Stray voltage in dairy sheds can agitate cows and impact on their milk production and to help overcome this problem, Standards New Zealand has published a new handbook on electrical installations in dairy sheds.

It provides the recommended trade practice on how to build dairy sheds that minimise stray voltage, which can disturb cows.

Users of the handbook include electricians and electrical designers that help to build dairy sheds.

It may also help farmers and farm vets to recognise when an electrical problem is affecting cows. Stray voltage can be caused by faulty installation or bonding within a dairy shed.

When this happens, it can cause a micro-shock and the cows may recoil when entering or exiting the shed. They may cause damage to themselves or the shed, or their milk production may drop by up to 30 per cent.

The new handbook outlines how to fix problems with stray voltage in dairy sheds. It covers the correct electrical installation practices for new dairy sheds, to reduce the exposure of cows to stray voltage. It also provides recommendations for upgrading existing dairy sheds where there are problems with stray voltage.

Alan Cuthbert, who is chair of the committee that developed HB 6117, says this is a new document for New Zealand.

'We initially wrote it as a technical report and issued it for public comment. The comments we received were helpful and meant we could improve the document and raise it to the level of a handbook.

'Once the handbook has been in use in typical installations for a short period, the committee aims to review it and convert it to a standard.”

Alan says the handbook allows for alternative use of the TT system of supply, which can help to reduce stray voltage.

'Use of the TT system is not currently permitted by the Electricity Safety Regulations, but this is under active consideration.

'If use of the TT system is approved, amendments will be required to AS/NZS 3000 to cover the particular TT system requirements.”

Find out more, www.standards.co.nz