One accurate time, building-wide

It can, and often without pulling new cable. There are three distribution methods:

• NTP / PoE clock faces — use your existing structured cabling. A single Cat cable carries both data and power; no separate outlet circuit is needed per clock face. This is the first option we look at in an existing building.
• Wireless (radio-synchronised) clock faces — fed from a central transmitter, with no cable running to the clock face at all.
• Classic impulse / AFNOR distribution — a single twisted-pair telephone cable carrying many clock faces on one line. This is the only method that requires new cable; it is generally chosen for new buildings or ones where the line is already in place.

So the answer depends not on the building but on your network infrastructure. During the site survey we first look at your existing cabling category and PoE capacity.

In order:

• Number and type of clock faces — indoor / outdoor (weather-resistant), single-face / double-face, analogue / digital.
• Distribution method — PoE noticeably lowers installation cost; pulling new cable is the most expensive option.
• Master clock class — a simple NTP server, or a nanosecond-class PTP (IEEE 1588) grandmaster.
• Redundancy — dual master clock, dual antenna.
• GNSS antenna and cable distance — if the run from the roof to the system room is long, a line amplifier or DC injector is needed; this item looks small but is a real cost in long buildings.

The sequence of work is fixed: antenna mounting on the roof, commissioning the master clock in the system room, the distribution line, clock face mounting, and acceptance testing. Most of these steps are done while the facility keeps running.

Where a shutdown is needed, it is only for the power to the relevant panel or line; we schedule these between shifts, on a weekend, or during a planned stoppage. Because clock face mounting proceeds room by room, the whole facility never stops at any stage.

The installation time varies with the size of the project; we provide a schedule specific to your scope as an appendix to the quote.

For the quote, a floor plan and the points where clock faces are wanted are enough. Design also requires the following:

• Rack space (typically 1U) and power for the master clock in the system room.
• A mounting point with a clear view of the sky for the GNSS antenna on the roof, and a cable route.
• If NTP will be used, UDP 123 opened by your network team — on corporate networks this port is very often closed by default, and it is the item that most often holds up the project.
• An internal "approved time source" decision. ISO 27001:2022 A.8.17 already requires system clocks to be synchronised to an approved source; a master clock is the concrete step that satisfies this item.
• Access to cable/power routing at the clock face points.

When the master clock loses its GNSS reference, it does not stop: it keeps counting on its internal oscillator — this is called holdover. Accuracy degrades gradually depending on the oscillator class; more stable oscillator models are chosen for critical sites.

In critical facilities we build two layers of redundancy: dual master clock and dual antenna. On networks using PTP, the backup grandmaster takes over automatically.

How a clock face behaves on signal loss depends on the model (some stop at the last correct time, some keep running on their own quartz). We state the behaviour of the clock face you choose in writing in the quote — we do not leave you to guess.

On the response side: on sites under a maintenance agreement, the on-site response time after a fault is reported is defined in the contract.