Independent comparisons. We may earn from shop links. More info

How to wire a 1 way door entry system

Updated: 22 October 2026

You have a one-door kit on the bench, or you are about to buy one, and the dangerous part is not the speech button. It is the wrong cable, both volumes turned up, or a 230 V terminal treated as a Saturday job. How to wire a 1 way door entry system, for the audio kits Bell’s diagrams describe, starts with the pair in the wall and stops at the mains. This page is from Peter F., editor for DIY & tools, using Bell’s PD-151 and PD-084 sheets and the amazon.co.uk notes. It is not a colour recipe for every brand. The kits are ranked on the [1 apartment intercom system comparison](/hub/electronic-surveillance/1-apartment-intercom-system).

You have a one-door kit on the bench, or you are about to buy one, and the dangerous part is not the speech button. It is the wrong cable, both volumes turned up, or a 230 V terminal treated as a Saturday job.

Our top picks

ANJIELO SMART ANJIELO SMART wireless video intercom

Best overall

ANJIELO SMART ANJIELO SMART wireless video intercom
4.5/10about £329.99
View offer
Bell System Bell 901 1-way audio door entry

Best value

Bell System Bell 901 1-way audio door entry
7.8/10about £88.46
View offer
TMEZON TMEZON 7-inch video kit, two monitors

Rank 3

TMEZON TMEZON 7-inch video kit, two monitors
8.4/10about £135.99
View offer
On this page
  1. 1.Cable the speech actually needs
  2. 2.Where the supply goes
  3. 3.One handset first, then the volumes
  4. 4.A 4-wire screen is not this diagram
  5. 5.When you put the screwdriver down

Cable the speech actually needs

Bell’s 1-way diagram for the 901, VRK1 and BL1 calls for CW1308 or Cat5e. The red and orange cores are used as a pair, which is what keeps the speech intelligible. Alarm cable is the mistake that looks close enough in the hand. One UK review of the Bell 901 listing says the wires you fit are coloured and the instructions are in black and white. Use the cable the manufacturer names before you strip anything. Do not invent a colour map for a video kit from this audio diagram. The optional release on PD-151 is the Model 203, for an inward-opening door with a surface night latch and a little play in the strike. That is a lock choice, not a reason to change the speech pair. If you are still deciding whether the door can take a release, read the electric door release for a door entry system page before you cut the frame.

Where the supply goes

The power supply sits indoors, where you can reach it and where it stays dry. Bell’s PD-151 and PD-084 both tell you to isolate live and neutral, and both say a competent person connects the 230 V side. Low-voltage terminals on the speech unit are the part a careful householder can follow on the diagram. The mains terminals are not a guess. Approved Document P, in England, makes a new circuit, a consumer-unit change, or work in a bath or shower zone notifiable. A plug-in supply on an existing socket, outside a bathroom, is often a different job. If you are adding a fused spur from a new breaker, stop and use an electrician. Mount the supply where the handset cable can reach it without a joint in a damp wall, and test one phone before you button the panel up.
ANJIELO SMART ANJIELO SMART wireless video intercom

Testsieger

ANJIELO SMART ANJIELO SMART wireless video intercom
4.5/10about £329.99
View offer

One handset first, then the volumes

PD-084 tells you to test one telephone on a short lead before you commit the rest of a larger system. For a single dwelling that is still the right order. Connect the handset on a short piece of the same cable, prove speech both ways, and only then pull the long run. If it fails on a metre of cable on the kitchen table, it will not improve inside a wall. The whistle is feedback, when the outdoor microphone and the indoor earpiece can hear each other. Damp weather makes it worse on the Bell reviews. Turn both volumes down, then bring them up until the speech is clear and the howl has not returned. If the short-lead test is clean and the long run goes dull, suspect alarm cable or a split pair before you condemn the handset.

