3/4" copper water pipe to replace fuse

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innergee

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Recently I had to argue with an HVAC tech regarding the placement of pipe or EMT in a fusible disconnect. He said that it was a "72 hour shunt"???? I know and would never put anything but a fuse in place of a fuse. Either way the end result was the package HVAC unit the disconnect was protecting locked up. Both fuses blew and since the pipe didn't "blow" it bypassed the eatery's 400A main and blew the building's 1000A main breaker. No tripped breakers. How many electricians or "techs" do this? And is it at all anywhere acceptable?
 
innergee said:
How many electricians or "techs" do this?
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Professionals do not do that.

And is it at all anywhere acceptable?
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No, if you have a fused disconnect in a place that already had proper over current protection and you did not need or want fuses for the disconnect you could buy 'Dummy fuses' to install but under no circumstance can you just stick a piece of plumbing pipe in the fuse holders.
 
chris kennedy said:
I've never seen these.
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Here you go, probably a handy item for corner grounded delta systems.

Neutral_photo1.jpg



Dummy Fuse
 
Is is not acceptable anywhere that I know of there is too much liability involved for me when someone knowingly substitutes something that is wrong and causes problems. In my opinion this tech should be arrested for jeopardizing everyone in the buildings life because of his actions. Thank god the main blew before a fire started. Inconveniencing everyone else in the building.
 
I've seen this done too. Personally I wouldn't do it because I like to sleep at night. Some people obviously don't or don't care. :rolleyes:
 
innergee said:
How many electricians or "techs" do this? And is it at all anywhere acceptable?
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My only comment was, I hope his (or his employer's) liability insurance is paid up. That sounds like a clear-cut claim against their policy, to me. If for nothing else, at least for business down-time and whatever after hours service and testing was involved to get things up and running again. The locked up compressor may or may not have been a result of the lack of proper overcurrent protection, but I'd rather say it was inevitable, without regard to the overcurrent protection status.
 
JohnJ0906 said:
240.22

As Iwire posted, handy for a corner grounded Delta system.
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Also handy for using or re-using a 3 pole disconnect for a single phase circuit. It turns that one pole into a switched neutral.
 
I have seen these used several times in older homes with a 60 or 100 amp 120/240 service with a 3 pole fused disconnect that had the neutral fused. Instead of pulling a new neutral or lugging it together, these busses could be used to complete the neutral (that should not be fused). If you blow the neutral fuse you series the loads in line1 with the loads in line 2. HUH - why does the vacuum slow down when I turn on the lights?

Obviously it' would be time to get a new service and probably replace the knob and tube, but sometimes it's hard to convince the home owner when a little piece of "pipe" will make the problem go away? Or least they think?
 
innergee said:
Both fuses blew and since the pipe didn't "blow" it bypassed the eatery's 400A main and blew the building's 1000A main breaker.
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Even if the unit had fuses - depending on the trip curve of both the main and anything in between it and the fuses - the same result could have happened.

Or it could have blown the fuses AND still tripped the main....
 
I have seen these used in some old homes with a 60 or 100 amp 120/240 service, that had a 3 pole fused disconnect with the center used for the neutral. If you blow the neutral fuse you wind up putting the loads in line1 in series with the loads in line2. HUH - why does the vacuum slow down when I turn the lights on? Better to rewire the neutral, but I suspect that in that case, that would be an area where these busses could be used.

Probably best to put in a new service and replace the knob and tube while you are at it?
 
innergee said:
Recently I had to argue with an HVAC tech regarding the placement of pipe or EMT in a fusible disconnect. He said that it was a "72 hour shunt"???? I know and would never put anything but a fuse in place of a fuse. Either way the end result was the package HVAC unit the disconnect was protecting locked up. Both fuses blew and since the pipe didn't "blow" it bypassed the eatery's 400A main and blew the building's 1000A main breaker. No tripped breakers. How many electricians or "techs" do this? And is it at all anywhere acceptable?
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I saw the same thing a few months ago in a buss duct switch. The owner of the book factory told me "the pesky fuses kept blowing" I told him that if he wanted me to be "his guy" then he would have to let me replace it.
 
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