Question 1

What are the main types of conduit and when do I use each?

Accepted Answer

Rigid metal conduit (RMC) is steel tubing, very strong, protects wires in harsh outdoor and industrial environments, but heavy and expensive. Intermediate metal conduit (IMC) is lighter than RMC, used indoors in most commercial and industrial work. Electrical metallic tubing (EMT, also called 'thin-wall') is the lightest metal, used indoors in most residential and light commercial, cheaper and easier to bend. PVC plastic conduit is lightweight and corrosion-resistant, used outdoors and in wet areas, but cannot be bent by hand (requires heat or factory sweeps). Choose based on environment (wet/dry), location (above/below ground), and code requirements.

Question 2

How do I calculate a 90-degree bend offset using geometry?

Accepted Answer

An offset is a pair of bends that routes conduit around an obstacle. If the obstacle is 4 inches high and you want a 45-degree angle, the horizontal distance is 4 ÷ sin(45°) = 5.66 inches. The multiplier for 45 degrees is 1.41, so bend distance = 4 × 1.41 = 5.65 inches. For 30 degrees, the multiplier is 2.0; for 60 degrees, it is 0.58. Most electricians memorize the common multipliers (30°, 45°, 60°) and look up or calculate the rest. A simple formula: horizontal distance ÷ multiplier = bend distance.

Question 3

What is bend deduction and why do I measure from the back of the conduit?

Accepted Answer

When you bend conduit, the material stretches at the outside of the bend (radius) and compresses at the inside (heel). The 'back' (outer radius) is longer than the centerline. Bend deduction is the amount of extra length that moves through the bender during the bend. For a simple 90-degree bend on a hand bender, the deduction is roughly 6 inches for 1-inch conduit, less for smaller sizes. Always measure from the back or heel of the bender, not the front, to account for deduction. Failing to account for bend deduction results in conduit runs that are too long or too short.

Question 4

How do I bend a 90-degree bend on a hand bender without kinking?

Accepted Answer

Fill the conduit with sand to prevent kinking (the sand supports the inside). Mark the 90-degree point on the conduit. Place the conduit in the hand bender with the mark aligned with the arrow or reference line on the bender. Apply steady downward pressure with your foot on the bender arm, bending slowly to 90 degrees. Watch the angle and stop when the bender sides are parallel. Do not overshoot past 90 degrees. For tight spaces, use a segment bender (hydraulic, more control). Always wear safety glasses and clear the work area.

Question 5

What is the NEC rule for conduit fill and how do I check it?

Accepted Answer

The NEC requires that conductors in conduit do not exceed 40% of the conduit cross-sectional area. For example, a ½-inch EMT has 0.126 square inches of area; 40% fill is 0.050 square inches. Three 12 AWG wires (0.0133 each) = 0.040 total, leaving room for the fourth. Fill rules are in NEC Table 4, and exceeding fill causes overheating and difficulty pulling wires. Online calculators exist, but knowing the rule helps you avoid mistakes on the job.

Question 6

How do I secure conduit to the structure properly?

Accepted Answer

Conduit must be secured to the building structure using straps, clamps, or hangers rated for the conduit type and load. The NEC requires support within 3 feet of every junction box, outlet, or fitting, and then every 3 feet thereafter (some codes say every 2 feet for rigid metal conduit). For vertical runs, support is required at the bottom and then every 10 feet. Fasteners must be rated for the environment (stainless steel in wet areas, concrete anchors on concrete, etc.). Over-tightening a strap can crush EMT; tighten just enough to prevent sag.

Question 7

What safety precautions should I take when using a mechanical conduit bender?

Accepted Answer

Mechanical benders (hydraulic or electric) are powerful and can crush fingers or hands. Always ensure the conduit is centered in the bender before activating power. Keep hands, feet, and hair clear of the bending head. Wear safety glasses to protect from flying deburrs or metal. Never reach into the bender while it is operating. Follow the manufacturer's lockout/tagout procedure if you need to maintain or clear a jam. A mechanical bender is faster and more consistent than hand bending, but demands respect and training.

ภูมิภาค	เจ้าหน้าที่จูเนียร์	ระดับกลาง	เจ้าหน้าที่อาวุโส
USA	$30k	$48k	$70k
UK	£20k	£32k	£48k
EU	€23k	€38k	€56k
CANADA	C$36k	C$56k	C$82k

ภูมิภาค	เจ้าหน้าที่จูเนียร์	ระดับกลาง	เจ้าหน้าที่อาวุโส
USA	$30k	$48k	$70k
UK	£20k	£32k	£48k
EU	€23k	€38k	€56k
CANADA	C$36k	C$56k	C$82k

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