How to lay the cable underground - practical tips

Requirements for electrical work

The first thing you need to tell you about what regulatory documents can affect how you willto install electrical wiring in an earthen trench. So, we recommend that you take into account the following limitations in accordance with the rules of electrical installation, SNiP and GOST for electrical work:

• The depth of the cable in the ground must be at least 70 cm. If the length of the underground line is less than 5 meters and the wiring is additionally protected by a pipe,at a depth of 50 cm, as shown in the picture.
  
• It is forbidden to draw a line under the foundation of the house. The minimum distance from the basement should be 60 cm. If you need to lay a cable from the house to the bath( or another structure) through the foundation, be sure to protect the transit power line with a steel pipe.
• The distance between two cables in one trench must be no less than 10 cm, on the basis of which the width of the technological ditch is selected.
• From trees, it is necessary to retreat at least 2 meters for wiring in a trench, and from bushes - at least 75 cm. If you additionally organize the protection of the cable line by a pipe, this rule can be neglected.
• The distance from the water supply and sewerage should be more than 1 meter, and from the gas pipe - at least 2 meters.
• If you can not do without crossing the cable lines in the trench, the separating layer of land should be from half a meter.
• The conductor itself must be armored, specially designed for laying underground. The armor layer is necessary to protect the wiring from rodents and mechanical damage.
• If you decide to lay a cable with a special winch that unwinds the drum, the mechanism must be additionally equipped with a stop( SNiP p.3.58).The limiting device allows you to make a conductor with a reserve( snake), so that there is no stretching of the line.
• If you need to make an electrical connection yourself under the ground, use special couplings, as shown in the photo.
• For additional protection of the power line under the ground( for example, with strong soil subsidence), you can use an asbestos-cement pipe or a special cable structure made of bricks( stacked across the trench, as in the photo below).It is strictly forbidden to use hollow bricks.
• Be sure to lay the signal tape with the inscription "Caution, cable!" On top of the conductor laid in the ground.

Given these requirements and rules, you can be sure that laying the cable in the trench will not endanger you and the house wiring line! Of course, this is not all the restrictions that exist in the rules of the EE and SNiP, but for home conditions of the given requirements it will be enough even if the site is connected from the post to the house.

The technology of laying by yourself

Here we have come to the main issue of the article, in which we will consider how to lay the electrical cable in the ground on its own. For the instruction to be convenient and understandable, we will provide it step by step.

1. Draw the layout of the wiring in the trench, on which note the exact distance from the house, garden buildings and plantings, according to regulatory documents. If the underground wiring is used to connect street lighting in the country, be sure to specify the location of the lights.
2. Mark the area of ​​the villa site with pegs and rope, then excavate the trench according to the layout. After excavation remove from the prepared trench stones, possible splinters of glass or pieces of metal, which can further cause damage to the electrical wiring under the ground. Immediately install the light supports, if required.
3. On a compacted bottom, make a uniform cushion of sand, about 5-10 cm thick.
4. Route the conductor in the ground, as shown in the photo. For wiring in the trench, it is recommended to use AVBbShv cable with aluminum conductors or a more expensive version - VBbShv, with copper conductors.
5. Check the finished power line with a megger that will detect a short circuit, if any.
6. Remove the charge from the cable, for which connect the veins with the armor and close everything to the ground. Act carefully, while protecting yourself with rubber boots and gloves. It is advisable to invite a partner just in case.
7. Protect the wiring( if necessary) with an asbestos cement or plastic pipe( eg HDPE).If you have chosen to protect the asbestos cement pipe, cut it along, lay the conductor inside and connect the material with adhesive tape. This technology will quickly release the wiring while repairing it.
8. Take a picture of the network from trenches to know exactly where the cable passes in the ground in the garden. By the way, it is better to save the drawing, too.on it there are designations of all distances at a lining of a line from the house, a protection, etc.
9. Fill the trench with sand. The layer should be uniform, about 15 cm. After filling it should be carefully tampered.
10. On the sand, lay the signal tape with the designation that under it the wiring was done.
11. On top of the tape, fill the remaining ground with a slide that after a few rains settles and aligns with the surface.
12. Once again, make a measurement using a megger.

That's the whole technology of laying the cable under the ground in the suburban area. As you can see, it's not so difficult to draw a line at home. More time and effort will go to land work - trench digging.

Practical advice from

specialists In addition to the above instructions, we recommend that you familiarize yourself with some tips for laying the cable in a trench:

1. Use only a special armored conductor. Such brands as KG, PPPP and AABL are better not to choose. The first two cables do not have sufficient protection, and to work with the last brand of the conductor you need certain skills.
2. The diameter of the metal pipe, which will pass through the foundation of the private house( if this is necessary), should be 2-3 times larger than the diameter of the electrical house itself.cable.
3. If the depth of freezing of the earth in your region is deeper than 70 cm( the depth of the trench), be sure to fix the protective tube so that it does not tear and does not deform.
4. Do not use a plastic corrugated pipe( DAC) to protect the electrical wiring under the ground. A year later the corrugation will collapse and all its protective properties, which are already so weak, will be lost.
5. Try not to lay the conductor under such high load zones as: playground, parking lot, garden paths.
6. A single opinion or rules in the regulatory documentation, relative to the minimum section of the cable for laying in the ground there. In practice, the cross section of 10 mm2 for copper and 16 for aluminum is most often used. Focus only on calculating the cable cross-section for power and current, and also consider that the line should be armored.

Nuances for laying in the winter

Well, the last thing I would like to tell you is whether it is possible to lay the cable underground under low temperatures, and in particular in winter. Electrical work in winter is allowed, but the following rules and regulations must be observed:

• Before laying the wiring in a trench, the conductor must be heated in a warm room or with a transformer. The last method to use is not recommended, if you have not encountered it before, sincefor this you need certain skills.
• After heating, it is necessary to quickly lay the power line. If the temperature on the street is not below -10 oC, you have an hour of time, from -10 to -20 oC - no more than 40 minutes, below -20 oC - a maximum of half an hour. If the temperature is lower in winter, do not perform electrical wiring.
• Without preheating, it is allowed to lay the cable underground under the following conditions: if the temperature is not lower than -5 ° C, and the high-pressure conductor itself;if the temperature is not lower than -7 оС and the cable is protected by insulation, -15 оС if the PVC insulation is rubber or -20 оС in case the insulation of the conductors is represented by a polyethylene sheath or rubber and an additional lead sheath.

That's all I wanted to tell you about how to make a cable laying in the ground with your own hands. We hope our practical advice, instructions and also the provided standards will help you when installing at home!

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