Peter,
There are several issues that need to be addressed in this area.
The needed performance is either to limit a burn to a person who might come
in contact with the part or prevent a fire if the equipment is covered by a
flammable item (such as a towel in the case of a bathroom heater).
Standards focus on these requirements in different ways, as you
have already learned.
To prevent burns consideration must be given to both the
conductivity of the material as well as the time of contact. Here's some
augmented US data from the Shriners Burn Institute which was shared here
last year.
metal glass plastic time to serious burn
deg C deg C deg C
__________________________________________
49 59 74 over 5 min
52 62 77 1 1/2 to 2 min
55 65 80 about 30 sec
57 67 82 about 10 sec
60 70 85 under 5 sec
63 73 88 under 3 sec
66 76 91 about 1 1/2 sec
68 78 93 about 1 sec
subtract 20C for handles, knobs or other purposefully touched parts
Hope that this helps...
- - - - -
Peter E Perkins
Principal Product Safety Consultant
Tigard, ORe 97281-3427
+1/503/452-1201 phone/fax
p.perk...@ieee.org email
visit our website:
http://ourworld.compuserve.com/homepages/peperkins
- - - - -
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