PDA

View Full Version : 30A Fusible Disconnect Switch w/ Copper Pipe used as fuses



edstevn
11-03-2008, 10:08 AM
I found a General Electric 30A/240V single phase fusible disconnect switch that was used as a local service disconnect for a hot water heater. It was fed from a 30A/2P breaker out of a nearby breaker panel. I noticed it had (2) 1/2" pieces of copper pipe installed in place of fuses. I'm sure the National Electric Code book would site this as a code violation. Would they accept dummy fuses ? Do you replace the copper pipe with fuses or replace the switch with a non-fusible type?

jimbo
11-03-2008, 10:54 AM
I don't know if there is such a thing as a dummy fuse. I think it is called "copper pipe"!!

You can most likely use a non-fused disconnect, but I don't see how it would ever be legal to bypass what is intended to be a fuse.

hj
11-03-2008, 11:11 AM
There have been people here who flatten a copper tube and then put it in the meter socket, after it was pulled for nonpayment of the bill, but I am sure the utility does not consider it a "dummy meter".

Chris75
11-03-2008, 01:36 PM
Either replace with fuses or dummy fuses, but get rid of the copper pipe.

Thatguy
11-04-2008, 09:07 AM
The current to melt a piece of pipe like this was figured out on another forum. The connecting wires and everything else will melt before this does. I guess that makes it an "anti-fuse."

220/221
11-04-2008, 05:13 PM
At least they used copper.

http://i8.photobucket.com/albums/a8/JohnC1952/ee6145310bd1.jpg

Johnny C
11-04-2008, 05:31 PM
Installing copper pipe in place of proper fuses or fuse blanks is a Code violation of 110-3(B). Use of the disconnect sw with other than a product for which it was tested and listed by the testing laboratory. I will not say I haven't done this in an emergency, but it is a Code violation even though the circuit breaker ahead of the disconnect is rated for the circuit size.

Thatguy
11-05-2008, 12:07 PM
And if you want to make it into a slow blow fuse, fill the pipe with water before crimping. That way the water has to boil off before the pipe melts.
All-in-all this is a very versatile circuit element.

Just kidding.

hj
11-06-2008, 06:59 AM
If the tubing is sealed so the water cannot leak out, neither will the steam. So the water will heat to a "superheated" condition, (not steam), until something ruptures and then there will be a 'mini' explosion as the energy is disipated in a matter of microseconds.

jar546
11-06-2008, 08:26 AM
Violation NEC 2005 reference standard

110.3(B)
110.9
110.10
210.20(C)
240.6(A)
240.10
240.60(C)
240.61


Take your pick. Remove and replace with the proper sized fuses

edstevn
11-06-2008, 08:46 AM
Thanks for your help!

Thatguy
11-06-2008, 10:30 AM
If the tubing is sealed so the water cannot leak out, neither will the steam. So the water will heat to a "superheated" condition, (not steam), until something ruptures and then there will be a 'mini' explosion as the energy is disipated in a matter of microseconds.

So should I lay off all the employees I have already hired to start building these little gems?
:(
:p