EZVIZ CP5 7-inch Wi-Fi video door phone

Best overall

EZVIZ EZVIZ CP5 7-inch Wi-Fi video door phone
9.2/10about £161.49
View offer
TMEZON TMEZON MZ-V20 7-inch wired video intercom

Best value

TMEZON TMEZON MZ-V20 7-inch wired video intercom
8.8/10about £79.99
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QingTianTongYun QingTianTongYun 4.3-inch wired video door phone

Alternative

QingTianTongYun QingTianTongYun 4.3-inch wired video door phone
8.4/10about £79.99
View offer
On this page
  1. 1.What the box does not contain
  2. 2.Bench test, then the route
  3. 3.Power, and the point you stop
  4. 4.The unlock button is not a lock

What the box does not contain

On the TMEZON MZ-V20 the extension cable is not in the box. A 4-pin connector is supplied, and a UK review describes the supplied leads as about 4 inches. The two-monitor kit lists a 1 m test cable, which will not reach a real front door. The electric lock is not in either included list. The QingTianTongYun parts list includes one 3-pin UK adapter, and a feature bullet says the power supply is not included, so do not assume the adapter is present until you open the carton. The lock and the exit button are excluded. The EZVIZ CP5 field reads "36 EU", which does not confirm a BS 1363 plug, and the lock and the microSD card are not stated as included. A UK review says the install needs two wires indoors and that the listing had no wiring diagram for the old cable. Shop the missing cable, a plug situation you understand, and, if you need release, a strike you have not yet wired. If the only cable in the wall is one pair, do not force a four-core kit onto it. That choice belongs on the door entry system buying guide.

Bench test, then the route

Connect the outdoor station to the monitor with the short lead that came in the box, on a table, before you chase plaster. Power the monitor, call from the outdoor button, and check both ways of speech and the picture. On the TMEZON, UK reviews say the colour codes have to be learned before it feels easy. Learn them on the bench, not with your arm in a cavity. If the bench call fails, the fault is the kit or the plug, not the wall. TMEZON is 4-wire. QingTianTongYun states a maximum of 100 m on 4-core cable. The CP5 listing states 2-wire installation and 4-wire compatibility. Do not copy Videx metre figures or terminal names onto these ASINs. Fix the outdoor station where a visitor can reach the button and the lens sees your step rather than the street. If the door is a communal entrance, stop and read door intercom for a flat.
EZVIZ EZVIZ CP5 7-inch Wi-Fi video door phone

Testsieger

EZVIZ EZVIZ CP5 7-inch Wi-Fi video door phone
9.2/10about £161.49
View offer

Power, and the point you stop

In England, Approved Document P treats a new circuit, a consumer-unit change, or work in a bathroom zone as notifiable. A monitor on an existing socket is a different case, and the circuit still has to be safe under BS 7671. Wales has its own Part P. Scotland and Northern Ireland use other building-standards systems, so an English sentence is not a nationwide permission. The two-monitor TMEZON box includes two power supplies, and a UK reviewer said each screen needs its own supply. The CP5 plug is unconfirmed in this scrape. Stop and call a competent electrician for a new circuit, a consumer-unit change, a cable through a bathroom zone, or live conductors you cannot identify in an old loom.

The unlock button is not a lock

Pressing unlock closes or opens a contact. It does not contain the strike. EZVIZ's CP5 page describes dry-contact outputs and says the strike must stay within the current they state. A Videx VR4K manual, used only as an example of that idea, also ships without the lock. Those Videx terminals are not the TMEZON pinout, and this page will not draw one. A strike needs a supply that matches 12 V or 24 V. None of these listings is a wiring diagram for that match. Fail-secure locks need a mechanical way out. Fail-safe locks need a proper manual release. Do not put the only escape route on the unlock button. BS 7273-4, for releases on escape routes, is a locksmith and fire-door job. If the button does nothing after a bench call, the lock was never in the box.

Common questions

What do I buy before the drill?
The cable the listing's core count requires, because the TMEZON extension is not included. Confirm the plug line before you promise a socket install. Buy the lock only if you need release, and treat it as a separate item.
Is this notifiable under Part P in England?
A new circuit, a consumer-unit replacement, or work in a bathroom zone is the notifiable set in Approved Document P. A monitor on an existing socket is a different case and still has to be safe.
What is different in Scotland?
Scotland does not use England's Part P handbook. Building standards there are a separate system, as they are in Northern Ireland, and Wales has its own Part P. The bench test itself does not change.
The unlock button does nothing. What is missing?
The electric lock is not in the box. The monitor can only operate a contact. If the door is your escape route, stop and speak to a locksmith rather than improvising a latch.
What if the only cable in the wall is one pair?
A four-wire TMEZON or a four-core QingTianTongYun kit is the wrong match unless you pull new cable. The CP5 listing is the video kit here that states 2-wire installation. If you cannot pull cable at all, that is a radio kit, not a longer chase.

Related pages

Wired vs wireless door intercom

Door intercom

Best video door phone UK: CP5 versus TMEZON MZ-V20

Door entry system buying guide: cable, plug, locks

Door intercom for a flat: consent before any screw

Sources

Public UK sources and the amazon.co.uk listings compared on this page. Listings captured 19 October 2026.

  1. BSI, BS EN 62820-1-1:2016+A11:2021 (retrieved 19 October 2026)
  2. Approved Document P (England) (retrieved 19 October 2026)
  3. Tameside Building Control Note 20 (retrieved 19 October 2026)
  4. ICO, home CCTV (retrieved 19 October 2026)
  5. GOV.UK, domestic CCTV (retrieved 19 October 2026)
  6. IEC IP ratings (retrieved 19 October 2026)
  7. Consumer Rights Act 2015, section 9 (retrieved 19 October 2026)
  8. NACD, emergency egress note (retrieved 19 October 2026)