Why is the calculated result lower than the nominal rating?

Under real operating conditions the ambient temperature rises, heat dissipation inside a conduit is poor, and aluminium has a higher resistivity than copper — so the base ampacity has to be corrected accordingly.

Is DT-16 overkill for a 1.5 mm² conductor?

The tool always rounds up to the next standard size for safety margin. If you are cost-sensitive, contact our engineers and we can confirm a smaller size.

Why is the power in kW converted to current before selecting a terminal?

The terminal tables are indexed by base ampacity (amperes), so selection is fundamentally a current decision. System voltage, phase count and power factor determine the current that corresponds to a given power: I = P/(U·cosφ) for single phase and I = P/(√3·U·cosφ) for three phase — the standard conversions of electrical engineering.

Why does the tool still back-calculate from the cross-section after I entered the power?

The power field is optional. When left blank, the tool looks up the terminal table by conductor cross-section and back-calculates the maximum sustained power for that size from the corrected ampacity, so you can check your design margin.

Can I change the default power factor of 0.85?

Yes. Motor loads typically use 0.8–0.85, resistive loads (heating, incandescent lighting) use 1.0, and loads behind a variable-frequency drive can use 0.95 or above. You can enter any value between 0 and 1 in the form.

Why can copper and aluminium not be crimped directly together?

Direct copper-to-aluminium contact causes galvanic corrosion; the contact resistance rises rapidly and the joint heats up. A DTL series (copper-to-aluminium transition terminal) must be used for these applications.

Can the aluminium side of a DTL terminal be assembled and disassembled repeatedly?

Not recommended. A DTL terminal forms a gas-tight connection after crimping, and disassembly destroys the oxide layer — the surface has to be re-cleaned or the terminal replaced.

Can I order directly from the calculation result?

Yes. Click the "Get a Quote" button and the recommended model is carried over into the inquiry form automatically; you only need to add the quantity and the required delivery date.

Cable Lug Calculator

Free online calculator that recommends the right copper lug, crimp terminal or pre-insulated terminal for your conductor cross-section, load power and operating conditions.

Cable Lug & Crimp Terminal Selection Calculator

Enter the conductor cross-section, material and ambient temperature to get a recommended copper lug, crimp terminal, pre-insulated terminal or copper-to-aluminium transition terminal.

Selection Parameters

All fields are required. If you are unsure about one of them, pick the most common scenario.

Conductor Cross-section*

Conductor Material*

Ambient Temperature (°C)*

Installation Method*

Terminal Type*

System Voltage (V)*

Phase*

Load Power (kW)

Power Factor (cosφ)

No matching model

Recommended Model

Terminal Selection Result

Recommended Model	—
Stud Size	—
Crimp Die	—
Base Ampacity	—
Corrected Ampacity	—
Conclusion	—

Power Information

System Voltage	—
Phase	—
Power Factor	—
Load Power	—
Target Current	—
Corrected Ampacity	—

⚠️ Insufficient ampacity

Correction factors:

Temperature —
Installation —
Material —

Get a Quote Select Again

How to Use

Based on the conductor cross-section, load power (or the reverse calculation) and the operating conditions you provide, this tool recommends a matching copper lug, crimp terminal, pre-insulated terminal or copper-to-aluminium transition terminal using the standard correction factors of electrical engineering (GB/T 4703 / IEC 61238). The result is for reference only — please confirm with our engineers before placing an order.

Formulas

Ampacity correction:
  Corrected ampacity = Base ampacity × Temperature factor × Installation factor × Material factor

Power → target current (for selecting by power):
  Single phase:  I = P × 1000 / (U × cosφ)
  Three phase:   I = P × 1000 / (√3 × U × cosφ)

Back-calculating the maximum sustained power from a known cross-section:
  Single phase:  P = U × I × cosφ / 1000
  Three phase:   P = √3 × U × I × cosφ / 1000

Frequently Asked Questions (FAQ)

Why is the calculated result lower than the nominal rating?: Under real operating conditions the ambient temperature rises, heat dissipation inside a conduit is poor, and aluminium has a higher resistivity than copper — so the base ampacity has to be corrected accordingly.
Is DT-16 overkill for a 1.5 mm² conductor?: The tool always rounds up to the next standard size for safety margin. If you are cost-sensitive, contact our engineers and we can confirm a smaller size.
Why is the power in kW converted to current before selecting a terminal?: The terminal tables are indexed by base ampacity (amperes), so selection is fundamentally a current decision. System voltage, phase count and power factor determine the current that corresponds to a given power: I = P/(U·cosφ) for single phase and I = P/(√3·U·cosφ) for three phase — the standard conversions of electrical engineering.
Why does the tool still back-calculate from the cross-section after I entered the power?: The power field is optional. When left blank, the tool looks up the terminal table by conductor cross-section and back-calculates the maximum sustained power for that size from the corrected ampacity, so you can check your design margin.
Can I change the default power factor of 0.85?: Yes. Motor loads typically use 0.8–0.85, resistive loads (heating, incandescent lighting) use 1.0, and loads behind a variable-frequency drive can use 0.95 or above. You can enter any value between 0 and 1 in the form.
Why can copper and aluminium not be crimped directly together?: Direct copper-to-aluminium contact causes galvanic corrosion; the contact resistance rises rapidly and the joint heats up. A DTL series (copper-to-aluminium transition terminal) must be used for these applications.
Can the aluminium side of a DTL terminal be assembled and disassembled repeatedly?: Not recommended. A DTL terminal forms a gas-tight connection after crimping, and disassembly destroys the oxide layer — the surface has to be re-cleaned or the terminal replaced.
Can I order directly from the calculation result?: Yes. Click the "Get a Quote" button and the recommended model is carried over into the inquiry form automatically; you only need to add the quantity and the required delivery date.