Permit to work · 7 precautions · 1 critical

Breaking Ground / Penetration
permit to work

Drilling, coring, fixing into, or penetrating any surface where buried/hidden services may exist.

These are the precautions the issuer confirms before signing. Each one says what good looks like, when it passes, the regulation it rests on and how it usually fails. Critical precautions are marked: if one cannot be confirmed, the permit is not issued.

Precautions before issue

  1. 1.
    Service drawings obtained
    What to look forFor wall/floor/slab penetrations: as-built drawings showing buried services in slab (post-tension cables, conduits, drainage), in walls (electrical, data, heating), and behind ceilings. For floors: post-tension survey if PT slab. Plans cross-referenced to a non-destructive survey (ferroscan/GPR) before drilling. Drawings <12 months old where building is occupied / changes recent.
    Acceptable whenAs-built drawings obtained AND verified by NDT (GPR, ferroscan, thermal). PT slab status confirmed (PT slabs require specialist methodology, drilling can release tendons). Drawings <12 months old or verified.
    StandardHSG47 4th ed. CDM 2015. PAS 128 underground utility detection. Concrete Society TR43 (post-tensioned).
    Common defectsPT slab drilled without identifying tendons, tendon released, structural damage and projectile riskDrawings ignored because "the wall is just blockwork", buried conduit cutFloor drawings show ducts at predicted depth but slab thickness varies, duct above predicted depth, struckDrawings out of date, recent services not shown
  2. 2.
    CAT and Genny scan of area completed
    Critical: a fail stops the work
    What to look forFor wall/floor penetration: GPR or ferroscan (Hilti PS 1000, Proceq, etc.) used for in-slab/in-wall services AND rebar density. CAT4 with calibration cert valid (annual). Multiple sweep angles (perpendicular and parallel to expected service runs). Operator trained (manufacturer course or equivalent). Mark-up showing every detected anomaly.
    Acceptable whenGPR/ferroscan calibration current. Multiple sweep angles. Anomaly mark-up on substrate before drilling. Repeated scan at depth as drilling progresses. Operator competent (trained).
    StandardHSG47 4th ed. PAS 128. EUSR Cable Avoidance / Locator schemes.
    Common defectsSingle-axis scan only, service running perpendicular to scan direction missedCAT scan in concrete (CAT designed for buried services in soil), wrong tool, unreliableGPR operator untrained, interprets reflections incorrectlyScan footprint smaller than drill areaCalibration cert expired
  3. 3.
    Area marked up, services identified
    What to look forSubstrate physically marked with paint/chalk showing each detected service, depth, and identification (e.g. "Cable LV 50mm deep"). Mark-up photographed and retained. Marks visible to the drilling operator at the time of drilling. Where uncertain, area marked "DO NOT DRILL, INVESTIGATE".
    Acceptable whenMark-up on the actual substrate. Identification + depth shown. Photographed for record. Drilling forbidden in unmarked or "investigate" zones.
    StandardHSG47. CDM 2015.
    Common defectsMark on a covering sheet, not the substrate, sheet removed, marks lostMark wiped off by cleaning, operator drills in cleaned zoneDepth not shown, operator drills past service depthNo mark for "do not drill" zones, operator assumes it is fine
  4. 4.
    Hand tools used within 500mm of services
    What to look forFor wall/floor: once a service is detected, the immediate surrounding area is opened up by hand (insulated chisel, hand drill, no impact / SDS / breaker) until the service is exposed and identified. ONLY then does mechanical drilling resume past the service position. Insulated PPE for cable risk. Where services run in the drill path, drilling abandoned and routed around.
    Acceptable whenHand tools (no impact) within 500mm of detected service position. Insulated tools EN 60900 if electrical risk. Service exposed, identified, marked before mechanical resumption. Re-route if service in drill path.
    StandardHSG47. EN 60900 / EN 60903.
    Common defectsSDS hammer drill used "carefully" within 500mm, vibrates and pierces conduitHand drill but no insulated PPE, operator shocked through tool bodyService exposed but mis-identified (mistaken for old abandoned cable, actually live)Re-route forgotten, drilling resumed straight through service
  5. 5.
    Depth and extent of penetration defined
    What to look forDrilling depth limited to the minimum needed for the fixing (e.g. M12 anchor needs 95mm embedment, depth stop set at 100mm not "drill until you feel through"). Drill depth stop fitted. Penetration through-drilling assessed for far-side hazards (live cable, person, occupied space below). Where through-drill, far side cleared and barriered.
    Acceptable whenDepth limited to design embedment + tolerance. Depth stop fitted. Through-drill: far side cleared, barriered, briefed. No through-drill into post-tension slab without specialist sign-off.
    StandardBS 8539:2012 Code of practice for selection and installation of post-installed anchors. Manufacturer fixing data.
    Common defectsDrilling "until it feels right", over-deep, penetrates conduit at the back of the wallThrough-drill assumed safe, operative on far side of wall struckDepth stop omitted, operator-judgement onlyDrill into PT slab cableFar-side void contains insulation, ignites from drill heat
  6. 6.
    Asbestos survey checked for hidden ACMs
    What to look forR&D survey reviewed for the specific drilling location, asbestos cement panels, AIB partitions, textured coatings, vinyl tile bedding, gaskets, cement-based pipe lagging. Drilling into ACMs even for fixings releases fibres. Where ACM present, work classified and HSE-licensed contractor engaged for licensed material; non-licensed work uses HSG210 controls.
    Acceptable whenR&D survey reviewed for the actual drill point. Sample taken if presumed ACM present. Licensed contractor for licensed-grade work. HSG210 controls for non-licensed (drill into AC, textured coating, vinyl): wet-drilling, H-class vacuum on tool, FFP3, wipe-down, double-bagged waste.
    StandardControl of Asbestos Regs 2012. HSG210 Asbestos essentials task sheets. HSG264 (survey).
    Common defectsDrill into textured ceiling coating without check, asbestos fibre releaseAIB drilled with dry drill, fibre cloudNo H-class vacuum, class M used, fibres exhaustedNo wipe-down post-drill, fibre residue on substrateSurvey reviewed for the room generally, not the specific drill point
  7. 7.
    Emergency procedure for service strike understood
    What to look forOperative briefed on actions if a service is struck: STOP, do not pull tool free (could expose live conductor), evacuate area, call emergency services, call site supervisor, call utility owner emergency line. For gas: evacuate, no ignition sources, ventilate. For electric: do not touch, call DNO. For water: shut off if known, call water company. Numbers posted on the permit.
    Acceptable whenStrike procedure briefed and signed. Emergency numbers on permit (gas 0800 111 999, electric DNO emergency, water company emergency). First aid response trained and available. Site evacuation procedure linked.
    StandardHSG47. HSWA 1974 s.2(2)(c) (information). Gas Safety (Management) Regulations 1996. ESQCR 2002.
    Common defectsOperative pulls drill out of struck cable, flash arc burn999 called but DNO not called, supply still live for 20 minutesNo emergency numbers on site, searched for at moment of incidentGas strike + ignition source not isolated, fire/explosionNo evacuation triggered, workers continue alongside leaking gas

