Name: Active Communication Company Limited
Telephone: 0333 900 0101

Ultimate Guide to Earthing & Equipotential Bonding for Reliable Data Cabling Installations

Why Earthing & Bonding Still Matters in 2025

At ACCL we spend our days surrounded by copper, fibre and ever‑hungrier IT loads. Yet even the smartest Cat6a link or 40 Gbit fibre backbone can be brought to its knees by a poorly planned earth path.

BS EN 50310:2016 + A1:2020 (usually shortened to BS EN 50310:2020) is the UK‑adopted European standard that explains how to design and verify a telecommunications bonding network (TBN) inside buildings. Think of it as the electrical glue that holds together structured cabling, power distribution, surge protection and lightning protection.

In this fresh, 2025‑ready rewrite we’ll walk you through what’s changed, the key design steps, and the common pitfalls we still find on site. We’ll link you to deeper resources along the way – so grab a brew and let’s dive in.

Quick refresher: Earthing creates a low‑impedance path to safely carry fault current to ground. Equipotential bonding connects conductive parts so they stay at (roughly) the same voltage under fault conditions. Together they protect people, equipment and network performance.

What’s new in BS EN 50310:2020?

The 2020 amendment aligns the standard with:

BS 7671:2018 + A2:2022 (18th Edition IET Wiring Regulations) – especially Chapter 44 on protection against transient overvoltages.
BS EN 50174‑2:2018 – which tightened rules on cable separation from LV power circuits and introduced new containment materials.
BS EN 62305‑4:2019 – lightning protection and surge protective device (SPD) coordination.

Key Technical Updates

Area	Pre‑2020 guidance	BS EN 50310:2020 update
Telecommunications Main Earthing Terminal (TMGB)	6 mm² minimum conductor	16 mm² Cu or equivalent; larger for >200 kA lighting risk
Earth Bonding Network (EBN) mesh size	10 × 10 m guideline	Mesh ≤5 × 5 m for high‑speed data (>10 Gbps)
Supplementary Bonding Networks	Optional	Mandatory in floor VoIP & Wi‑Fi dense offices
Measurement & verification	Visual check	Impedance test ≤0.2 Ω at every bond
Documentation	Single line diagram	Full BIM‑compatible model + maintenance schedule

0333 900 0101 sales@network-data-cabling.co.uk Contact us

      EXCELLENT  
   Based on 66 reviews 
    
 
 
 
   
 
 
       Posted on Google  
   
   Andrew Matthews 
 
 
 
 Trustindex verifies that the original source of the review is Google. We commissioned a Wi-Fi survey and installation of new fibre and Cat6 cabling to support a new Wi-Fi installation from Accl in July and August of 2026. ACCL were superb from start to finish. We cannot fault the quality of the work and we received great advice on our project. Very satisfied customer!
  
 
      Posted on Google  
   
   Brigt Valland 
 
 
 
 Trustindex verifies that the original source of the review is Google. Very professional company, good at understanding our need and efficient delivery of new building network- and WIFI infrastructure. An extra star for making it easy for me to "remote" organize this from Norway.
  
 
      Posted on Google  
   
   Siobhan Codd 
 
 
 
 Trustindex verifies that the original source of the review is Google. We used ACCL for a full WiFi and network install at our Old Street office and are very pleased with the result. They supplied and installed seven Ubiquiti WiFi access points, a UniFi Dream Machine, a 24 port Layer 3 Ubiquiti switch, and ran new Cat6A Leviton cabling with two ports to every AP. The whole job was neat, well planned and done to a very high standard. The coverage across the office is excellent and it looks pretty cool too! Would happily recommend them to anyone needing cabling or network infrastructure done properly.
  
 
      Posted on Google  
   
   Mark Cooper 
 
 
 
 Trustindex verifies that the original source of the review is Google. An excellent service from start to finish!
The ACCL team installed our new network cabling, the foundation in readiness for supplying and installing a new IP CCTV camera system, professionally and efficiently. They were punctual, knowledgeable, and took the time to ensure everything was installed neatly and working perfectly. Their attention to detail and customer service were outstanding. I very much appreciate the initial project management and upfront planning, which combined to secure a successful delivery. I would highly recommend them to anyone looking for reliable network cabling or CCTV installation. Thank you for a fantastic job.
  
 
      Posted on Google  
   
   Mohammed Alhashimi 
 
 
 
 Trustindex verifies that the original source of the review is Google. I would like to express my sincere appreciation to Wayne and his team for the excellent work they carried out. From start to finish, they were professional, reliable, efficient, and clearly took great pride in delivering a high standard of service.

