Fire safety cables for data centres: understanding B2ca, Cca, Dca ratings, and EN 50575 tests

Q: What is data centre CPR cable classification?

CPR cable classification is the fire-performance rating assigned to cables under the EU Construction Products Regulation and tested to EN 50575. For a data centre, the relevant classes are B2ca, Cca and Dca, which grade how a cable behaves in a fire: how fast flame spreads, how much heat and smoke it releases, and whether it drips flaming particles.

Q: What is a data centre B2ca cable?

A B2ca cable is the highest LSZH fire-performance class available for power and data cabling. In a data centre, B2ca cables deliver the slowest fire growth (FIGRA ≤150 W/s), the lowest heat release (THR ≤15 MJ) and minimal smoke, making them the preferred choice for high-density server rooms and critical infrastructure.

Q: What is the difference between a Cca cable and a B2ca cable?

Both are LSZH classes tested under EN 50575, but a Cca cable sits one tier below B2ca. Cca allows a higher FIGRA (≤300 W/s) and more total heat release (≤30 MJ), so fire spreads faster and hotter than with B2ca. Cca still outperforms Dca cable by a wide margin, but B2ca remains the top-tier option for the most critical data centre areas.

Q: Are all LSZH cables for data centres equally fire safe?

No. "LSZH" only confirms that a cable is halogen-free and won't release toxic acid gas when it burns — it says nothing about how fast the fire spreads, how much heat it releases, or how much smoke it produces. B2ca, Cca and Dca are all LSZH, yet their fire performance under EN 50399 differs significantly, so the CPR class matters as much as the LSZH label.

Q: What does EN 50575 require for cables installed in data centres?

EN 50575 is the harmonised standard behind the EU Construction Products Regulation. It defines the tests — including EN 60332-1-2 (flame propagation), EN 50399 (the single burning item test for FIGRA, heat and smoke release), EN 61034-2 (smoke density) and EN 60754-2 (halogen acid content) — used to assign a cable its Euroclass (B2ca, Cca, Dca, etc.) for construction works, including data centres.

Q: What is a fire safety cable and how does it differ from an LSZH cable?

An LSZH (B2ca/Cca) cable is designed to slow fire growth, limit smoke and avoid toxic halogen gases, but it is not designed to keep working once it is on fire. A fire safety cable is built to maintain electrical circuit continuity during a fire, so critical systems such as alarms, emergency lighting or fire pumps keep operating for a defined period even as the cable burns.

Q: What is TOXFREE cable?

TOXFREE® is our range of LSZH cables engineered specifically for data centre and critical infrastructure applications. Every TOXFREE® cable meets B2ca-s1a,d1,a1 or Cca-s1,d1,a1 ratings — we do not manufacture or distribute Dca cable — so every unit combines low smoke, low toxicity and controlled fire growth.

Q: Why do data centre operators choose low smoke zero halogen cables over standard PVC cables?

Standard PVC cables release dense black smoke and corrosive halogen acid gases when they burn. Low smoke zero halogen cables avoid both problems: they preserve visibility for evacuation and for fire crews, and they don't generate the hydrochloric acid gas that reacts with sprinkler water to corrode servers, racks and equipment rooms far from the source of the fire.

Q: How does cable fire safety affect data centre uptime and downtime costs?

Cable fire safety is directly tied to business continuity. A cable that slows FIGRA and limits heat release buys suppression systems and staff more time to contain an incident before it spreads through cable trays and racks. Choosing higher-tier B2ca or Cca cable, or fire resistant cable where continuity is critical, reduces the risk of the extended downtime, equipment loss and corrosion damage that follow a major fire event.

Q: What makes Top Cable a top tier cable supplier for data centres?

We exclusively manufacture and distribute B2ca and Cca LSZH cable — never Dca — for data centre applications. Our TOXFREE® range, including the TOXFREE® LSZH N2XH Flex, is built to the strictest FIGRA, THR, smoke and halogen-acid limits under EN 50575, and is complemented by a fire resistant cable range for circuits that must stay operational during a fire.

LSZH does not equal fire safety cables. B2_ca, C_ca and D_ca cables are all halogen-free, but their fire performance under EN 50399 test varies significantly

How can data centre operators mitigate fire risk with cable selection? In a Data Centre, every second during a fire is critical. The cables installed throughout the facility can either help contain a fire or contribute to its spread. Understanding the differences between LSZH (Low Smoke Zero Halogen) B2_ca, C_ca, and D_ca cables can minimize this risk, protecting people, safeguarding infrastructure, and reducing potentially enormous downtime costs.

The “LSZH” designation confirms that a cable will not release toxic halogen gases, when burning. However, it does not indicate how quickly fire spreads (FIGRA), how much heat the cable contributes (THR), or how much smoke is produced (TSP). These measurable performance criteria distinguish minimum compliance from high-performance fire safety cables.

