Communication Systems in Confined Spaces

Reliable communication between personnel inside a confined space and the top man is critical for safety.
Communication methods include voice, two-way radios, wired intercom systems, and tug-line signals.
Voice communication fails in deep shafts, long culverts, and noisy environments with running water or plant.
Two-way radios may not work underground due to signal loss in concrete, steel, or deep structures.
Wired intercom systems provide the most reliable communication in deep or complex confined spaces.
Tug-line signals are a backup method using pre-agreed rope pulls between the entrant and top man.
The communication system must be tested before entry begins and checked at regular intervals during work.
Loss of communication is grounds for immediate withdrawal from the confined space.
The Confined Spaces Regulations 1997 require suitable arrangements for communication during entry.
Emergency signals must be pre-agreed so the top man can distinguish routine messages from distress calls.

Enable rescue	Without working communication, the top man cannot detect a problem inside the space, delaying rescue and costing lives.
Legal requirement	The Confined Spaces Regulations 1997 ACoP requires that suitable communication is maintained throughout confined space entry.
Changing conditions	Atmospheric conditions in confined spaces change rapidly. Communication allows immediate warning and evacuation orders.

Do

Don't

Test the communication system before anyone enters the confined space.
Agree emergency signals that clearly distinguish distress from routine communication.
Use wired intercom systems in deep shafts, tunnels, or signal-dead zones.
Carry a backup communication method in case the primary system fails.
Check communication at regular intervals throughout the entry work period.
Withdraw from the space immediately if communication is lost for any reason.
Brief all team members on the communication signals and methods before entry.
Ensure the top man can hear and respond to entrants at all times.
Use intrinsically safe communication equipment in potentially flammable atmospheres.
Record the communication methods and test results on the entry permit.

DON'T enter a confined space without testing the communication system first.
DON'T rely solely on voice communication in deep or noisy confined spaces.
DON'T use non-intrinsically safe radios in spaces with flammable atmosphere risk.
DON'T continue working if you lose contact with the top man at any point.
DON'T assume two-way radios will work underground in concrete or steel structures.
DON'T change the agreed emergency signals during the entry without a full re-brief.
DON'T allow the communication system battery to run flat during the work period.
DON'T ignore failed communication checks; withdraw and resolve the problem first.
DON'T shout as your only means of communication in long culverts or pipework.
DON'T skip the communication test because you used the same system yesterday.

See also: Confined Space Entry Procedures | Top Man and Entry Controller Duties

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