Direct connection of a self-supporting insulated wire to an input device requires strict adherence to the sequence of operations, since a violation of the technology at the stage of crimping tips or selecting a terminal block often leads to local overheating of the contacts.
Aluminum conductors SIP have the property of fluidity and oxidize in air, so the use of standard twists or direct contact with contact group meter without transition elements is strictly prohibited by regulations.
Proper execution of the input assembly ensures durability electrical power equipment and eliminates the risk of fire hazards due to poor contact.
PUE requirements and regulatory framework
The main document regulating the design of electrical installations is PUE, which clearly defines how to connect wires of different metals.
According to the rules, direct connection of aluminum and copper in the input node is unacceptable due to the difference in electrochemical potentials, which leads to electrocorrosion and destruction of the contact.
To organize entry into the house, it is necessary to use special adapter terminals or busbars that provide galvanic isolation of materials.
The cross-section of the conductors must correspond to the design load and the input circuit breaker, with the minimum cross-section for SIP usually 16 mm².
It is important to consider that the wire insulation must be resistant to ultraviolet radiation and weathering if the section is laid along the facade of the building.
The distance from the power line support to the entrance to the building should not exceed 25 meters, otherwise the installation of an additional intermediate support is required.
⚠️ Attention: The use of uncertified components or violation of the rules for joining metals may lead to the energy supply organization refusing to seal the meter.
Required materials and tools
For high-quality installation, specialized tools will be required, since ordinary pliers will not provide the necessary crimping force for aluminum tips.
The main tool is press pliers with matrices of the appropriate size, which allow you to create a monolithic connection between the core and the terminal shank.
It is also necessary to prepare a set of wrenches, a hacksaw or special scissors for cutting the cable so as not to damage the insulation.
The list of consumables must include piercing clamps if the branch is made under voltage, and end couplings for sealing the ends SIP.
To connect to the meter, brass or copper-plated tips are used, selected strictly according to the cross-section of the core.
Don't forget to purchase a DIN rail if you plan to install intermediate terminal blocks inside the switchboard.
- 🔧 Press pliers with a set of dies for crimping tips.
- 🔧 Dielectric tool and cable cutting scissors.
- 🔧 Pin or fork lugs for bolted connections.
- 🔧 Insulating caps or heat shrink for sealing.
Preparing the wire and selecting lugs
Before starting work, it is necessary to properly clean SIP, removing the insulation to a length corresponding to the depth of insertion into the tip.
The aluminum core should be cleaned to a metallic shine and immediately treated with quartz-vaseline paste to prevent oxidation.
The choice of tip type depends on the design of the input terminals electricity meter: if the terminals are flat, use pin models, if for screws - ring or fork.
The crimping process is a critical stage that determines the reliability of the entire connection unit.
The tip is put on the stripped core and crimped with press pliers in several places, starting from the hole and moving towards the edge.
After crimping, you need to check the pulling force and make sure that the wire is securely fixed inside the sleeve.
Correspondence table for sections and tips
For SIP 16 mm², use tips NSh-16 or similar in diameter. For sections 25 mm² and 35 mm², reinforced models with a larger contact area are used. It is important not to use tinned copper ferrules for direct contact with aluminum without an intermediate layer.
Connection diagrams to the metering device
There are several options for organizing the input, but the most common is a circuit using an intermediate circuit breaker and a terminal block.
In this case SIP comes to the input machine, and from it a copper wire of the appropriate cross-section goes to the meter.
This scheme makes it easy to maintain the meter and replace it if necessary without disconnecting the street line.
Direct connection SIP to the meter is also possible if the input terminals of the metering device are structurally capable of clamping a large cross-section aluminum wire.
However, practice shows that it is more difficult to properly tighten a rigid wire into the narrow terminals of modern meters, so the use of a flexible copper tap is preferable.
The connection of aluminum and copper in this case is made through a terminal block or soldering using special fluxes.
| Connection type | Benefits | Disadvantages |
|---|---|---|
| Direct connection | Fewer points of contact | Difficult to install, risk of terminal breakage |
| Via terminal block | Reliability, ease of maintenance | Increasing the dimensions of the shield |
| Through the machine | Line protection, easy replacement | Additional costs for the machine |
The optimal solution is to separate the circuits: a rigid SIP goes into a flexible copper wire at the entrance to the panel through the terminal block.
Step-by-step installation instructions
Begin installation by installing support brackets and tension clamps on the building façade, ensuring correct tension SIP.
Secure the wire and lower it to the input panel, leaving a reserve for cutting.
Cut the cable, strip the insulation from the cores and strip the ends to install the lugs.
Install the ferrules on the ends of the cores and crimp them using the correct size dies.
Fix the wire in the input device or on the terminal block, observing the color marking of the phases.
Connect the output terminals to the corresponding inputs meter, controlling the tightening force of the screws.
☑️ Installation checklist
After completing all connections, it is necessary to check the circuit for short circuits and correct phasing.
Only after a successful check can you apply voltage and call a power sales representative for sealing.
Regular visual inspection of the input unit will help to promptly identify signs of overheating or loose contacts.
Common mistakes and safety precautions
One of the most common mistakes is insufficient tightening of screw connections, which leads to heating and melting of the insulation.
It is also common to use unsuitable ferrules that either become loose on the core or require excessive force to seat.
Ignoring the rules for sealing ends SIP leads to moisture getting inside the wire and its gradual destruction.
⚠️ Attention: All work outdoors must be carried out in dry weather, and when installing under voltage, dielectric gloves and goggles must be used.
An incorrect phase sequence in a three-phase connection can damage three-phase motors and other sensitive equipment.
To prevent errors, it is recommended to use color coding and ring each wire before connecting.
Compliance with these simple rules guarantees safe and reliable operation of electrical wiring for many years.
For UV protection, use black SIP, as it contains carbon black, which stabilizes polyethylene.
Is it possible to connect SIP directly to the meter without a machine?
Technically, this is possible if the meter terminals allow the aluminum core to be clamped, but safety rules recommend installing an input circuit breaker to quickly de-energize the line.
What tightening torque is required for the meter terminals?
The tightening torque depends on the diameter of the screw and is usually 2-3 Nm, the exact data is indicated in the specific data sheet meter.
Is it necessary to strip the SIP insulation completely?
Yes, at the point of contact with the metal of the tip, the insulation must be removed completely to bare metal, but no more than the length of the shank.
What to do if the meter terminals are copper?
It is necessary to use bimetallic adapter plates or tin-plated ferrules to prevent direct contact between aluminum and copper.