INDEX

The CPR fire classification hierarchy

EU Construction Products Regulation (CPR) and EN 50575 norm rank cables based on strict fire testing standards:

B2_ca (highest LSZH tier)
C_ca (mid-tier LSZH)
D_ca (minimum LSZH tier)

Key cable fire performance metrics

CPR classifications are based on rigorous fire tests:

EN 6033-2-1-2: vertical flame propagation test. This test verifies individual cables do not act as vertical “wicks” that carry fire through a building. All B2ca , Cca , Dca, must pass this baseline requirement.

EN 50399: the single burning item (SBI) test. This is the primary test that separates B2_ca and C_ca cables from D_ca cables. Cables are bundled to similate real installations and measure:

Flame spread (how far flame spreads upward)

FIGRA (Fire Growth Rate Index) measures how fast a fire develops. A lower FIGRA significantly slows fire development, this can mean the difference between a contained incident and a facility-wide disaster in environments where cable densities are high.

B2_ca ≤ 150 W/s
C_ca ≤ 300 W/s
D_ca ≤ 1300 W/s

THR1200s (total heat release in 20 minutes). Lower heat release protects people and equipment from severe damage.

B2_ca ≤ 15 MJ
C_ca ≤30MJ
D_ca ≤ 70 MJ

Smoke production (s1, s2, s3 ratings) Total Smoke Production (TSP1200s) determines visibility during evacuation. Heavy smoke reduces visibility, creating life-threatening conditions in critical places like data centres.

B2_ca-s1a and C_ca-s1 ≤ 50 m². (maintain visibility at 10+ metres during fire conditions)
D_ca-s3 > 400 m² (reduce visibility to under 3 metres during fire conditions)

Flaming droplets evolution (d0, d1, d2 ratings). No flaming droplets/particles lasting over 10 seconds (d0/d1) prevents the ignition of additional fires and stops fire spread. Flaming droplets/particles detaching from burning materials can ignite secondary fires, causing rapid fire spread throughout the building.

d0: No flaming droplets/particles within 1200 seconds
d1: No flaming droplets/particles persisting longer than 10 seconds within 1200 seconds
d2: No performance declared or does not meet d0/d1 criteria

EN 61034-2: smoke density test. This test measures optical smoke density when cables burn in a closed chamber:

**S1 rating (B2_ca, C_ca s1): **Light transmittance ≥ 60% (you can see through the smoke)
S2 rating (C_ca s2): Light transmittance ≥ 60% but < s1 performance
S3 rating (D_ca s3): Light transmittance < 60% (dense smoke)

EN 60754-2: Halogen acid content test (the “a” designation). This is what separates B2ca-s1a from Cca-s1 cables.

“a” designation (acidity) requires ≤ 0.5% halogen acid gas content
Non “a” cables can release up to 10x more corrosive gases

When cables burn, they release hydrochloric acid gas that reacts with sprinkler water to form indoor acid rain, corroding servers and equipment rooms. B2ca-s1a are halogen free, stopping this effect.

Why B2ca and Cca cables deliver superior fire protection

Within the LSZH category, B2ca and Cca specifications dramatically outperform Dca across five key parameters:

Slower fire growth
Lower heat release
Less smoke production
Less flaming droplets
Reduced corrosive emissions

These differences can determine whether a fire in a Data Centre remains contained or escalates into a major incident.

Why CPR classification matters in Data Centres

The LSZH label alone does not guarantee equivalent fire performance. Specifying CPR classification as part of a data centre’s passive fire protection strategy allows engineers and facility managers to align fire safety performance and operational risk and regulatory requirements.

The TOXFREE® LSZH N2XH Flex range, manufactured by Top Cable, is designed to meet B2_ca and C_ca fire safety cables classification requirements. For applications requiring electrical circuit continuity during a fire, Top Cable also offer fire safety cables designed to keep critical systems operational when it matters most.

TOXFREE®: The Data Centre-Grade LSZH Cable Solution

Don’t let the “LSZH” label create a false sense of equivalence. At Top Cable, we don’t compromise on fire safety. That’s why we exclusively manufacture and distribute LSZH cables with B2ca s1a,d1,a1 and Cca s1,d1,a1 ratings—never Dca.

