Arc Flash Labelling
This article explains the requirements for arc flash labelling in the UK
What is an arc flash label?
An arc flash label (often called an equipment label) is typically fixed to items of electrical equipment to draw attention to the arc flash hazard and communicate details about the hazard.
Arc flash labels are not mandatory in the UK but may be applied to equipment as part of a managed approach to arc flash to highlight and communicate information about the arc flash hazard to those working on or near energised electrical equipment.
An equipment label often states the Arc Flash Incident Energy and Arc Flash Boundary for that item of electrical equipment, determined as part of a formal Arc Flash Study.
UK Safety Signage Legislation
An arc flash label incorporates elements of safety signage and so, in the United Kingdom, should be provided in accordance with the Health and Safety (Safety Signs and Signals) Regulations 1996. This provides the legislative basis for the provision of safety-related signs in the workplace.
Safety signs are to be used where there remains a residual risk to persons, even after adopting other risk mitigation measures.
In the USA, equipment labels are designed in accordance with ANSI Z535. However, this series of standards has some conflicts with UK and European signage legislation, particularly when it comes to wording and colours.
Arc Flash Label Contents
There is no prescriptive requirement for the contents of arc flash labels in the UK and Europe.
The contents of an arc flash label are most often provided in accordance with Article 130.5 (H) of NFPA 70E (the latest edition was released in 2023). This article states that electrical equipment such as switchboards, control panels and motor control centres that are likely to require examination, adjustment, servicing or maintenance whilst energised shall be marked with a label.
An NFPA 70E compliant equipment label must have the following:
- Nominal system voltage
- Arc flash boundary
- At least one of the following:
- Incident energy AND the corresponding working distance OR Arc flash PPE category derived from the appropriate table in NFPA 70E
- Minimum arc rating of clothing
- Site-specific level of PPE
The article has a couple of exceptions, notably Exception No. 2 which allows for the information normally provided by a label to alternatively be documented in a manner that is readily available to those persons likely to undertake activities on the energised electrical equipment. This exception only applies to supervised industrial installations which are worked on by qualified persons.
The Arc Flash Hazard Symbol
Since 2016 there has been a symbol for the arc flash hazard defined in ISO 7010 Graphical symbols ‐ Safety colours and safety signs ‐ Registered safety signs. This symbol, W042, can be used to provide a pictographic warning of the arc flash hazard and can be incorporated into signs and labels.
Arc Flash Label Design
Our approach to Arc Flash labelling aims to comply with UK legislation in terms of colours and symbols, and follow the content requirements defined by NFPA 70E.
We recommend keeping labels simple and aligned with your own Electrical Safety Management System and risk assessment process: the information on a label should help someone assess the risk and/or select appropriate control measures. Anyone who is expected to interpret arc flash labels should be given appropriate training or guidance.
The above example label is divided into three sections.
- The upper section highlights the hazard and uses the ISO arc flash hazard symbol.
- The middle section provides information about the voltage, Incident Energy, Working Distance and Arc Flash Boundary, in accordance with NFPA 70E 130.5 (H).
- The footer of the label provides information about the equipment and the circuit, and gives information about who carried out a study and when it was last completed.
Simplified Labelling
It is recommended to simplify your labelling approach as far as possible to avoid confusion and limit the need for any future re-labelling.
Examples of simplification include:
- Using a threshold Incident Energy which is aligned with other aspects of risk control, such as your site PPE rating. If your site mandates a minimum of 8 cal/cm2 arc-rated PPE, then any equipment with an Incident Energy up to 8 cal/cm2 can be labelled with this maximum, rather than the specific energy value.
- Selecting a maximum Arc Flash Boundary distance that applies to all equipment in a particularly location or site.
Label Placement
It is recommended to fit labels in a consistent location on each item of electrical equipment, for example adjacent to the rating plate or at the main incoming breaker.
Arc flash labels should not detract from any other signage or labelling fitted to the equipment.
Typically each item of equipment shall be fitted with one label, but in the case of long switchboards, or back-to-back arrangements, it may be appropriate to fit additional labels to different sections.
Where to find the label should be covered by arc flash awareness training.
Electric Shock Hazard Information
Equipment labels, especially those used in the USA, often include information related to the electric shock hazard, in addition to arc flash.
Two approach boundaries are defined as part of the electric shock precautions covered in Article 130.4 of NFPA 70E. These are the Limited Approach Boundary and the Restricted Approach Boundary. They are intended to prevent people coming into contact with energised conductors unless they are suitably qualified and have taken appropriate precautions. The boundary distances depend on the operating voltage of the equipment and are defined in NFPA 70E Tables 130.4(E)(a) for ac equipment and 130.4(E)(b) for dc equipment.
In the UK and Europe EN 50110-1 defines similar distances called the Vicinity Zone and the Live Working Zone.
It is not recommended to include either the NFPA 70E Approach Boundaries or EN 50110-1 Zones unless you are using these terms in your Electrical Safety Management System and those working on or near the equipment know how to correctly interpret and follow them.
NFPA 70E does not require you to include the shock boundaries as part of its labelling requirement, only the equipment voltage.
How can Safe Arc Solutions help you?
We can design and supply suitable arc flash labels for your site taking into account specific requirements and ensuring they meet legislative requirements. This can be as part of an initial arc flash study, a revalidation exercise, or using study data you already have. We can review the study results and develop a simplified approach to arc flash labelling.