PUE and SP do not say anything about how the wiring is independently carried out in the garage. In the meantime, this is a fire hazard class of at least P-IIA.The beginning is carried out with the calculation of the class of the garage, the figure differs individually. Much depends on the amount of fuel stored inside, including the gas tank of the car. Look at the requirements for wiring in the garage.
How to calculate the fire hazard class of the garage
The requirements for the manufacture of electrical wiring are standardized according to the hazard class of the room. The limiting factors include:
- Combustible materials: liquid, solid, explosive.
- Presence of electrically conductive ceilings, walls, floors.
- Wet works( the term from standards): washing, washing, bathrooms.
- A separate category of work on the street.
In our case, there are a lot of restrictions, let's start with the fire hazard. According to SNiP 21-02( clause 5.1.6), settlement should be carried out in accordance with SP 12.13130.Our garage falls under Appendix B of the mentioned document. It is written that the sorting according to the fire hazard category from B1 to B4 is carried out according to the total heat released during the combustion of the amount of fuel available in the room. The indicator strongly depends on the fuel category, the specific heat is different. Data from the table:
- The specific fire load up to 180 MJ / sq.m is fire hazard class B4.
- Specific fire load 181 - 1400 MJ / sq.m - fire hazard class B3.
- Specific fire load 1401 - 2200 MJ / sq.m - fire hazard class B2.
- Specific fire load from 2201 MJ / sq.m - fire hazard class B1.
The fire load is summed up according to the types of fuel present in the garage. For example, for AI-95 gasoline, the specific heat of combustion is 32 MJ / L( at an ambient temperature of 15 degrees Celsius).It means that Toyota Ipsum of 1998 contains in the depths( with full stock) 60 x 32 = 1920 MJ of hypothetical troubles. To obtain the specific fire load of the garage you need to divide the figure by the floor area. With a wall size of 3 x 3 meters, the room clearly falls into category B3.And in the garage a little more( 5 x 6 = 30 square meters. M), the fire hazard class dropped to B4.
Pay attention, divide, according to SP 12.13130, you need at least 10. But it is not allowed to allocate a reserve of fuel everywhere. The class of fire hazard readers will consider for themselves.
Then you need to apply specific rules and regulations. Moreover, for those who decided to switch to liquid( compressed) gas, different instructions are mentioned. An additional calculation will be required, during which it turns out that the fire hazard class of the room has increased to A or B. The formulas will be useful:
- The critical volume of the room is calculated: V = 1000 M / 2,886 = 346.5 M, where 2,886 is mass in grams per meter,maximum allowable for rooms without emergency ventilation. M - the mass of gas thrown into the room. To do this, specify the amount of fuel filled.
- Allowed to consider the work of emergency ventilation. In this case, the coefficient 2.886 is multiplied by K = А Т + 1. Where A is the frequency of air renewal in the garage due to the action of the emergency system, T is the period during which the leak will last. The permissible volume of the garage may be significantly reduced by moving to a lower hazard class.
- The resulting value is compared with the free volume of the room. It is formed by subtracting the occupied space from the dimensions of the walls. If calculation is difficult, it is allowed to take the amount of free garage space in the amount of 20% of the total.
- If it turns out that the minimum estimated safe garage volume is less free, the category automatically becomes the highest - A. Otherwise, only B2.
garage Rules for placing electrical equipment
Head for clipping, that at least half of motorists are trying to use sockets on the street. In the latter case, there is an explicit indication of the ПУЭ 7 to supply 220 V power through a differential automatic machine with a threshold of not more than 30 mA.The actual conditions of the street are equal to the bathroom. It means that it would not hurt to know two more conditions: it is allowed to conduct power with low voltage( up to 50 V AC).
If the room falls into the fire hazard and explosion hazard class A, it is equipped according to category B1a( clause 7.3.41 of ПУЭ 6) according to ПУЭ 7( protective sheath).There are a whole bunch of additional requirements:
- Installation of emergency ventilation with an exchange rate of at least 5. This equipment is electrical, therefore, must be taken into account in the system design process. Simultaneously with the activation of emergency ventilation, other consumers are de-energized.
- Installation of sensors monitoring the content of hazardous gas. Equipment is also classified as electrical, therefore, it is taken into account. The control sensors and the emergency ventilation system are provided with wiring according to reliability category 1 according to EIR 7.
- . Part of the garage walls should be replaced with light-reset structures according to SNiP 2.09.02.
