Grounding and protective measures for electrical safety. Protective measures against direct contact

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Section 1 General Rules

Grounding and protective measures for electrical safety. Protective measures against direct contact

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Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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1.7.67. The basic insulation of live parts must cover the live parts and withstand all possible influences to which it may be subjected during its operation. Removal of the insulation should only be possible by destroying it. Paint coatings do not provide insulation against electric shock, except as specifically stated in the specifications for specific products. When performing insulation during installation, it must be tested in accordance with the requirements of Ch. 1.8.

In cases where the main insulation is provided by an air gap, protection against direct contact with current-carrying parts or approaching them at a dangerous distance, including in electrical installations with voltages above 1 kV, must be carried out by means of shells, fences, barriers or placement out of reach.

1.7.68. Fencing and enclosures in electrical installations with voltage up to 1 kV must have a degree of protection of at least IP 2X, except in cases where large gaps are necessary for the normal operation of electrical equipment.

Enclosures and enclosures must be securely fastened and have sufficient mechanical strength.

Entry beyond the fence or opening the shell should be possible only with the help of a special key or tool, or after removing the voltage from the current-carrying parts. If these conditions cannot be met, intermediate guards with a degree of protection of at least IP 2X should be installed, the removal of which should also be possible only with the help of a special key or tool.

1.7.69. Barriers are designed to protect against accidental contact with current-carrying parts in electrical installations with voltage up to 1 kV or approaching them at a dangerous distance in electrical installations with voltage above 1 kV, but do not exclude deliberate contact and approaching live parts when bypassing the barrier. Barriers do not require a wrench or tool to be removed, but they must be secured so that they cannot be removed unintentionally. Barriers must be of insulating material.

1.7.70. Placement out of reach to protect against direct contact with live parts in electrical installations with voltage up to 1 kV or approaching them at a dangerous distance in electrical installations with voltage above 1 kV can be applied if it is impossible to fulfill the measures specified in 1.7.68 - 1.7.69, or their insufficiency. In this case, the distance between conductive parts accessible to simultaneous contact in electrical installations with voltage up to 1 kV must be at least 2,5 m. There should not be parts within the reach area that have different potentials and are accessible to simultaneous contact.

In the vertical direction, the reach zone in electrical installations with voltage up to 1 kV should be 2,5 m from the surface on which people are located (Fig. 1.7.6).

The indicated dimensions do not include the use of aids (eg tools, ladders, long objects).

S is the surface on which a person can be;

B is the base of the surface S;

- the boundary of the zone of reach of current-carrying parts by the hand of a person located on the surface S;

0,75; 1,25; 2,50 m - distance from the edge of the surface S to the edge of the reach zone

Rice. 1.7.6. Reach zone in electrical installations up to 1 kV:

1.7.71. Installation of barriers and placement out of reach is allowed only in areas accessible to qualified personnel.

1.7.72. In electrical rooms of electrical installations with voltages up to 1 kV, protection against direct contact is not required if the following conditions are simultaneously met:

these rooms are clearly marked and can only be accessed with a key;
the possibility of free exit from the premises without a key is provided, even if it is locked from the outside;
the minimum dimensions of service passages correspond to Ch. 4.1.

See other articles Section Rules for the installation of electrical installations (PUE).

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