With K&T, there is no ground wire, just hot and neutral. There is no outer insulation layer. The wiring is protected only by a black fabric-based insulation (having asbestos, tar or other additives). The hot and neutral wires are individually attached to the framing, using white porcelain insulators; the insulators ("knobs") hold the wires away from the framing and combustibles. The "tubes" protect the wiring where it penetrates through wood, such as wall studs and floor joists. Connections are made using solder and electrical tape.
K&T was originally designed to not touch anything, as heat buildup or chafing was thought to destroy it over time. In the '70s, we started insulating older attics, and in case after case, older wiring was covered by insulation, despite admonitions against it. A wire inspection is required when insulating over K&T, by the way.
By default, this wiring is not grounded, it is old, the insulation is substandard and the intent of the designers to keep it from other materials has been overlooked in deference to energy issues. Despite all this, and despite the insurance industry's recent paranoia, it seems to be holding up fairly well in the housing stock.
Q: What is the best way to decommission a swimming pool?
A: Disconnect all the electrical and water pipes. Take a jackhammer and blow several holes in the bottom to allow water to drain. Knock the outer edges into the hole, and fill it with dry dirt or gravel.
Q: Is it feasible or advisable to raise a sunken concrete patio? I am wondering if it will sink further, and if it would be better to just take it out and start over.
A: They can't be raised in all cases, so talk to a contractor that does this work about your specific situation. In my experience, people who have had this done have been fairly well satisfied, when dealing with a reputable contractor.
Q: Some mold has recently appeared in my attic. A new efficient gas furnace was installed not too long ago in my basement. It is a "condensing" furnace in an enclosed area (which I had to pay extra for). They installed a pipe to the attic to pull air in for combustion, and the plastic exhaust pipe runs up alongside it. The exhaust pipe goes through the roof to the outside. When they ran these pipes up through the two floors they cut out the little sheet metal barriers between floors that were in place from the old furnace. I can see around the pipes from the attic all the way to the basement through a little hole about one foot square. Is this opening somehow contributing to the mold growth? I am aware that some of the attic vents are blocked and the insulation vapor barrier is upside down, but the mold is new and this is the only thing that has changed. The house was built in 1975. Am I way off base here?
A: Sounds to me like you nailed it. The open chase that the vent pipes go through is allowing it to act like a chimney, sucking warm, moist air up from the lower floors and depositing it in the attic, where it condenses on the cold surfaces, causing mold. Having the furnace combustion air source pulling more air up into the attic just exacerbates an already ugly situation. Turn your insulation over, open the vents, seal the chase at each floor level and extend the intake air to the exterior, alongside the exhaust. You may also want to physically remove the mold if it is widespread — use a respirator with HEPA filter.
Darrell Hay answers readers' questions. Call 206-464-8514 to record your question, |
