heavy duty vs. standard safety switches

[steve66]

Square D lists both general duty and heavy duty safety switches.

Where do you think heavy duty is needed, or do you always spec. heavy duty.

The application I have right now if for 2 outdoor residential type condensing units, and 2 indoor Fan Coil Units with about 20KW of electric heat each.

Steve

 

[kfenn]

Re: heavy duty vs. standard safety switches

Typically we spec the heavy duty for all jobs. From past experience they last longer and are better build. Also, it prevent the use of cheap equipment made by a Mom and Pop shop.

 

[templdl]

Re: heavy duty vs. standard safety switches

GD safety switches are limited to residential, commercial, and light industrial applications where HD are applied in commercial, Institutional, and industrial. But, the real differences are the ratin of the switch which defines its application. GD are rated 240v max and 250dc in larger sizes. HD switches are 600vac and 250vdc or 600vdc.
GD are limited to CL H fuse clips with optional CL R fuse adaptation with the larger 400-600A switched w/CL T or J -100ka rms amperes. GD switches have a max ampacity of 600a. HD include and additional 800a and 1200a rating w/200ka rms max w/CL L fusing.
GD switches are limited to 200HP where HD is 250 @ 240v and 500 @ 480 and 600vac.
GD switches are generally limited in NEMA 1 and 3R eclusures where HDs are available in 4,4X, 12, and 12.
Bottom line is that the GD safety switch will had an identical life as the HD if applied within its rating. So don't expect more life with the HD smitch except extra cost as both must meet identical UL testing requirements for the application.
I can not identify any documentation that would indicate that the HD switch would have a longer lift than that of a GD switch. One could only assume that the HD would have longer life because of its 600v rating.
It is not unusual that the extra cost of the word "HD" give us a warm and cuddly feeling that it is a better switch as is it mistaken to believe that a 100% rated breaker is better than an 80%.

 

[jim dungar]

Re: heavy duty vs. standard safety switches

Originally General Duty meant 250V max with limited enclosure styles and options.
Heavy Duty meant 600V max and therefore all of the "industrial" enclosure styles and options as well as "repairability". This was similar to the verbage for 250V SJ versus 600V SO cords.

In the past few years (decades?) Square D has started to add options like aux contacts and class R fuse clips to their general duty line. So for 250V applications requiring NEMA 1 or 3R enclosures there is almost no reason to use the heavy duty style.

 

[steve66]

Re: heavy duty vs. standard safety switches

Thanks. I also noticed the 250V limit on general duty. Since this is a commercial application (they won't have any spare parts, and it probably won't get switched in the next 5 years), general duty it is.

Steve

 

[kiloamp7]

Re: heavy duty vs. standard safety switches

General-Duty is probably okay for the way you describe your application.
In an industrial environment, we use 100% Heavy-Duty. Yes, costs more, but well worth it. There is no question that it is a higher quality product.

 

[charlie tuna]

Re: heavy duty vs. standard safety switches

it has been our expieriance that general duty safety switches operated close to their rated current while supplying motor loads are prone to fail!!! one major example of this is elevator equipment. first of all in elevator applications the switch is operated hundreds of times for service work, a disconnect is basically designed to be operated one hundred times in it's lifespane! consider a 100 amp disconnect with a 65 amp load --- during startups this switch would see currents almost twice it's design! and normal operating current surges in excess of 100 amps! this would occur with an empty car pulling the counter weights. now, take the same switch and raise the amperage to 80 amps. the startup current could be two and a half times larger than the design rating of the switch. and the normal operating surges could be near twice the design. even the heavy duty rated switches will fail after this type of application close to their full current rating. what we suggested was to oversize the disconnect to the next trade size in cases that were close to the full current rating of the switch.

 

[steve66]

Re: heavy duty vs. standard safety switches

Charlie:

I agree, an elevator disconnect will be operated often, and heavy duty is probably the better choice.

But our local elevator co. puts soft starts on all new elevators, so you don't have current surges that large.

Steve

 

[charlie tuna]

Re: heavy duty vs. standard safety switches

steve,
elevators was used as an example -- large motor loads apply... and yes the new elevator equipment has major improvements today--i was in one a few weeks ago and couldn't find the motors---they were built into the cable wheel assembly. twenty story building --- elevator feeder breakers were 60 amps(480v)!