Estimate projected run shrink using a rounded bend-angle chart, or enter a custom shrink rate. The angle chart also estimates spacing between bend marks.
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Conduit Shrink Formula
Variables:
- CS is the Conduit Shrink (in)
- OD is the offset distance (in)
- SPI is the shrink per inch (in/in)
To calculate Conduit Shrink, multiply the offset height by the shrink rate. The bend-angle mode uses rounded field-chart factors; use your bender’s instructions for marking.
How to Calculate Conduit Shrink?
The following steps outline how to calculate the Conduit Shrink.
- First, determine the offset distance (in).
- Next, determine the shrink per inch (in/in).
- Next, gather the formula from above = CS = OD * SPI.
- Finally, calculate the Conduit Shrink.
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
offset distance (in) = 30
shrink per inch (in/in) = 0.67 (custom rate); estimated projected shrink = 20.1 in.
FAQs
What is conduit shrink in electrical installations?
Conduit shrink is the reduction in projected reach along the original run after an offset; the conduit material itself is not shortened. Estimate it by multiplying the offset height by the shrink rate for the bending method.
Why is calculating conduit shrink important?
Calculating conduit shrink is crucial for ensuring that electrical conduit installations are precise and efficient. It helps plan bend marks and material allowance. Verify fit with the actual conduit and bender; this estimate does not ensure a perfect fit or electrical-system compliance.
Can conduit shrink calculation be used for all types of conduits?
The projected-shrink concept applies to offsets, but chart factors, bend radius and marking conventions depend on the bender and method. Check its instructions rather than assuming one chart applies to every conduit.
Are there tools available to help calculate conduit shrink?
Yes, there are various calculators and software tools available that can help in accurately calculating conduit shrink. These tools often require inputs like the offset distance and shrink per inch, similar to the manual calculation method described.
