Usually, according to regulatory documents, toilets do not need any lightning protection. There is no technical and economic sense in protecting it against lightning strikes, as it is much cheaper to build a new toilet. But in the described case, the customer has made a decision to protect the toilet. Considering high-ohmic soil, the customer wanted to use electrolytic grounding. The ZANDZ Technical Center received a request to calculate the lightning protection system for a toilet. Let us continue with more detailed review of our offered solution.
Calculation of lightning protection for the toilet
Facility: a toilet
Task: to perform calculation for the lightning protection system for the toilet
Solutions to fulfil the requirements for the lightning protection system of the toilet:
- The lightning protection is made in accordance with Electrical Installations Code (EIC), Rev. 7, SO 153-34.21.122-2003 "Guidelines for the lightning protection of buildings, structures and industrial infrastructure" (hereinafter referred to as SO) and RD 34.21.122-87 "Guidelines for the lightning protection of buildings and structures" (hereinafter referred to as the RD).
- The facility belongs to Class III according to RD. The system reliability shall be at least 0.9.
- The lightning protection of the facility is made using 1 x 1.5 m vertical lightning rod on anchor bolts (GL-21134), 0.5 m for the lightning arrester securing and 1 m for the top.
- A copper-plated steel wire (copper coating thickness of 70 μm min.), d8 mm (GL 11149) is used as a down conductor.
- The current collectors were installed using clamp GL-11703A. Clamp installation step is 0.8 to 1.0 m.
- The grounding arrangement consisting of 2 sets of electrolytic grounding ZZ-100-102 was installed. Grounding electrodes are installed with the step at least 6 x 9 m. The sets are connected together using copper-clad steel wire with a cross-section of 30x4 mm. The distance from the electrodes to communications and foundations should be no less than 3 m. The embedment is 0.6 m.
- According to EIC-7 issue, par.1.7.55 - Grounding devices for protective grounding of electrical installations for buildings and structures and the 2nd and 3rd categories lightning protection of these buildings and structures, as a rule, shall be common.
- If there are concrete-steel constructions, they shall be connected to down conductors/grounding device.
- Connection to the grounding device is carried out using ZZ-005-064 clamps.
Results of calculation performed using the software developed by the Krzhizhanovsky Energy Institute (OAO ENIN):
lightning discharge density into the ground is 4 strikes/square km per year.
Total number of strikes into the system is 0.0014 (once every 714 years).
Total number of blowouts is 0.00012 (once per 8,333 years).
The probability of a blowout into the system's facilities is 0.086.
The system reliability is 0,914.
Ground terminal resistance calculation:
Ом - Ohm
гор - hor
ЗУ - GA
The design resistance of the grounding arrangement is 34,64 Ohm.
Figure 2 shows hardware layout.
Table 1 includes the list of required hardware and materials.
Условные обозначения: - Key:
Молниеприемник-мачта высотой 1,5 м на анкерных болтах - 1.5 m lightning rod on anchor bolts
Проволока стальная омедненная диаметром 8 мм - Steel copper-plated wire, D 8 mm
Полоса стальная омедненная сечением 30х4 мм - Steel copper-plated strip, 30 x 4 mm
Зажим для подключения проводника - Clamp for conductor connection
Опуск токоотвода - Downdrop
Комплект электролитического заземления - Electrolytic grounding set
Figure 2. Layout of hardware for the lightning protection of a toilet
Table 1. List of material requirements.
Do you have any questions about lightning protection of the toilet or other facilities? Please, contact the ZANDZ Technical Center!