There was a question I saw a little while ago on one of the engineering groups, when is the protection of electrical rooms ⚡️ with extinguishers only 🧯 and when is an automatic system used 🤔?

The answer will be summarized in clear points and with reference from the codes ✍️:

01- For the answer, several sources will be used, namely 👀
NFPA 13HB – NFPA 101 – NFPA 70 – NFPA 20 – FM GLOBAL

02- First, as stated in NFPA 13HB Chapter 8 – Electricity rooms must be protected ⚡️ with sprinklers 💦 unless:
A – The room was protected by two-hour resistance walls ⏰.
B – It is used only for electrical panels and is not used for any other purpose or storage.
C- The electrical devices or equipment shall be of the dry type.
It will certainly tell our minds how to use a water system with electrical rooms, which is a conductor of current – it is actually used to protect rooms, but the necessary precautions must be taken to prevent direct contact between water and exposed electrical parts, or the use of a preaction system – and by analogy, as stated in NFPA 20 that the degree of insulation be For electrical panels not less than IP31 – any way to completely disconnect the electrical current before the water exits.

03- As stated in NFPA 101 Chapter 9, alternative spraying systems such as CO2, clean agent or mist can be used in case of fear of the effect of water on the contents of the room.

04- As stated in Annex G – NFPA 70, the SCADA (control) rooms are protected through a Preaction sprinkler system of a type Double interlock or an alternative automatic protection system.

05- As stated in NFPA 70, the electrical rooms responsible for the power of the buildings are protected through an automatic system, whether sprinklers or gas, or they are protected by two-hour resistance rooms ⏰.

06- As stated in NFPA 70, transformer rooms are to be protected ⚡️ according to their type, whether they are dry or of the wet type (Oil type) as follows:
A- Dry type transformers:
1- Up to 112.5 KVA, no automatic extinguishing system is used (manual extinguishers are used) and only 30 cm is left between them and any flammable material.
2- The largest 112.5 KVA is protected by 1 hour resistance walls.
3- More than 35 kva, the room is protected by 3 hour or 1 hour resistance walls with an automatic system.
B- Wet-type transformers (Oil type) are protected by resistive walls for 3 hours ⏰ or one hour ⏰ with an automatic system.

07- As stated in FM global, there is a table of suitable systems for various applications, including electrical rooms and communication rooms, which are protected by gas systems.

08- As for transformers, they are divided according to the type of transformer if it is dry or wet, as well as if it is approved first, as well as the volume of oil in it if it is of the wet type as follows:
A – If it is of the dry type, do not use an automatic system.
B – If the wet type, transformer and oil are approved, an automatic system is not used.
C- If it is of the wet type and the transformer is not approved, but the oil is approved, clock-resistant walls should work or an automatic system should be made.
D- If it is of the wet type, and both the transformer and the oil are not approved, and the oil volume is less than 100 gallons, hourly resistance walls should be used.
And – (in the case of more than one transformer in the same room) if it is of the wet type, and both the transformer and the oil are not approved, and the oil volume is greater than 100 gallons. The walls work resistance 3 hours with an interval between each transformer and the other or make resistive walls 3 hours⏰ without breaks between Transformers with automatic system.
J- (in the case of one transformer in the room) if it is of the wet type, and both the transformer and the oil are not approved, and the oil volume is greater than 100 gallons. Hourly resistance walls work ⏰ with an automatic system, whether sprinklers, foam or mist.

09- Generator rooms are protected by automatic systems such as CO2, sprinklers, foam or mist.

10- As mentioned in the Fire protection handbook, gas systems are used with the electricity and control rooms, where CO2 systems are used with rooms where there is no human presence on an ongoing basis, and clean gases are used with constantly occupied rooms.

11- In all of the above, whether the rooms are protected or not, CO2 🧯 manual extinguishers are provided.

Sources in the link https://files.fm/u/2xph8vmd4
(M. Ali Hassan 🔥🔥 #firematrix)