Livestock buildings and agricultural premises (§705) — earth potential in livestock-accessible zones

The 740-horticulture/greenhouses guide already covers part of §705 (IEC 60364-7-705): the horticultural side, with IP rating and RCD types for greenhouse installations. The same standard section, however, also regulates a very different type of location within the same scope: livestock buildings and comparable animal housing (cattle sheds, poultry houses, pig sties, feed processing areas, hay/straw storage). This article covers specifically the requirements arising from the presence of livestock — a risk that simply does not exist in a greenhouse.

Why livestock is more sensitive to the same voltage than humans

An animal on four legs spans a greater distance between two contact points with the floor while walking than a human standing with both feet together, and is also physiologically more sensitive to a given current than a human. The same step-voltage level that still falls well within the safe margin for a human can already cause startle reactions, reduced milk yield or worse in livestock. §705 therefore treats livestock-accessible zones (stable floor, pasture access, drinking area) more strictly than an ordinary commercial space.

Supplementary equipotential bonding as the core measure

The core of the measure in a livestock building: all metal parts that livestock can touch or come into contact with via the floor are bonded together and to the earthing installation into a single equipotential plane, so that no relevant voltage difference can arise between two points that an animal touches simultaneously:

Metal floor grids and grids in the manure pit.
Drinking troughs and drinking nipples (often metal piping that forms an electrical path between different parts of the building).
Metal pen partitions, feed barriers and cubicles.
Other "extraneous-conductive-parts" located within reach of the livestock.

Note: this article gives the principle of supplementary equipotential bonding in livestock-accessible zones. The exact implementation requirements (grid mesh size, connection points, minimum conductor cross-section) follow from the full standard and must be determined per building layout.

Protective measures alongside bonding

Besides the supplementary equipotential bonding itself, §705 permits the usual measures from the rest of NEN 1010 — automatic disconnection of supply, RCD protection and, where applicable, extra-low safety voltage (SELV/PELV) — but the combination with bonding in livestock-accessible zones is what sets these locations apart from an ordinary commercial space.

Practical relevance

When building or renovating a cattle shed, poultry house or comparable livestock housing (including the increasingly common automatic milking systems and feed robots), it must be explicitly established which metal parts are within reach of the livestock and whether all of them are actually included in the supplementary equipotential bonding — this is a separate assessment alongside the regular earthing and RCD check of the installation itself.

Common mistakes

Treating a livestock building like an ordinary storage shed — the livestock-specific supplementary equipotential bonding from §705 is then overlooked.
Not including drinking troughs, feed barriers or cubicles in the equipotential bonding because they "don't look like an electrical part" — these livestock-accessible metal parts are precisely the core of the measure.
Confusing §705 with the horticulture/greenhouse application of the same standard section — the IP/RCD requirements from the greenhouses guide concern crop cultivation, not the livestock-specific bonding covered in this article.