Part 1 – Enclosure Types, Product Mobility, and Intended Use
IEC 60950-1, the international standard for safety of Information Technology Equipment (ITE), contains several requirements that affect the design of IT product enclosures. These include:
- resistance to physical abuses for all enclosure types;
- proper flammability rating and resistance to shrinkage or distortion at high heat for enclosures made of polymeric materials;
- openings which prevent the spread of fire and flame from the inside;
- protection against access to hazardous parts, both by touching with the finger, and insertion of conductive foreign objects.
This article introduces the basic concepts covered in IEC 60950-1, and offers suggestions for effective and compliant product enclosure designs. This series explores the IEC 60950-1 standard in detail, so we recommend that you have a copy at hand.
To begin, let’s first examine the three enclosure types defined in IEC 60950-1.
- The mechanical enclosure provides protection against access to mechanical and other physical hazards, such as moving parts, hot surfaces, radiation, and chemical. The mechanical enclosure generally contains all the parts of the product.
- The electrical enclosure provides protection against access to parts and circuits operating at hazardous voltages or energy levels, and also parts that are in telecommunication network (TNV) circuits.
- The fire enclosure minimizes the spread of fire or flames from within, should ignition occur.
Any one of the enclosures may be contained within another; for example, the mechanical enclosure may contain an internal fire enclosure. It’s also quite common for a single physical enclosure to function as all three of the defined enclosure types. A perfect example of this is the desktop or direct plug-in power adapter; the single plastic enclosure serves the function of the mechanical, electrical, and fire enclosure.
Next, let’s consider the mobility of the equipment, as defined in IEC 60950-1.
- Moveable equipment weighs less than 18 kg and is not fixed, or is provided with wheels, castors, or other means to facilitate movement by the operator. There are two sub-categories of moveable equipment:
- Transportable equipment is intended to be routinely carried by the user, such as laptops and tablets.
- Hand-held equipment is intended to be held in the hand during use. Common examples would be a smartphone or wireless mouse.
- Stationary equipment is not moveable.
The intended use, locations, and orientations must all be considered before we begin enclosure design. Will the product sit on a table-top? Will it be used in a horizontal or vertical orientation, or both? If the intention is one orientation, is it reasonably foreseeable that it will be used in another position, either purposefully or not? Is it or can it be wall-mounted?
It is vital to consider all intended and reasonably foreseeable uses, locations and orientations, particularly when planning for openings in the enclosure, such as ventilation openings.
Before we begin our enclosure design, let’s answer a few basic questions.
- What are the physical hazards in the product? (Is a mechanical enclosure required?)
- What are the electrical hazards in the product? (Is an electrical enclosure required?)
- Is there a potential ignition source in the product? (Is a fire enclosure required?)
- Where is the product meant to be used?
- What are the reasonably foreseeable misuse orientations?
- Will the enclosure have access doors or covers intended to be routinely opened by the user?
The IEC 60950-1 regulates product enclosure design for user safety; it defines enclosure types, as well as the mobility of the equipment to accurately rate the potential hazards for consumers. Before enclosure design can begin, it’s crucial for designers to understand the IEC 60950-1 and work within its guidelines to design a compliant product.
Part 2 of this series will examine the fire enclosure in more detail.
ACS product safety engineers can provide assistance to your design team with preliminary design and construction reviews, working remotely, at your facility, or at our Buford facility. The preliminary review output is a list of findings of non-compliances, and some suggested options to bring the product into compliance. The preliminary evaluation includes review of the product design and construction, along with review of required product markings, and required elements of the user manual / installation instructions.
Get in touch for more information on ITE Requirements.
ACS engineers can help your team understand specific elements of the IEC 60950-1 standard which relate to your product. We can provide safety-critical component review. We can provide a test program overview, so that you will know what tests will be performed, how many samples to provide, what operational modes and product configurations should be tested; and the support equipment you will need to provide for the testing.
When it’s time for ITE product safety certification, ACS offers certification options for all regions, including Underwriters Laboratories certification for North America, TUV SUD certification for North America, and the IECEE CB Scheme certification through TUV SUD.
Tags: Understanding ITE