Our TOXFREE® product range, including the TOXFREE® LSZH N2XH Flex, delivers the superior fire performance metrics that Data Centres demand: Every TOXFREE® cable delivers across all four parameters that matter most to data centre fire safety:

Controlled fire growth — FIGRA ≤150 W/s, giving your suppression systems and teams maximum response time
Minimal heat release — THR ≤15 MJ, limiting thermal damage to equipment inside and beyond the fire zone
Low smoke generation — TSP ≤50 m² with ≥80% light transmittance, preserving evacuation visibility and limiting smoke contamination of sensitive equipment
Zero corrosive gases — halogen acid content below 0.5%, eliminating the acid condensation risk that destroys equipment far beyond the fire origin point

For applications requiring electrical circuit continuity during a fire, we also offer fire safety cables designed to keep critical systems operational when it matters most.

When you specify Top Cable, you’re investing in the highest tier of fire safety engineering available in Europe.

Protect your infrastructure. Protect your people. Protect your business continuity. Contact Top Cable today to discuss B2ca and Cca LSZH cable solutions for your critical infrastructure project.

Choose Fire Safety cables. Choose Top Cable.

Frequently Asked Questions (FAQ)

What is data centre CPR cable classification?

CPR cable classification is the fire-performance rating assigned to cables under the EU Construction Products Regulation and tested to EN 50575. For a data centre, the relevant classes are B2_ca, C_ca and D_ca, which grade how a cable behaves in a fire: how fast flame spreads, how much heat and smoke it releases, and whether it drips flaming particles.

What is a data centre B2_cacable?

A B2_ca cable is the highest LSZH fire-performance class available for power and data cabling. In a data centre, B2_ca cables deliver the slowest fire growth (FIGRA ≤150 W/s), the lowest heat release (THR ≤15 MJ) and minimal smoke, making them the preferred choice for high-density server rooms and critical infrastructure.

What is the difference between a C_ca cable and a B2_ca cable?

Both are LSZH classes tested under EN 50575, but a C_ca cable sits one tier below B2_ca. C_ca allows a higher FIGRA (≤300 W/s) and more total heat release (≤30 MJ), so fire spreads faster and hotter than with B2_ca. C_ca still outperforms D_ca cable by a wide margin, but B2_ca remains the top-tier option for the most critical data centre areas.

Are all LSZH cables for data centres equally fire safe?

No. “LSZH” only confirms that a cable is halogen-free and won’t release toxic acid gas when it burns — it says nothing about how fast the fire spreads, how much heat it releases, or how much smoke it produces. B2_ca, C_ca and D_ca are all LSZH, yet their fire performance under EN 50399 differs significantly, so the CPR class matters as much as the LSZH label.

What does EN 50575 require for cables installed in data centres?

EN 50575 is the harmonised standard behind the EU Construction Products Regulation. It defines the tests — including EN 60332-1-2 (flame propagation), EN 50399 (the single burning item test for FIGRA, heat and smoke release), EN 61034-2 (smoke density) and EN 60754-2 (halogen acid content) — used to assign a cable its Euroclass (B2_ca, C_ca, D_ca, etc.) for construction works, including data centres.

What is a fire safety cable and how does it differ from an LSZH cable?

An LSZH (B2_ca/C_ca) cable is designed to slow fire growth, limit smoke and avoid toxic halogen gases, but it is not designed to keep working once it is on fire. A fire safety cable is built to maintain electrical circuit continuity during a fire, so critical systems such as alarms, emergency lighting or fire pumps keep operating for a defined period even as the cable burns.

What is TOXFREE cable?

TOXFREE® is our range of LSZH cables engineered specifically for data centre and critical infrastructure applications. Every TOXFREE® cable meets B2_ca-s1a,d1,a1 or C_ca-s1,d1,a1 ratings — we do not manufacture or distribute D_ca cable — so every unit combines low smoke, low toxicity and controlled fire growth.

Why do data centre operators choose low smoke zero halogen cables over standard PVC cables?

Standard PVC cables release dense black smoke and corrosive halogen acid gases when they burn. Low smoke zero halogen cables avoid both problems: they preserve visibility for evacuation and for fire crews, and they don’t generate the hydrochloric acid gas that reacts with sprinkler water to corrode servers, racks and equipment rooms far from the source of the fire.

How does cable fire safety affect data centre uptime and downtime costs?

Cable fire safety is directly tied to business continuity. A cable that slows FIGRA and limits heat release buys suppression systems and staff more time to contain an incident before it spreads through cable trays and racks. Choosing higher-tier B2_ca or C_ca cable, or fire resistant cable where continuity is critical, reduces the risk of the extended downtime, equipment loss and corrosion damage that follow a major fire event.

What makes Top Cable a top tier cable supplier for data centres?

We exclusively manufacture and distribute B2_ca and C_ca LSZH cable — never Dca — for data centre applications. Our TOXFREE® range, including the TOXFREE® LSZH N2XH Flex, is built to the strictest FIGRA, THR, smoke and halogen-acid limits under EN 50575, and is complemented by a fire resistant cable range for circuits that must stay operational during a fire.