They were professional, efficient, and paid great attention to detail, ensuring everything was neat, clearly labelled, well organised, and completed to a very high standard. The end result was clean, structured, and exactly what we needed.

Wayne and his team were reliable, courteous, and clearly committed to doing the job properly rather than simply getting it done. I would highly recommend them to anyone looking for professional cabling work and a team that genuinely takes pride in the quality of their finish.
  
 
      Posted on Google  
   
   Laurence Rutter 
 
 
 
 Trustindex verifies that the original source of the review is Google. So easy to deal with! Great price and great guys! Did exactly what they agreed, on time and in budget. Would thoroughly recommend them to anyone.
  
 
      Posted on Google  
   
   AlonMel Music 
 
 
 
 Trustindex verifies that the original source of the review is Google. Wayne and team did an excellent job tidying our office data cabinet over the weekend. Professional, clean work—they went above and beyond with cable management and even relocated the router. Communication was impeccable throughout. Highly recommend.
  
 
      Posted on Google  
   
   Amritpal Singh 
 
 
 
 Trustindex verifies that the original source of the review is Google. "Outstanding service from ACCL. They did an incredible job with our networking and data cabling. The setup is neat, professional, and works perfectly. Extremely knowledgeable and easy to work with. I’ll definitely be using them for all our future IT needs!"

Huge Shout to Wayne Connors and David Little for managing this.
  
 
      Posted on Google  
   
   Andy Dawson 
 
 
 
 Trustindex verifies that the original source of the review is Google. We've worked with Wayne, David and the ACCL team for a number of years on projects throughout London. One of very few suppliers that we never have to question their proposal on detail or price, everything is clear, transparent and fair. Projects are always completed on time and there are never any costly surprises which we had previously experienced from other suppliers. They all have a vast knowledge on anything fibre optic cabling, copper cabling or wifi. ACCL is now the only data cabling company in our phone book. Highly recommended.
  
 
      Posted on Google  
   
   Indrajit Shah 
 
 
 
 Trustindex verifies that the original source of the review is Google. Great service and communication. Will definitely be contacting Wayne and ACCL for future projects.
  
 
  
  
 
     Verified by Trustindex  Trustindex verified badge is the Universal Symbol of Trust. Only the greatest companies can get the verified badge who has a review score above 4.5, based on customer reviews over the past 12 months. Read more

The Three‑Layer Bonding Strategy

BS EN 50310 divides bonding into nested networks. We like to explain it with the image of an onion:

BBN – Building Bonding Network
Your incoming LV supply earthing conductor, structural steel and lightning protection system. Typically installed by your electrical contractor during shell‑and‑core.
EBN – Equipotential Bonding Network
Mesh of copper tapes, trays or earth bars that links plant rooms, risers and key containment routes. ACCL normally bonds containment every 20 m horizontally and each floor vertically.
SBN – Supplementary Bonding Network
Local equipotential bonding inside ICT rooms, racks and even under raised floors.

Tip: Use pre‑tinned 25 × 3 mm copper tape for riser bonding – it doubles as structural lightning down‑lead and saves space.

Designing an Earthing & Bonding Scheme – Step‑by‑Step

1. Gather the facts

Lightning risk assessment per BS EN 62305‑2.
Load schedule – servers, PoE LED lighting, CCTV, Wi‑Fi 6E APs. Higher harmonic currents demand lower impedance bonds.
Cable architecture – Are you running multi‑tenant fibre backbones? (See our guide on data cabling for multi‑tenant office buildings).

2. Choose your reference earth bar locations

Locate the Telecommunications Main Earthing Terminal (TMGB) as close as practical to the main incoming data cabling plant – usually the Main Equipment Room (MER). ACCL specifies stainless steel earth bars pre‑drilled for M10 lugs and labelled for future adds.

3. Size conductors correctly

16 mm² stranded Cu is the new minimum, but we often upsize to 25 mm² where racks exceed 10 kA fault level or to maintain equal length multiples.

4. Minimise loop impedance

Route bonding conductors in parallel with data containment – never bundled with register power cables (to stay aligned with BS EN 50174‑2 separation). Keep bends gradual; every 90° corner adds inductive reactance.

