Lift grounding design (lift equipment) in a business center

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The task:

Object: Passenger lift in a business center.

Number of floors: 10 floors.

Perimeter of the building in plan: 58x18 m.

Soil: sandy loam, sand.

Specific resistance of the ground accepted for calculations: 150 Ohm*m.

It is required to carry out grounding calculations for the passenger lift in the business center and draw up a specification of the necessary equipment.

Solution:

1. Grounding of the lift is carried out in accordance with the drawings and installation instructions for the manufacturer, as well as electrical installation code of the 7th edition.

2. All metal parts of the lift that may become live due to insulation failure are subject to grounding: the enclosures of all electrical appliances, the guiding cabins, the cab, the shaft doors, the shield enclosures, the support frame, the motor housing, the brake magnet housing, transformers, lamp housings, etc.

3. A galvanized steel strip 30x4, item number: ZZ-502-304 is used as the grounding line in the lift engine room and the shaft. The strip is fastened by welding on the supporting corner (see sheet 3 Assembly Unit) at a distance of 10 mm from wall. The corner is fixed on the wall with dowels in increments of 1-1.5 m. In the lift engine room, the ground line is located 500 mm above the floor. The segments of the strip of the line are connected by welding.

4. Branches to grounded units are provided from the main bus. The branches are made of the same material and are connected to the main line by welding. Serial connections on equipment branches are not permitted.

Connection of the branch to the fixed structures and units is carried out by welding. The connection of the branch to devices and units mounted on shock absorbers or requiring adjustment of their position is carried out by a flexible jumper from a stranded copper wire with a cross section of 45 mm².

Grounding of metal hoses in the lift engine room and the shaft is carried out by means of a flexible jumper. The doors of the shaft are grounded by a branch from the strip and its welding to the portal of doors.

5. The cab is grounded through one of the wires of the overhead cable. Additional grounding of the cab is carried out using an overhead cable. Metal parts of the cab, control panel are connected by jumpers.

6. The grounding line of the lift equipment is connected to the main earthing bus (main switchboard of the building). The grounding device is provided in the form of a horizontal copper-plated strip of 30x4 mm, item number: GL-11075, laid at a distance of 1 m from the foundation and at a depth of 0.5 m. Perimeter of the building in plan - 58x18 m. The resistance of the grounding device, according to the calculation of Rgd = 2.25 Ohm * m.

Calculation of the resistance of the grounding device

Horizontal electrode resistance:

where:

ρ = 150 ohms per meter - specific resistance of the ground accepted for the calculations;

b = 0.03 m - horizontal electrode strip width;

h = 0.5 m - horizontal grid depth;

L_hor = 160 m - total horizontal electrode length.

The design resistance of the grounding device is 2.25 ohms.

The list of required materials:

№ п/п	Fig.	Vendor code	Name	Quantity	Weight (kg per unit)
1		ZZ-502-304	ZANDZ Strip of galvanized steel 30x4 mm	100	0.31 per 1 m
2		GL-11075	GALMAR Strip of copper-plated steel (30*4 mm)	165	0.08 \per 1 m
3		ZZ-007-030	ZANDZ Waterproofing Tape	3	0,442
4		ZZ-004-060	Flexible wire PV3-1x16 mm2	100
5		ZZ-005-064	Flexible wire PV3-1x4 mm3	50

Appendix: design in DWG and PDF

Files in DWG and PDF are available for download only to authorized users.

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