Blog Archives

Magnetic Fields from Panels and Subpanels

Posted by on 25/ 11/ 15

Many electrical panels and subpanels emit substantially elevated magnetic fields. This problem arises because breaker and neutral bus bars are configured so that the neutral and hot wires are separated once fastened in place, causing magnetic fields as discussed earlier. Some electrical panels are configured with the neutral bus bar split to run alongside the breakers. To cancel the fields, the hot and neutral wires would be the same length and installed beside one another. We recommend that such reduced field configuration panels and wiring be specified as indicated below:

• Panels and subpanels shall be configured so that hot and neutral field cancellation is possible.

• The following panels and subpanels are acceptable: Siemens EQIII, standard load center electrical panels, and subpan...

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OTHER NATURAL FLOORINGS

Posted by on 25/ 11/ 15

The materials in this group—bamboo, coconut palm, and cork—are engineered to make them easier to install and more durable. And their beauty is 100 percent natural.

Bamboo flooring sounds implausible to people who visualize a floor as bumpy as corduroy. However, bamboo flooring is perfectly smooth.

It is first milled into strips and then reassembled as multi-ply, tongue-in-groove boards. Available in the same widths and lengths as conventional hardwood, bamboo boards are commonly 58 in. to 58 in. thick. Bamboo flooring can be nailed or glued. But if you glue it, allow the adhesive to become tacky first so the bamboo doesn’t absorb moisture from it.

Bamboo flooring comes prefinished or unfin­ished, and can be sanded and refinished as often as hardwood floors...

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TRENCH SYSTEMS

Posted by on 25/ 11/ 15

Trench systems are the least expensive versions of special septic systems. They are comparable in many ways to a standard pipe-and-gravel bed system. The main difference between a trench system and a bed system is that the drain lines in a trench system are separated by a physical barrier. Bed systems consist of drainpipes situated in a rock bed. All of the pipes are in one large

Подпись: been there done that When working with a trench system, there should be only one pipe in each trench. But, always follow the plans and specifications that have been approved by the local code officer. bed. Trench fields depend on separation to work properly. To expand on this, let me give you some technical information.

A typical trench system is set into trenches that are between one to five feet deep. The width of the trench tends to run from one to three feet. Perforated pipe is placed in these trenches on a six-inch bed of crushed stone. A second layer of stone is placed on top of the drainpipe...

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Optimal risk-based pipe culvert for roadway drainage

Posted by on 25/ 11/ 15

The basic functions of highway drainage structures are (1) as hydraulic facil­ities to safely convey floods under highways during all but the most severe flooding conditions and (2) as portions of the highway to move highway traffic freely over stream channels. There are three general types of drainage struc­tures: bridges, box culverts, and pipe culverts. Conventionally, bridges refer to structures measuring more than 20 ft along the roadway centerline (AASHTO, 1979). Box culverts are usually built of concrete with rectangular openings. Pipe culverts can be in various geometric forms, such as circular, arch, etc., and can be made of several different materials, such as steel, cast iron, concrete, or plastic.

The design of highway drainage structures involves both hydraulic design and st...

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Transverse Drains in Rigid Pavements

Posted by on 25/ 11/ 15

Transverse drains are similar in construction to lateral drains, except that they run perpendicular or slightly skewed to the centreline of the carriageway (Kasibati & Kolkman, 2006). They are mostly used to drain water that may infiltrate into the road bases and sub-bases at joints, see Fig. 13.18 (FHWA, 1980).

It is important to provide drains at joints in rigid pavements as the joints’ seal­ing can deteriorate with time allowing water to flow into the pavement. Perforated pipes are usually used as transverse drains and they may empty directly into the side ditches. Pipes as transverse drains are classified as passive drains, meaning that they do not constrain the water movement but they are placed in the hope that water will find its way into the drain...

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Intangible factors

Posted by on 25/ 11/ 15

Besides the economic factors that can be quantified in monetary terms in the design of hydrosystems, there are other intangible factors that are noncommen­surable and cannot be quantified. Some of the intangible factors might work against the principle of economic efficiency. Examples of intangible factors that are considered in the design and planning of hydrosystems may be potential loss of human lives, stability of water course, impacts on local society and environ­ment, health hazards after floods, litigation potential, maintenance frequency of the systems, and others. The conventional optimal risk-based design yields the most economically efficient system, which may not be acceptable or feasible when other intangible factors are considered.

As more intangible factors are considered ...

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NOISE BARRIER SELECTION

Posted by on 25/ 11/ 15

Presuming acoustical requirements are met, selection is usually based on cost and aesthetics. Costs that must be considered include site preparation, the barrier material itself, foundations, fabrication, erection, and maintenance. Aesthetics should be judged with the involvement of personnel with diverse backgrounds, and public participation should be encouraged. However, there are numerous factors that go into the final selection. Some factors that should be considered in wall selection are summarized in Table 9.1.

The reasonableness of constructing a noise barrier can be judged from a cost-benefit analysis. For example, Minnesota uses the following procedure. The benefit is based on the summed insertion loss (noise reduction) for each residence in the first two rows

TABLE 9...

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Californian Drains

Posted by on 25/ 11/ 15

So-called “Californian Drains” are sometimes used. These consist of parallel and closely-spaced tubes, arranged vertically or sub-horizontally. The tubes can be perforated or grooved and are installed into natural ground or fill. The main objective of such drains is the reduction of pore water pressure in a certain area, in order to lower the water level or treat a retained water pocket. A typical application, to stabilise a slope with high pore water pressures, is illustrated inFig. 13.17.

Fig. 13.17 “Californian drain”

13.4.2 Drainage Layers for Rigid Pavements

In a rigid, concrete, pavement structure, water filters mainly through

• open joints between the concrete slabs;

• open pavement-shoulder joints; and

• and the areas between the verges and the pavement.

Unles...

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FINISH DETAILS

Posted by on 25/ 11/ 15

Подпись: Finish applied with care at the right places goes a long way toward making a house look pleasing to the eye. This includes installing doors and windows that are square, plumb, and level. (Photo by Rich Ziegner.)

Once there is a completed house shell, it’s time to turn attention to the finishing details. Of course, much of this work—installing plumbing, heating, and electrical systems, roofing, and drywall, for example—is outside the scope of this book. But there is still plenty of carpen­try work to do. In frame carpentry, it often doesn’t matter if there are small gaps left here and there as the house is built. These gaps will all be covered "in the finish," as we say. What matters is that the house frame is square, level, straight, and plumb.

But more is needed when you start doing the finish work. I think it helps to approach finish carpentry with a differ­ent mindset than with frame carpentry. The work you do as a finish carpenter will be seen daily for the life of a build­ing...

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Install the baseboard trim

Posted by on 25/ 11/ 15

Before installing baseboards, use a putty knife first to clean any excess joint compound from the corners. Then clearly mark (or re-mark) the location of the studs on the floor. If the gap between the bottom edge of the drywall and the floor is greater than 1 in., take the time to fill it with strips of ^-in.-thick OSB or plywood. Otherwise, the bottom part of the trim can easily be canted inward during installation. If you 11 be nailing the baseboard by hand, protect your knees with a pair of kneepads.

Right-handed people generally prefer to install baseboard counterclockwise (right to left), starting at a door. This makes it easier for righties to cut a coped joint. Lefties tend to install baseboard clockwise for the same rea­son...

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