Thursday, November 12, 2020
The NEC sometimes requires that certain things need to be "Finger Safe." Although there is no definition of Finger safe in the NEC which causes confusion and certainly there can be many different interpretations of what Finger is safe. The International Standard IEC 60509: 1989 defines intrusion protection for both solid objects and for liquids and gives the level of intrusion prevention in ratings of 1 -7 for solid and 1-10 for liquids. This is a rating, with 1 being lowest, of well the enclosure prevents either solid or liquid materials to enter the enclosure. Most AHJs rely on this rating system to interpret "Finger Safe" and level 3 or better is considered finger safe. The intent of the NEC is to require that the finished enclosure, by design, will prevent someone from placing their finger inside the box to contact live parts. Certainly, IP level 3 would meet that intent.
The important thing to remember is this if you install something that is supposed to be finger safe. Then make sure that you cannot insert you finger and touch live parts and you should be good.
I have included here the IP ratings for both solid and liquids for your reference.
What is an IP rating?
IP (or "Ingress Protection") ratings are defined in international standard EN 60529 (British BS EN 60529:1992, European IEC 60509:1989). They are used to define levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies (tools, dirt etc.) and moisture.
What do the numbers in an IP Rating mean?
The numbers that follow IP each have a specific meaning. The first indicates the degree of protection (of people) from moving parts, as well as the protection of enclosed equipment from foreign bodies. The second defines the protection level that the enclosure enjoys from various forms of moisture (drips, sprays, submersion etc.).
First Digit (intrusion protection)
1. (or X - see the section below): No special protection. Not rated (or no rating supplied) for protection against ingress of this type.2. Protection from a large part of the body such as a hand (but no protection from deliberate access); from solid objects greater than 50mm in diameter.3. Protection against fingers or other objects not greater than 80mm in length and 12mm in diameter (accidental finger contact).4. Protection from entry by tools, wires, etc., with a diameter of 2.5 mm or more.5. Protection against solid objects larger than 1mm (wires, nails, screws, larger insects and other potentially invasive small objects such as tools/small, etc.).6. Partial protection against dust that may harm equipment.7. Totally dust-tight. Full protection against dust and other particulates, including a vacuum seal, tested against continuous airflow.
Second Digit (moisture protection)
1. (or X - see the section below): No protection.
2. Protection against vertically falling droplets, such as condensation. ensuring that no damage or interrupted functioning of components will be incurred when an item is upright.
3. Protection against water droplets deflected up to 15° from vertical.
4. Protected against spray up to 60° from vertical.
5. Protected against water splashes from all directions. Tested for a minimum of 10 minutes with an oscillating spray (limited ingress permitted with no harmful effects).
6. Protection against low-pressure jets (6.3 mm) of directed water from any angle (limited ingress permitted with no harmful effects).
7. Protection against direct high-pressure jets.
8. Protection against full immersion for up to 30 minutes at depths between 15 cm and 1 meter (limited ingress permitted with no harmful effects).
9. Protection against extended immersion under higher pressure (i.e. greater depths). Precise parameters of this test will be set and advertised by the manufacturer and may include additional factors such as temperature fluctuations and flow rates, depending on equipment type.
10. (K): Protection against high-pressure, high-temperature jet sprays, wash-downs, or steam-cleaning procedures - this rating is most often seen in specific road vehicle applications (standard ISO 20653:2013 Road Vehicles - Degrees of protection).
Comments