A 4-wire screen is not this diagram

The TMEZON kit in this comparison is a 4-wire video set, not the Bell speech diagram. The box includes a 1 metre test cable, a 4-pin connector, two monitors and two power supplies. The extension cable is not included. You can prove one monitor on that short lead. You cannot treat it as the door run. A UK review fitted a second screen upstairs on an existing four-wire installation and needed one supply per monitor. Do not copy Bell red and orange onto the TMEZON terminals. If you are reusing four old cores, identify them with a meter and the sheet in the box. The LUCINE listing does not state a wire count. The ANJIELO seller text says no cable connection is required, which does not remove the mains plug on the indoor screen. The choice between a handset and a screen is on audio or video door entry.

When you put the screwdriver down

Stop when the work is a new circuit, a consumer-unit change, or anything in a bath or shower zone. Also stop for a fire door, a communal entrance, or any door you cannot open from inside without power. A competent person does the 230 V side. Low-voltage speech on the diagram is a different task from the mains terminals.

Common questions

Which cable for speech?
For the Bell 1-way diagram, CW1308 or Cat5e, with red and orange kept as a pair. Alarm cable is the wrong substitute. Use the cable the manufacturer names for the kit in your hand, and do not transfer Bell colours onto a video terminal block that the file does not colour-code.
Where does the power supply sit?
Indoors, dry, and reachable. Keep it off a wet porch floor and avoid a buried joint you cannot remake. The TMEZON box has two supplies, and a UK review used one per screen, downstairs and upstairs. The 1 metre lead in that box is a test lead, not the door run.
Who connects the 230 V terminals?
A competent person. Bell’s PD-151 and PD-084 say to isolate live and neutral before that connection. Low-voltage speech wiring on the diagram is a different task from the mains terminals. If you are unsure which terminals are which, stop before you energise anything.
What if it whistles?
Turn both volumes down, then bring them up until speech is clear and the howl stays away. A UK review of the Bell 901 fixed feedback that way, and damp weather makes it more likely. Maximum volume at both ends is how the whistle is built, not how it is cured. Start with the indoor volume, then the outdoor one.
Can you reuse four old cores for the TMEZON kit?
Only if they are the four cores that kit expects and you can identify them. A UK review did replace an older four-wire screen. A single bell pair is not enough. Do not assume the old colours match either Bell’s sheet or the TMEZON terminals. Use a meter and the sheet in the box.
Why is the 1 metre lead not the door run?
The TMEZON listing includes a 1 metre test cable and says the extension cable is not included. A metre will reach from a doorbell to a monitor on a table. It will not reach from a street door to a hall or a landing. Budget the extension before you mount the panel.
When do you stop and call an electrician?
When the work is a new circuit, a consumer-unit change, or anything in a bath or shower zone, which Approved Document P treats as notifiable in England. Also stop for a fire door, a communal entrance, or any door you cannot open from inside without power. Mains isolation is not optional while you just try a terminal.

Related pages

1 apartment intercom system buying guide

1 apartment intercom system

Audio or video door entry: when a screen is worth it

Best 1 way door entry system for a single front door

Electric door release for a door entry system in the UK

Sources

Public UK and maker sources from the research digest, used for this page in October 2026. Prices, stars and review counts are from the four amazon.co.uk listings captured on 19 October 2026. An IP54 or IP65 line is seller text. amazon.co.uk B0066PTTHI does not list a lock release. None of these listings shows a test to BS EN IEC 62820-1-1.

  1. BS EN IEC 62820-1-1:2026 preview (retrieved 19 October 2026)
  2. Bell PD-151 1-way audio diagram (retrieved 19 October 2026)
  3. Bell PD-084 801 DC wiring (retrieved 19 October 2026)
  4. Approved Document P (retrieved 19 October 2026)
  5. Approved Document B door fastenings (retrieved 19 October 2026)
  6. ICO, home CCTV systems (retrieved 19 October 2026)
  7. GOV.UK, domestic CCTV (retrieved 19 October 2026)
  8. Door Entry Direct, Bell 901 kit (retrieved 19 October 2026)