Questions people ask

When is a breaking ground / penetration permit needed?

Drilling, coring, fixing into, or penetrating any surface where buried/hidden services may exist. A permit is the right control when the work is high risk, time-limited and depends on specific precautions being in place before it starts and being kept in place while it runs. It does not replace the RAMS; it sits on top of it for that shift. Guidance, not legal advice.

Who issues a permit to work?

An authorised person who is competent for that type of work and is not the one doing it. They walk the job, confirm each precaution, sign the permit, and hand it to the person in charge of the work, who accepts it by signature. Two names, two signatures, a start time and an expiry.

How long is a permit valid?

One shift, or a shorter stated period. If the conditions change, the permit is suspended, not stretched. A new day is a new permit, walked and signed again, because the site is not the same site it was yesterday.

What does critical mean on a precaution?

1 of the 7 precautions here are marked critical. If a critical precaution cannot be confirmed, the permit is not issued and the work does not start. The rest can be conditioned or noted; the critical ones cannot.

How is the permit closed out?

The person in charge hands it back when the work stops, the issuer checks the area is left safe, and both sign the close-out. For hot works that includes the fire watch period after the last spark. The closed permit is kept with the job file.

Issue it on a phone, close it out on a phone

The same 7 precautions with the guidance a tap away, issuer and acceptor signatures, start and expiry times, suspension, close-out and a branded PDF in the job file. 14 days free.

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