- Electrical equipment is installed in explosion-proof. SP 31-110 says: it is required to use lamps according to the PES 6 p. 7.3 and 7.4( in the new edition are excluded).
In PUE 7 regarding electrical installations in hazardous areas they write:
- Explosion-proof equipment is used according to GOST 17494. The degree of protection of the housing by IP is determined according to the table( see clause 7.3.66 of OIL 6).Outdated standards are not considered by chance - in the new issue of the explosiveness of gas subtly costs. In class B1a premises, installations with increased reliability against an explosion( sparking or heating above 80 degrees Celsius) or ordinary ones, but with an IP54 package( not heating above 80 degrees Celsius), are used.
- Stationary lamps with enhanced protection against explosion are used in the garage, and portable lamps are taken to be explosion-proof. This equipment is expensive. It is believed to carefully evaluate the class of its own premises in terms of fire risk, so as not to give extra money. It is allowed to use devices with slotted light guides.
- Switchgears( panels) are prohibited to be installed in hazardous areas of any class. Installation must be carried out outside the garage. In some cases, it is allowed to install separate columns if the degree of protection is not lower than that in table 7.3.11 of ПУЭ 6.
- The use of non-insulated wires in hazardous areas is prohibited. According to the classification, on the territory of the BI and BI-A objects, only cables with copper conductors are used. Aluminum is prohibited( due to the greater heat dissipation).Including cables from the mentioned metal.
- Grounding conductors detect insulation similar to phase circuits.
- Never use cable joints or branching couplings with the exception of intrinsically safe circuits. As for the fillers do not say exactly. There is no explanation of what caused the requirement( heating or sparking).The creation of cable ducts under the floor is not encouraged, which should be filled after sanding.
- All tires are insulated. One-piece joints are made by welding or crimping( for soldering silent).Of course, tires are made of copper. Bolted connections that do not allow unscrewing are permitted.
- Potential equalization is required. In theory, the car body is also included in this circuit by a temporary connection. Any electrical equipment is grounded through the socket and is zeroed( local wires).All lamps( including expensive ones) are subject to this procedure.
Lists the requirements for hazardous areas, and there are still fire-hazardous garages. Their classification is given in paragraph 7.4 of the old OSP( sixth edition).From what has been said, it is clear that the type of fuel, the size of the gas tank, spare canisters, the area and type of garage design greatly influence the cost of equipment. If there are no machines inside, as well as flammable substances, the measures are significantly softened. Putting a gas tank inside the garage will be tight.
It does not hurt to make a lightning conductor, to him - the ground loop. Recall that if you do not want to use the cable scheme, the peak is erected approximately in the center of the roof of the garage. Formulas and links, see the corresponding review, there is already indicated how to make a ground loop. The tire is made with a strip of steel not less than 4 mm thick or with a rod with a diameter of 6 mm or more. The underground part consists of two or more iron stakes, unpainted, with a length of 2.5 meters or more. The distance between them is chosen from three meters.
It is logical to lay the ground loop in the construction of the garage. This will be necessary for the system of zeroing( conducted by a rod of 6 mm, if the area is not explosive).Equalization of potentials is carried out separately from the power supply network. Grounding will have to lead out of the ground loop. You will need to ground the switchboard body, bring the bus inside to connect consumers.
Experienced people recommend taking a copper core for at least 4 square millimeters. This is in the case of the use of welding, and is not close to the garage where the vehicles are filled. Electrical wiring in the garage is made on the contours: separate lighting, sockets, hoods. If consumption is planned for a distribution point of 6 kW( inclusive), the core goes without branching and couplings directly to the shield. Only differential automatic machines should be installed under the installation of electrical wiring in the garage. Most are against, because the cost is much higher than usual. Then make an exception for lighting.
Lamps are better to take on 12 V, LED, under the pin or screw cartridges. It is possible to power the local network through a special converter. Place it on the DIN rail in the distribution box right next to the machines. Start making your garage wiring with a careful study of the components of the local supply system. The scheme can vary greatly depending on the environment.
What is the result with the garage
They told how to conduct electrical wiring in the garage, how to determine the class of fire and explosion hazards. Now you know where to look, where to look.
But now it is allowed to put the hood on the cellar: 12 V systems are allowed even in wet rooms, there will be no difficulties. When doing electrical wiring in the garage, break the room into parcels, see which appliances and where to use. You may want to get rid of condensation in the cellar or to dry vegetables and fruits in the garage. All this is real, just need to take into account the requirements, and then think about how to save money on reducing the requirements by changing the conditions.