5. Plan for SPDs and MCB coordination

Modern PoE switches are vulnerable to transient over‑voltage. Coordinate Type 2 SPDs at each floor‑level distribution board and Type 3 devices at rack PDU level. See our article on cabling fire safety and over‑current protection for deeper guidance.

6. Document & test

Use BIM‑compatible single‑line diagrams exported in IFC.
Perform continuity testing – target ≤0.2 Ω between any exposed‑conductive‑part and the TMGB.
Keep results with O&M manual and schedule annual retesting – your facilities team can book this as part of an ACCL data‑cabling audit.

0333 900 0101 sales@network-data-cabling.co.uk Contact us

      EXCELLENT  
   Based on 66 reviews 
    
 
 
 
   
 
 
       Posted on Google  
   
   Andrew Matthews 
 
 
 
 Trustindex verifies that the original source of the review is Google. We commissioned a Wi-Fi survey and installation of new fibre and Cat6 cabling to support a new Wi-Fi installation from Accl in July and August of 2026. ACCL were superb from start to finish. We cannot fault the quality of the work and we received great advice on our project. Very satisfied customer!
  
 
      Posted on Google  
   
   Brigt Valland 
 
 
 
 Trustindex verifies that the original source of the review is Google. Very professional company, good at understanding our need and efficient delivery of new building network- and WIFI infrastructure. An extra star for making it easy for me to "remote" organize this from Norway.
  
 
      Posted on Google  
   
   Siobhan Codd 
 
 
 
 Trustindex verifies that the original source of the review is Google. We used ACCL for a full WiFi and network install at our Old Street office and are very pleased with the result. They supplied and installed seven Ubiquiti WiFi access points, a UniFi Dream Machine, a 24 port Layer 3 Ubiquiti switch, and ran new Cat6A Leviton cabling with two ports to every AP. The whole job was neat, well planned and done to a very high standard. The coverage across the office is excellent and it looks pretty cool too! Would happily recommend them to anyone needing cabling or network infrastructure done properly.
  
 
      Posted on Google  
   
   Mark Cooper 
 
 
 
 Trustindex verifies that the original source of the review is Google. An excellent service from start to finish!
The ACCL team installed our new network cabling, the foundation in readiness for supplying and installing a new IP CCTV camera system, professionally and efficiently. They were punctual, knowledgeable, and took the time to ensure everything was installed neatly and working perfectly. Their attention to detail and customer service were outstanding. I very much appreciate the initial project management and upfront planning, which combined to secure a successful delivery. I would highly recommend them to anyone looking for reliable network cabling or CCTV installation. Thank you for a fantastic job.
  
 
      Posted on Google  
   
   Mohammed Alhashimi 
 
 
 
 Trustindex verifies that the original source of the review is Google. I would like to express my sincere appreciation to Wayne and his team for the excellent work they carried out. From start to finish, they were professional, reliable, efficient, and clearly took great pride in delivering a high standard of service.

They were professional, efficient, and paid great attention to detail, ensuring everything was neat, clearly labelled, well organised, and completed to a very high standard. The end result was clean, structured, and exactly what we needed.

Wayne and his team were reliable, courteous, and clearly committed to doing the job properly rather than simply getting it done. I would highly recommend them to anyone looking for professional cabling work and a team that genuinely takes pride in the quality of their finish.
  
 
      Posted on Google  
   
   Laurence Rutter 
 
 
 
 Trustindex verifies that the original source of the review is Google. So easy to deal with! Great price and great guys! Did exactly what they agreed, on time and in budget. Would thoroughly recommend them to anyone.
  
 
      Posted on Google  
   
   AlonMel Music 
 
 
 
 Trustindex verifies that the original source of the review is Google. Wayne and team did an excellent job tidying our office data cabinet over the weekend. Professional, clean work—they went above and beyond with cable management and even relocated the router. Communication was impeccable throughout. Highly recommend.
  
 
      Posted on Google  
   
   Amritpal Singh 
 
 
 
 Trustindex verifies that the original source of the review is Google. "Outstanding service from ACCL. They did an incredible job with our networking and data cabling. The setup is neat, professional, and works perfectly. Extremely knowledgeable and easy to work with. I’ll definitely be using them for all our future IT needs!"

Huge Shout to Wayne Connors and David Little for managing this.
  
