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From: Jarek Wityk
Sent: 03 November 2025 15:22
Subject: BS8519 awareness of the changes
Dear All
Following our workshop, and while working on other projects and considering the issue with the separation of the Central Battery Emergency Lighting system, I couldn’t stop thinking and analysing the BS 8519 requirements.
(I went through a similar exercise related to Fire Alarm Wiring, which triggered this email, so I thought I’d share the below with you.)
Let’s start with the scope of BS 8519:2020, which is key here
What BS 8519 does (and does not) cover.
BS 8519 is the UK code of practice for fire-resistant power/control cable systems that must remain operational in fire for life safety, firefighting, and other critical applications (e.g., smoke control fans, firefighters’ lifts, sprinkler/wet riser pumps). Crucially, BS 8519 explicitly excludes installations that are already covered by BS 5266‑1 (emergency lighting) and the BS 5839 series.
Implication: When dealing with centrally fed emergency lighting, the wiring rules do not originate from BS 8519; instead, they are derived from BS 5266‑- 1 (and the related EL system standards) via BS 7671.
Does central battery emergency lighting wiring fall into the requirements of BS 8519? – No, not for wiring method or containment, because BS 8519’s scope excludes installations covered by BS 5266‑1, the EL wiring/containment method is governed by BS 5266‑1 and BS 7671 (not BS 8519).
Does BS 7671 make this split explicit ?
Yes in BS 7671 Chapter 56:
- Emergency lighting systems “shall comply with the relevant parts of BS 5266 series and BS EN 1838.”
- Life‑safety & fire‑fighting applications (e.g., smoke control fans, fire‑fighting/evacuation lifts, sprinkler/wet‑riser pumps) must comply with BS 8519 for selection/installation of power/control cable systems.
- All safety services: circuits must be independent of other circuits (separation by routes/enclosures if needed).
- Wiring systems for safety services must be chosen/installed so circuit integrity is not impaired during a fire and should follow the relevant code of practice (i.e., BS 5266 for EL).
Implication: EL wiring follows BS 5266 (not BS 8519) but still the Chapter‑56 independence and fire‑survivability requirements in BS 7671 still apply.
But central battery EL wiring is “life safety”
Yes, it’s a safety service. That’s why BS 7671 Section 560 applies (independence, survivability), and why BS 7671 points EL to BS 5266/EN 1838 for the detailed design rules (levels, operation, circuiting philosophy, wiring approach).
What standards specify the wiring/containment method for the central battery EL?
- BS 5266‑1 (Code of practice for EL) system design, circuiting, wiring expectations and references to the system/product standards.
- BS EN 50171:2021 (Central safety power supply systems) — the product/system standard for the central source that feeds the EL. BS 5266‑1 directs you to it.
- BS EN/IEC 60598‑2‑22 (Luminaires for emergency lighting) and BS EN 1838 (lighting performance), product/performance standards referenced by BS 5266‑1 (latest editions are listed in the 2025 revision).
- BS 7671 Section 528 & 560, how to segregate EL circuits from others and how to select/erect wiring systems that survive fire. For mixed routes/enclosures, Regulation 528.1 sets the acceptable methods (e.g., separate compartments in trunking or a tray with a partition), and Section 560 adds the independence and fire-survivability requirements.
What this does mean:
BS 8519’s scope states it ‘does not give recommendations for those installations covered in … BS 5266‑1.’ Emergency lighting is covered by BS 5266‑1 and, per BS 7671, ‘Emergency lighting systems shall comply with the relevant parts of BS 5266 series and BS EN 1838.’ You do not apply BS 8519’s “dedicated cable support system” clause to EL wiring; BS 8519’s own scope excludes EL (BS 5266‑1).
Basically, what I am saying is that – at <annonymised>, the central battery emergency Lighting does not have to be installed on a dedicated cable support system, independent of other cable support systems
Hope this helps, let me know what you think.
Best,
Jarek Wityk
From: <anonymised>
Sent: 14 November 2025 14:02
Subject: RE: BS8519 awareness of the changes
Importance: High
Hi Jarek,
I love these debates. 😁 ok after reading your email below I would question the following which I feel we would be met with by client consultants and or MEP manager and or COW (clark or works)
BS8519 does state on page 8 section 1
However do you take the wording of “those installations” to be referring the physical installs???? As this BS is solely for supporting of life safety systems? BS8519 also states on page 18 section 7.3 which is referring to the supporting of all life safety systems.
Now if you refer to BS8519 survival times page 11 “emergency light related standard BS5266-1” emergency/escape or central battery lighting it states the minimum survival time is category 2 which is 60minutes.
So to recap in my mind, we have page 8 informing us BS8519 does not give recommendations to the listed BS’s, by page 18 it is informing us that life safety critical cables should be installed on dedicated cabling supports independent of all others and the supports would need to meet the survival times.
Now jumping over to BS5266-1 page 27 section 8.2.3
I believe what they mean at this point is that the rod/support must meet the requirements of BS8519 and be able to take the weight being applied.
BS5266-1 page 28 section 8.2.6
The above is clear, the cabling is to be separate from the wiring of other circuits.
BS5266-1 page 28 section 8.2.6 interesting bit
The above is interesting as the BS is now stating the emergency lighting cables/CBS circuits can now be installed on a common containment system as long as they are segregated.
So I think in my concussion if you go by 5266-1 you can have the cabling of the system on the same containment providing it has a divider, it could be supported by one common bracket, but would need to meet the requirements of BS8519 for weights and fire survival times. But then I still come back to BS8519 page 18 section 7.3 where it states “The life safety, fire-fighting and other critical system cables should be installed on a dedicated cable support system, independent of other cable support systems and designed to maintain its circuit integrity when exposed to fire conditions for a period of at least the survival time for the appropriate system” and the reason I come back to this BS/statement is because it is dedicated to life safety cabling supporting, I guess the question would be which BS is the hierarchy in documents??
Thoughts??
From: Jarek Wityk
Sent: 14 November 2025 16:51
Subject: RE: BS8519 awareness of the changes
Hi <anonymised>
Yes, can’t beat debating about the nuances of the requirements in the end, that’s what we’re fighting’ daily…
There is a bit of circular reference in BS5266-1 section 8.2.3, but as with any standard, there is a scope hierarchy, i.e.:
“This document applies to X, Y, Z and does not apply to A, B, C…”
That’s the gatekeeper. BS5266-1 is excluded from BS8519; the rest of the standard is not applicable to BS5266-1.
Recommendations in clause 7.3 and others only apply within the universe defined by the scope.
That means: all the detailed clauses (including 7.3) are not written to prescribe how EMG LTG installations (as defined by BS 5266-1) are to be wired or supported.
If you look at 7.3 in isolation:
“The life safety, fire-fighting and other critical system cables should be installed on a dedicated cable support system, independent of other cable support systems…”
If you read that literally and globally, you’d say:
- “Emergency lighting is a life safety system.”
- “Therefore 7.3 applies.”
- “Therefore, all EMG LTG cables must be on dedicated supports independent of others.”
However… that reading ignores the scope clause, which has already removed “installations covered by BS 5266-1” from the remit of BS 8519.
In standards, the rule of thumb is scope always constrains the later clauses.
The BS5266-1 page 28 section 8.2.6 does allow a common containment system with a solid partition – Yes, and yes, the BS5266-1 is deliberately referring to 8519:2020 for mechanical design method of supports/drop rods and the survival time categories, but it still does not mean central battery EMG LTG should be installed on a dedicated cable support system.
That’s my understanding anyway.
Best,
Jarek Wityk
