electricblue
Senior Member
- Location
- Largo, Florida
- Occupation
- EC
What is the difference between the 2? Where is heavy required?
General duty / heavy duty
- Thread starter electricblue
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- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Assuming this refers to safety disconnect switches?
GD means it barely passes the minimum requirements to be called a disconnect switch under UL98 standards, applied in a controlled environment like a lab. Resi and light commercial use where it is unlikely to be relied upon too much, but is required by code to be there.
HD means it is designed to exceed those standards, is expected to be for industrial use, frequent operation and other adverse conditions where you never know what some fool may think it is capable of.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
When I worked for Siemens, GD switches were for the most part bought by HVAC contractors and well drillers who just wanted to meet code the cheapest way out. HD switches were bought by the ECs who had to go back out to these installations a year or two later because of defective GD switches.
Good busine$$ for the ECs though...
Good busine$$ for the ECs though...
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Is there a written standard to differentiate between the two or is it up to the manufacturer to decide? The NEC doesn't differentiate between the two.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
For the majority of manufacturers General Duty is only available in 240V max therefore its use in industrial power systems is limited.
The General duty versus Heavy duty difference is similar to that of Loadcenters versus Panelboards and Hard usage versus Extra Hard usage cords.
The General duty versus Heavy duty difference is similar to that of Loadcenters versus Panelboards and Hard usage versus Extra Hard usage cords.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
NEMA KS1-1990, or now ANSI KS1-1991, but neither is a test standard, they are design guidelines. Compliance is "voluntary", compared to UL98, which is a test standard. But UL makes no differentiation, just a minimum performance level. IIRC, the main test is 6000 operations, 600 of which must be at something like 130% of rated current. I just posted that somewhere else recently and at that time I was looking at the test procedure. Now I'm relying on my rapidly fading brain cells...
I no longer have access to a copy of the NEMA/ANSI docs, they cost about $15-20 to buy on line in PDF form.
Last edited:
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Found it (different forum)
Missed that one by a mile!
myself said:
Missed that one by a mile!
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