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Metering Maintenance

Electricity Sub-Meter Maintenance Checklist

Keep tenant recharge and energy data defensible — reading reconciliation, CT-ratio and pulse-output verification, MID-compliance checks, and BMS data integrity.

What is an electricity sub-meter maintenance checklist?

A electricity sub-meter maintenance checklist is a structured list of the 10 preventive maintenance tasks — covering visual, functional and record-keeping checks — that keep an electricity sub-meter running safely and reliably. It groups routine checks by frequency, from daily inspections to annual servicing, so FM teams and building engineers can plan and evidence preventive maintenance.

Core electricity sub-meter checks

  • Inspect terminations, CT leads, and the meter for security and damage
  • Reconcile a manual meter reading against the BMS/aMR logged value
  • Confirm MID compliance where the meter is used for tenant billing

What is an electricity sub-meter?

An electricity sub-meter measures consumption for a tenant, floor, or item of plant downstream of the main incoming meter, supporting tenant recharge, energy management, and ESG reporting. Sub-meters use current transformers (CTs) on larger circuits and feed pulse or Modbus/BACnet data to the BMS or aMR system. Where used for billing a tenant, meters generally need to be MID (Measuring Instruments Directive) compliant. Accuracy depends heavily on the CT ratio being set correctly and the CTs being installed the right way round — a common and costly error. Maintenance verifies readings, CT configuration, and data integrity.

Typical Electricity Sub-Meter maintenance checklist

A practical starting point for planned preventive maintenance. Always refer to the manufacturer's O&M manual and site-specific requirements.

Visual Checks

  • Inspect terminations, CT leads, and the meter for security and damage
  • Confirm meter mapping matches the metering schedule and distribution boards

Functional Checks

  • Reconcile a manual meter reading against the BMS/aMR logged value
  • Confirm the configured CT ratio matches the installed current transformers
  • Check CTs are installed the correct way round and on the right phases
  • Verify the pulse/Modbus/BACnet output reports correct, incrementing data
  • Check the meter reads near zero when the metered load is off
  • Reconcile sub-meter totals against the parent/incoming meter

Record Keeping

  • Confirm MID compliance where the meter is used for tenant billing
  • Record readings, CT settings, and reconciliation in the metering log

Typical maintenance frequency

Suggested intervals for electricity sub-meter maintenance. Actual frequencies should follow manufacturer guidance and site-specific risk assessments.

Monthly

  • Reconcile manual vs logged reading
  • Reconcile sub-meters vs parent
  • Review consumption trend

Annually

  • Verify CT ratios and orientation
  • Confirm MID status for billing meters
  • Check comms/pulse integrity
  • Audit meter mapping

Common faults and issues

Issues to be aware of when maintaining electricity sub-meter equipment.

CT ratio in the meter not matching the installed CTs, scaling all readings wrong
CTs fitted the wrong way round or on the wrong phase, giving low or negative readings
Non-MID meter used for tenant billing, creating a recharge compliance problem
Comms dropout leaving gaps in the energy data feeding reports
Sub-meter totals not reconciling with the incoming meter, hiding unmetered loads
Meter mapping errors so consumption is attributed to the wrong tenant or plant

Safety and compliance notes

Key safety considerations for electricity sub-meter maintenance. This is general guidance only — always follow OEM instructions, statutory requirements, and your organisation's safe systems of work.

Never open-circuit a live CT secondary — dangerous voltages can result; short or isolate correctly
Only qualified electrical persons should work on CTs, terminations, and metering panels
Confirm MID compliance before relying on a meter for tenant billing
Keep meter mapping accurate so recharge is defensible in a dispute
Isolate safely before any intrusive work on metering circuits
How PM Assist helps

Managing Electricity Sub-Meter documentation with PM Assist

PM Assist helps FM and building operations teams search their O&M manuals and building drawings in seconds. Upload your electricity sub-meter documentation and ask questions like “What is the CT ratio for this meter?” or “Which board or tenant does it serve?” — and get source-cited answers instantly.

See PM Assist answer questions about a real electricity sub-meter manual — try the live demo, no signup needed.

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Frequently asked questions

Manage your building documentation with AI

PM Assist gives FM teams instant access to O&M manuals, drawings, and maintenance knowledge — all searchable with AI.

  • Upload and organise building documentation
  • AI-powered search across all your manuals
  • Source-cited answers for maintenance queries
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