horizontal mounted switch gear

Status
Not open for further replies.

billk554

Member
hello everyone,several times i have found fuses left in the bottom of horizontally mounted switch gear. i have seen one where the bottom of the switch was badly burned from a fuse coming in contact with the bottom lug of the switch and someone energized that switch. i am going to try and copy a letter i sent in order to make changes to the manufacturing process of fusing and an inclusion into the N.E.C. what i need from fellow electricians is just how common a problem this is. how many times have you opened a switch and found fuses stored in the bottom of the switch? here is the letter and if you could let me know through this forum it would be great.


To whom this should concern;


In an effort to establish a standard to eliminate one source of arc flash events, I would like to suggest that fuses manufactured with the large metal caps on the ends be revised and the metal caps be removed. Technology is available where an insulating fiber wrap can and does run the entire length of the barrel of fuses. An example of the fuse in question is the frn-r 225 fuse. This fuse style is referred to as a type h I believe. Fuses are often left in the bottom of switches. I know that they should never be left in the bottom of switches but they are. Recently while identifying loads in an eight section service I came across six switches that were energized with no loads on them. Of those six switches 2 had the fuses left in the bottom of them. We can put our heads in the sand and say the fuses need to be removed, and they do, but often they are not. On another job I had to replace a switch that, at one time had the fuses left in the bottom and the metal cap was in contact the bottom lug when somebody energized the switch. The evidence of an arc flash was overwhelming. Something should be done about this. .In an effort to address this hazard several things need to be done.
1. Establish a standard in the N.E.C. for horizontal switch gear where no bladed fuse with metal end caps be used. Only fuses wrapped with the fiber insulation material should be installed.
2. Set a time stamp where as by a certain date all the unapproved fuses should be removed and replaced with the new style fuse. This would give companies and maintenance personnel an opportunity to open every switch in their distribution and make certain any and all old fusing, in use or stored in the bottom of switch gear, has been removed.
3. Have fuse manufacturers develop fuses with the insulating wrap from top to bottom. The metal cap fuses are still o k for vertical stand alone disconnects.. those fuses should carry a warning ?not approved for horizontal switch gear?
4. Have manufacturers of switch gear interlock the operating handles so the switch would not be able to energize unless fuses are installed. Once the fuse is installed into the switch there could be an insulated fiber round the blade of the fuse would push down and the switch would be able to energize. This would have to be done on only 2 legs to allow for single phase loads. Those legs would have to be labeled ?single phase circuits here?
5. Enlist the help of electrical inspectors nationwide to inspect not only the loads being installed but to look inside several switches while in the plant to observe what is being used and what isn?t, and be sure no fuses are left in abandoned switches.
I have thought about this problem for a long time and I know that something has to be done. Doing this is an enormous undertaking and will take years to accomplish. In the end people will be safer. Lives will be saved. I think with the constant turnover of maintenance personnel, the age of most of our facilities, the on again off again projects in manufacturing plants across the country, people in charge of the maintenance of switch gear may not know what is behind that switch door.
In manufacturing plants where thermal imaging is routine, arc flash analysis are being completed, qualified maintenance personnel are in place and doing what they are trained to do many of the hazards disappear but many of us don?t work at those places.

In an effort to establish this standard, I have written the N.F.P.A. and received instructions on how to develop interest in setting this new standard in place. I am sending this letter to
1. National Electrical Manufacturers Association
1300 North 17th Street
Suite 1752
Rosslyn, Virginia 22209
2. A.N.S.I.
1819 L Street, NW
(between 18th and
19th Streets), 6th floor
Washington, DC 20036
3. Cooper Bussmann
114 Old State Road
Ellisville, MO 63021-5942
4. International association of electrical inspectors
5. 901 Waterfall Way, Ste. 602
Richardson, TX 75080-7702

I thank you for your time in reading this and hope you could take the time to respond.
 

wireguru

Senior Member
someone could just as easily leave a wrench in there. There is no need to legislate a different type of fuse. The effort should be focused toward enforcing the "dont leave things inside a switch"
 
Status
Not open for further replies.
Top