Crimping SIPs in an automatic machine: is it necessary or not?

Self-supporting insulated wire (SIP) is a popular solution for bringing electricity into a home or garage, but connecting it to a circuit breaker is controversial. Some electricians insist on mandatory crimping, others argue that it is enough to clamp the core in the terminal. Let's figure out what he says PUE-7, what risks are fraught with incorrect connection and how to avoid overheating of contacts.

The main problem is SIP aluminum conductors Over time they “flow” under pressure, especially when heated. This leads to weakening of contact, sparking and even fire. But crimping with sleeves or tips is not always possible due to limited space in the shield. So do you need to spend time on additional operations or can you get by with a standard connection?

What is a SIP and why is it difficult to connect to automatic machines?

SIP (self-supporting insulated wire) is a cable with aluminum conductors coated with light-stabilized polyethylene. It is intended for overhead power lines (OHL) and inputs into buildings. Unlike conventional wires, SIP has:

• 🔹 Aluminum core - soft metal, prone to deformation under pressure;
• 🔹 XLPE insulation - does not support combustion, but melts when overheated;
• 🔹 Bearing core (in brands SIP-1, SIP-2) - withstands mechanical loads.

The problem is that aluminum - a material with high electrical resistance and low thermal conductivity. If there is poor contact in the machine, it heats up, oxidizes and “leaks” from under the clamp. This leads to:

• ⚡ Local overheating (up to 150–200°C at the point of contact);
• 🔥 Melting of insulation and machine body;
• 💥 Short circuit or wire burnout.

B PUE-7 (clause 2.1.21) it is clearly stated: aluminum conductors with a cross-section of 10 mm² or more must be connected only by pressing, welding or soldering. But in practice, many people ignore this rule, especially when connecting to modular circuit breakers in panels.

When crimping SIP is mandatory: requirements of PUE and GOST

According to regulatory documents, crimping required in the following cases:

1. Core cross-section 10 mm² or more - according to PUE-7, clause 2.1.21 and GOST R 50571.5.52-2011;
2. Connection to powerful consumers (from 7 kW) - for example, for entering a garage with a welding machine;
3. Using machines with narrow terminals (for example, IEK BA47-29 or EKF PROxima), where the core is not securely fixed;
4. Operation under vibration conditions (for example, in a workshop or near a railway).

In other cases, crimping recommended, but not required. However, even for conductors with a cross-section of 6 mm², many electricians advise using lugs NSHVI(A) or sleeves GAto avoid problems in the future.

SIP cross-section, mm²	PUE requirements	Recommendations from practitioners
4–6	Direct clamping into terminal is allowed	Tips are desirable NSHVI(A)
10–16	Crimping is required	Sleeves GA or tips NSHVI(A)-10
25–50	Crimping + welding/soldering	Double crimping with sealing

⚠️ Attention: If you connect SIP to introductory machine (for example, ABB S200 or Schneider Electric Acti9), check the product data sheet. Some models have terminals designed only for copper wires - in this case, crimping with tips NSHVI(A) becomes mandatory.

What tools and materials will be needed for crimping?

For high-quality crimping of SIP you will need:

• 🔧 Press jaws (for example, Knipex PZ 40 or IEK PC-16U) - for crimping sleeves;
• 🔨 stripper (for example, WS-04B) - for removing insulation without damaging the cores;
• 🔩 Tips or sleeves:
  • NSHVI(A) — for cores 4–16 mm²;
  • GA — aluminum sleeves for pressing;
  • GSI-A — insulated connecting sleeves.
• 🧴 Quartz-vaseline paste (for example, EPS-98) - for protection against oxidation;
• 🔍 Torque wrench - to control the tightening force of the terminals.

💡 Helpful tip: If you are working with SIP-4 (without a supporting core), use GA sleeves with double crimp - this will prevent aluminum from leaking out. Suitable for SIP-2 NSHVI(A) with insulated flange.

Step-by-step instructions: how to crimp SIP for connection to a machine

Let's look at the process using a connection example SIP 2×16 to the introductory machine ABB S202 C40:

1. Removing insulation

   Use a stripper WS-04Bto carefully remove the insulation on 30–40 mm. Do not cut the wires as this will weaken the wire.

2. Cleaning and preparation

   Strip the vein wire brush and apply quartz vaseline paste. This will remove the oxide film and improve contact.

