The other wires make it more difficult to install as a retrofit. Usually radiant is installed to the flooring or just below it and the other wiring is done below that. The only space needed for the floor radiant is 2 inches or less below the flooring. The space below the radiant tubing insulated, or else the radiatn heats the lower floor as well. "Stetson explains that prior to 1984, the National Electric Code required the insulation on wiring used in farm buildings to be rated for 140[degrees]F. (60[degrees]C.). After that date, the code required a rating of 194[degrees]F. (90[degrees]C.). "It's important that the temperature rating for the wiring in the building match or exceed the rating for the fixture. If the temperature rating of the wiring is exceeded, the insulation around it becomes brittle and may break away. This allows arcing between bare wires, which causes heat that melts the fixture," says Stetson. Because most farm buildings built before 1984 have wiring rated at 140[degrees]F., Stetson used that as the maximum in his study. Amazingly, he found that with some bulb and fixture combinations, the maximum temperatures shot to 204[degrees], 261[degrees] and 262[degrees]F." http://www.findarticles.com/cf_dls/m1204/11_98/66498183/p1/article.jhtml Usually rdiatn that is applied directly to the floor material does not run over 140F, so wiring well below that whould remain unaffected. Some installers suspend tubing a few inches below the flooring and use 180F temperatures to convect upward. The affect on wiring below that tubing, especially if insulation separates themn is unpredictable. |
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