MICC 4H25

MICC 4H25 is a Mineral insulated cables (MICC, IEC 60702-1 grades) cable designation: MICC = Mineral insulated copper cable (MICC, MIMS): solid copper conductors in compressed magnesium oxide inside a seamless or welded copper sheath, bare or with an LSZH covering; fire survival wiring; 4H25 = 4H25: mineral insulated copper cable, heavy duty 750 V, 4 x 25 mm2, 20.1 mm over the copper sheath (22.9 mm with the LSZH covering); MICC = MICC: mineral insulated copper sheathed cable (light duty 500 V or heavy duty 750 V). light duty 500 V, heavy duty 750 V; copper sheath 70 C covered or exposed to touch, 105 C bare and out of reach (IEC 60364-5-52:2009 Table 52.1). IEC 60702-1 / BS EN 60702-1 (as the makers cite it; not held here).

1 coding system recognises this code

Mineral insulated cables (MICC, IEC 60702-1 grades)

SymbolMeaning
MICCMineral insulated copper cable (MICC, MIMS): solid copper conductors in compressed magnesium oxide inside a seamless or welded copper sheath, bare or with an LSZH covering; fire survival wiring
4H254H25: mineral insulated copper cable, heavy duty 750 V, 4 x 25 mm2, 20.1 mm over the copper sheath (22.9 mm with the LSZH covering)
MICCMICC: mineral insulated copper sheathed cable (light duty 500 V or heavy duty 750 V). light duty 500 V, heavy duty 750 V; copper sheath 70 C covered or exposed to touch, 105 C bare and out of reach (IEC 60364-5-52:2009 Table 52.1). IEC 60702-1 / BS EN 60702-1 (as the makers cite it; not held here)

What is MICC cable?

MICC: mineral insulated copper sheathed cable (light duty 500 V or heavy duty 750 V). Rating: light duty 500 V, heavy duty 750 V; copper sheath 70 C covered or exposed to touch, 105 C bare and out of reach (IEC 60364-5-52:2009 Table 52.1). Standard: IEC 60702-1 / BS EN 60702-1 (as the makers cite it; not held here).

Values and references from three makers that agree; the designer builds every reference.

Documents and pages the readings were taken from

  • Wrexham Mineral Cables, Wrexham Mineral Cables catalogue, Standard Conductor Cable tables, pp. 20 to 21: https://electricaldirect-assets.s3.amazonaws.com/product-documentation/technical/835702.pdf [seen: manufacturer]
  • nVent Pyrotenax, nVent Pyrotenax MI Wiring Cable System brochure, Pyro MI Cable System Data, p. 10: https://www.topazfiresystems.com/images/special-systems/micc/MICC%20Cable.pdf [seen: manufacturer]
  • KME Italy, KME Italy MICO mineral insulated cables brochure, Cable technical data, p. 10: https://www.kme.com/fileadmin/DOWNLOADCENTER/COPPER%20DIVISON/6._Mineral_Insulated_Cables/Mineral_Insulated_Cables_Manuals_KME_Italy_Spa/Brochure_KME_Italy_MICO_Mineral_Insultated_Cables.pdf [seen: manufacturer]

Mineral insulated cables (MICC, IEC 60702-1 grades): how to read the cable type names

Fire behaviour (EU CPR)

  • Halogen-free compound (MICC, 4H25). Under the CPR this shows in the additional classes: acidity a1 to a3 (EN 60754-2) and smoke s1 to s3 (EN 50399; s1a and s1b add the 3 m cube test EN 61034-2). The main class, Aca to Fca, depends on the whole construction.

    Typically targeted, as declared by makers for this kind of construction in the examples this site checked (not the class of this cable):

    Listed as sources, alphabetically by maker. No maker pays to appear here.

A CPR class is declared by the maker in its Declaration of Performance and printed on the sheath (EN 50575 cl 7). This decoder does not assign one. What the CPR classes mean →

Sources: EN 13501-6 draft and FprEN 50575:2014 final draft (drafts, not the published texts); IEC 60332-3-24:2000+A1:2008; EN 13501-3 draft A2.

MICC 4H25 as the cable designer builds it, 4x25 450/750 V

Overall diameter 20.1 mm, about 1,810 kg/km. Nominal values from the standard's tables for this size, computed, not a maker's data.

LayerMaterialThickness, mmOver the layer, mm
InsulationCompressed magnesium oxide (MgO)0.997.6
Metal sheath (lead or smooth aluminium)Copper0.9320.1

MICC 4H25 on a drum

The smallest drum that passes every check, for 20.1 mm and about 1,810 kg/km as the cable designer builds it. Drums as their makers print them; lengths are estimates: whole layers wound nested (each turn in the groove of the layer below), wound diameter 1.05 × OD, 50 mm freeboard under the flange rim. Cable makers' own tables print less, as they count aligned layers.

LengthDrum size (its makers)LayersGross weight
500 mKTG 12 (1250 mm flange), wood KTG drums (Europe), Bayka, KTG7 of 141,049–1,070 kg
1,000 mKTG 14 (1400 mm flange), wood KTG drums (Europe), Bayka, KTG12 of 151,985–2,009 kg

Barrel at least 15 × OD = 301 mm for a cable of this kind (Low voltage, multi-core): KTG table, the cable's datasheet wins. A load rating is the drum maker's own.

Other lengths, drums and weights: the cable drum calculator

Load it on a truck: 1000 m on its drum in the loading planner

Laying, sizes and datasheet: MICC 4H25

Current rating and voltage drop: One circuit, C: cable on a wall, 30 °C air: about 140 A. At that current over 100 m, three-phase 400 V, cos φ 0.9: a voltage drop of about 5 %. Sources: IEC 60364-5-52:2009, Table B.52.7, p. 46; IEC 60228:2023 Table 3, p. 12; IEC 60228:2023 Annex B, p. 18; IEC 60364-5-52:2009 (ed. 3.0) Annex G (informative), pp. 74 to 75 (read in the standard text) Cable size calculator: smallest section for a load, every factor shown · Voltage drop calculator: IEC 60364-5-52 method and limits

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Work with MICC 4H25

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MICC 4H25