3. Tip installation

   Put it on NSHVI(A)-10/16 onto the core and crimp two presses press jaws Knipex PZ 40 (force - 6–8 kN).

4. Connection to the machine

   Insert the tip into the terminal of the machine and tighten the screw torque wrench (torque - 2.5–3 Nm for ABB).

5. Check

   Make sure that the tip insulation is not caught under the clamp. Test the circuit with a multimeter to make sure there is no break.

⚠️ Attention: Never use pliers instead of press tongs! Poor quality crimping leads to overheating and contact burnout. Also avoid tinning aluminum conductors - the solder breaks down over time.

What happens if you don’t pressurize a 10 mm² SIP?

After 1–2 years, the aluminum will “leak” from under the terminal, the contact will weaken, and sparking will begin. At a load of 5+ kW, this will lead to melting of the machine and a possible fire. In 30% of cases, such connections cause fires in shields.

Common mistakes during crimping and their consequences

Even experienced electricians make mistakes that ruin all their efforts. Here are the most dangerous:

• ❌ Incorrect tip selection

  Usage copper NShVI for aluminum leads to electrochemical corrosion — the contact is destroyed in 6–12 months.

• ❌ Weak crimp

  If the sleeve is crimped “by eye” with pliers, the aluminum is not fixed, and the core "walks" at the tip.

• ❌ No paste

  Without quartz vaseline paste, oxidation accelerates 3–5 times, especially in damp rooms (garages, basements).

• ❌ Terminal retightening

  Excessive force (more than 4 Nm) deforms aluminum, which leads to microcracks and overheating.

📌 Key Takeaway: 80% of problems with SIP in machines arise due to improper crimping or lack thereof. Even if the wire is “held” in the terminal, without a tip the risk of the contact burning out after 1–3 years is 40–60%.

Alternative methods for connecting SIP without crimping

If crimping is not possible (for example, in a tight panel), alternative methods can be used:

1. Special terminal blocks

   Terminals Wago 222-413 or Phoenix Contact ALU-PLUS designed for aluminum and have pasta inside. But they take up a lot of space and are not suitable for currents above 32 A.

2. Bolted connection

   You can clamp the core between two washers with grower and an M8 bolt. The downside is that it is cumbersome and requires regular checking.

3. Soldering with flux

   Use flux F-64 and solder POS-40, but remember: aluminum soldering is unreliable under vibration and high temperatures.

⚠️ Attention: If you choose Wago terminals for SIP, take only models marked "Al-Cu" (for example, 222-413). Regular copper terminals don't fit — aluminum in them oxidizes in 3–6 months.

Frequently asked questions about SIP crimping

Is it possible to connect a 6 mm² SIP to a machine without crimping?

Technically you can, since the PUE does not require mandatory crimping for conductors up to 10 mm². However, in practice recommended use tips NSHVI(A)-6to avoid aluminum “leakage” from the terminal after 1–2 years. This is especially true for machines with narrow clamps (for example, IEK or EKF).

Which cartridges are better: GA or GSI-A?

The choice depends on the task:

• GA - simple aluminum sleeves, require heat shrink insulation;
• GSI-A — already insulated, more convenient for installation in panels.

Better for an introductory machine GSI-A, since they protect against accidental short circuit.

What should I do if, after crimping, the tip does not fit into the terminal of the machine?

Problematic for cheap machines (for example, IEK BA47-29). Solutions:

1. Use narrow tips (for example, NSHVI(A)u);
2. Choose a machine with deep terminals (for example, Schneider Electric Acti9);
3. If all else fails - replace the machine for a model with terminals for sleeves.

How often should crimped connections be checked?

According to PTEEP (clause 2.12.16), the contacts in the shields must be checked:

• 🔹 Once every 6 months — for industrial premises;
• 🔹 1 time per year — for residential buildings and garages;
• 🔹 After a thunderstorm or short circuit - unscheduled.

Pay attention to darkening of insulation and a burning smell are signs of overheating.

Is it possible to use copper-aluminum adapters for SIPs?

Yes, but only certified adapters with bimetallic strip (for example, KBP-AM). Cheap "homemade" bolt and washer solutions lead to electrochemical corrosion and fire. It is better to avoid copper-aluminum transitions in shields - use aluminum tips and connect directly.

🔧 Helpful tip: If you are installing SIP in a garage or workshop where vibrations are possible (for example, from machines), add a second crimp the sleeves are closer to the insulation. This will prevent the aluminum from "fatigue".