 
      Posted on Google  
   
   Andy Dawson 
 
 
 
 Trustindex verifies that the original source of the review is Google. We've worked with Wayne, David and the ACCL team for a number of years on projects throughout London. One of very few suppliers that we never have to question their proposal on detail or price, everything is clear, transparent and fair. Projects are always completed on time and there are never any costly surprises which we had previously experienced from other suppliers. They all have a vast knowledge on anything fibre optic cabling, copper cabling or wifi. ACCL is now the only data cabling company in our phone book. Highly recommended.
  
 
      Posted on Google  
   
   Indrajit Shah 
 
 
 
 Trustindex verifies that the original source of the review is Google. Great service and communication. Will definitely be contacting Wayne and ACCL for future projects.
  
 
  
  
 
     Verified by Trustindex  Trustindex verified badge is the Universal Symbol of Trust. Only the greatest companies can get the verified badge who has a review score above 4.5, based on customer reviews over the past 12 months. Read more

Common Site Issues & How We Solve Them

Isolated racks in legacy buildings

Historic estates often have patch cabinets in closets with no local earth. We install sub‑earth bars and bond back to the EBN via spare steel conduit – quick win, minimal disruption. (See tips for heritage sites in our post on network cabling upgrades in historic buildings).

Poor segregation from power

Running Cat6a right next to 400 V armoured cable invites EMI. BS EN 50174‑2 calls for 200 mm air gap or metallic divider. We like basket tray with a snap‑on copper lid – gives both screening and bonding.

Forgotten PoE lighting drivers

PoE luminaires are usually Class 2, but the metallic housings still need bonding if they’re part of a suspended ceiling grid. We fit bonding jumpers every 3rd tile run.

Painted steelwork

A fresh coat of intumescent paint looks great but kills conductivity. Our engineers file small coupon‑size patches and apply conductive grease before bolting earth lugs. We then spray clear lacquer for corrosion resistance.

Missing documentation

If you can’t prove the earth path, insurers may refuse downtime claims. ACCL offers digital twin asset tagging – scan a QR code on the earth bar, pull test certs instantly. Talk to our structured cabling team to learn more.

Earthing & Bonding Checklist

☐ Lightning risk assessment complete
☐ TMGB located <5 m of MER
☐ BBN, EBN, SBN routes modelled in BIM
☐ All data containment bonded every 20 m & each floor
☐ SPDs coordinated (Type 1 at service entry, Type 2 at DBs, Type 3 at racks)
☐ Continuity tested ≤0.2 Ω end‑to‑end
☐ O&M manual + maintenance plan issued

Need help ticking every box? Contact ACCL – our NICEIC‑approved engineers are ready to assist.

Future Trends – Mesh Bonding meets Smart Buildings

Smart building platforms, digital twins and IoT sensors are turning every luminaire, HVAC damper and door into a network node. That means more PoE, more edge switches, and more paths for fault currents. Expect the next revision of BS EN 50310 to address:

Higher‑power PoE (IEEE 802.3bt) – up to 90 W per port influencing conductor sizing.
DC microgrids – common earth reference between AC and 48 V DC busbars.
Active monitoring – continuous impedance sensing via inline probes and cloud dashboards.

Staying proactive with a robust bonding design today will make tomorrow’s retrofits painless.

Wrapping Up

Earthing and equipotential bonding may not be as glamorous as 800 Gig Ethernet optics, but without it your digital infrastructure is literally built on shaky ground. BS EN 50310:2020 gives a clear, modern framework. Combine it with the 18th Edition wiring regs, a dash of practical field know‑how and reliable test data, and you’ve set the foundation for decades of resilient uptime.

If you’d like us to review your current installation, perform impedance testing or design a bonding network from scratch, reach out to ACCL today.

Active Communication Company Ltd, trading as ACCL · Commercial data cabling and network infrastructure specialists

Ultimate Guide to Earthing & Equipotential Bonding for Reliable Data Cabling Installations

Why Earthing & Bonding Still Matters in 2025

What’s new in BS EN 50310:2020?

Key Technical Updates

Area

Pre‑2020 guidance

BS EN 50310:2020 update

Telecommunications Main Earthing Terminal (TMGB)

6 mm² minimum conductor

16 mm² Cu or equivalent; larger for >200 kA lighting risk

Earth Bonding Network (EBN) mesh size

10 × 10 m guideline

Mesh ≤5 × 5 m for high‑speed data (>10 Gbps)

Supplementary Bonding Networks

Optional

Mandatory in floor VoIP & Wi‑Fi dense offices

Measurement & verification

Visual check

Impedance test ≤0.2 Ω at every bond

Documentation

Single line diagram

Full BIM‑compatible model + maintenance schedule