Are main breakers always better than fusible panelboards?

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Murloc

Murloc

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At a site I'm looking at there is a Fusible Panelboard - Eaton PRL4F installed https://www.eaton.com/content/dam/e...lboard-prl4f-fuse-design-guide-dg014004en.pdf

  • support mentions the model is rather old, so there is worry that replacement parts would be difficult to find in the future.
I'm thinking of installing one of two options

  1. Main circuit breaker panelboard using, JD breakers
    1. https://www.se.com/ca/en/product/HC...r-42in-w-x-59in-h-x-9-5in-d-cu-bus-w-neutral/
  2. Fusible panelboard - Bussman QSCP12
    1. https://www.eaton.com/content/dam/e...es/data-sheets/bus-ele-ds-1171-qscp-1200a.pdf
For the most part, people say breakers are better since you can trip them more often without problems. Some say fuses are better since they are weaker and provide more protection.




Are there some other factors I'm missing? Thanks
 
Really comes down to let through energy potential and what is acceptable for your application. And same equipment can have different performance on different sources along with consideration of conductor size, type and length.

One thing that is common at least with some electronics they often want special "fast acting" fuses on the item say a VFD. All that fuse really does is limit how spectacular a failure event may be, the item being protected is still damaged. You do want to contain that damage to what failed however and not let it progress to other items.
 
Fuses may be better for coordination and if the AFC is WAY up there. If Series ratings are important, I think you will find there are less series ratings from fuses to circuit breakers.

I would probably go with circuit breakers unless it was some special application or had unusual conditions.
 
Murloc said:
  • support mentions the model is rather old, so there is worry that replacement parts would be difficult to find in the future.
Click to expand...
What is the reason that no major manufacturer has fusible distribution equipment designs that are not decades old?

Is it because there's not a large enough market to justify new product development?
Maybe it is because the present designs are simple enough they are timeless and do not need to be improved?
Have the improvements in molded case circuit breakers met some of the advantages that fuses offered, like selectivity and fault current handling, while offering easily implemented functionality like ground fault and shunt tripping.

From what I have seen over the past 30 years the only major fusible equipment changes have been in the branch device panel boards offered by fuse manufactures
 
The problem with fuses is that when they blow at 3 am on Sunday morning, where are you going to go to get a replacement 2000 A class L fuse?

You can say spare parts room, but over time the spare parts get used and often not replaced.
 
Murloc said:
For the most part, people say breakers are better since you can trip them more often without problems. Some say fuses are better since they are weaker and provide more protection.
Click to expand...
In an all-other-things-being-equal discussion, I consider fuses to be more reliable protection than breakers, because it's almost impossible for a fuse to fail to open when it should.
 
LarryFine said:
In an all-other-things-being-equal discussion, I consider fuses to be more reliable protection than breakers, because it's almost impossible for a fuse to fail to open when it should.
Click to expand...
That may be true for the individual overcurrent element, but it is not always the case for the switch blades. It is not unusual to have situations where a single phasing condition cannot easily be remedied because the 3-phase blade mechanism failed to open.
 
jim dungar said:
That may be true for the individual overcurrent element, but it is not always the case for the switch blades. It is not unusual to have situations where a single phasing condition cannot easily be remedied because the 3-phase blade mechanism failed to open.
Click to expand...
Thus my disclaimer.
 
jim dungar said:
That may be true for the individual overcurrent element, but it is not always the case for the switch blades. It is not unusual to have situations where a single phasing condition cannot easily be remedied because the 3-phase blade mechanism failed to open.
Click to expand...
Been there, done that, got the T-shirt and the hat.

Had a corn syrup factory where the main plant engineer was a “fuses, no breakers” guy. We did a PM call in advance of a scheduled shutdown that included an IR scan on all of the fused disconnects under load, because they had a couple of spectacular failures. Most of the MCCs and switchboards had been installed in the 70s or 80s and at least 50% of the disconnects showed troubling signs of the blades over heating. So in preparation for the shutdown, we ordered replacement disconnect mechanisms. Many of them were so obsolete that there were no replacements available, which meant either replacing the entire MCC bucket with new or a major rework in the field when they were fixed mounted units.
 
Jraef said:
Been there, done that, got the T-shirt and the hat.

Had a corn syrup factory where the main plant engineer was a “fuses, no breakers” guy. We did a PM call in advance of a scheduled shutdown that included an IR scan on all of the fused disconnects under load, because they had a couple of spectacular failures. Most of the MCCs and switchboards had been installed in the 70s or 80s and at least 50% of the disconnects showed troubling signs of the blades over heating. So in preparation for the shutdown, we ordered replacement disconnect mechanisms. Many of them were so obsolete that there were no replacements available, which meant either replacing the entire MCC bucket with new or a major rework in the field when they were fixed mounted units.
Click to expand...
ahh so obsolescence is a factor to consider. Any chance you remember what brand it was so I know to avoid using it? I was going to replace an Eaton PRL4F in kind, but the support said it was obsolete and gave me a guideline on obsolete items and then a couple days later told me it wasn't and was just an old design.
 
Murloc said:
ahh so obsolescence is a factor to consider. Any chance you remember what brand it was so I know to avoid using it? I was going to replace an Eaton PRL4F in kind, but the support said it was obsolete and gave me a guideline on obsolete items and then a couple days later told me it wasn't and was just an old design.
Click to expand...

That may possibly mean they aren't necessarily producing new units, but can still make replacement components for that particular product line as needed. Which also would likely mean there may not be certain parts in stock and ready to ship so you will need to wait for them to be manufactured.
 
Murloc said:
At a site I'm looking at there is a Fusible Panelboard - Eaton PRL4F installed https://www.eaton.com/content/dam/e...lboard-prl4f-fuse-design-guide-dg014004en.pdf

  • support mentions the model is rather old, so there is worry that replacement parts would be difficult to find in the future.
I'm thinking of installing one of two options

  1. Main circuit breaker panelboard using, JD breakers
    1. https://www.se.com/ca/en/product/HC...r-42in-w-x-59in-h-x-9-5in-d-cu-bus-w-neutral/
  2. Fusible panelboard - Bussman QSCP12
    1. https://www.eaton.com/content/dam/e...es/data-sheets/bus-ele-ds-1171-qscp-1200a.pdf
For the most part, people say breakers are better since you can trip them more often without problems. Some say fuses are better since they are weaker and provide more protection.




Are there some other factors I'm missing? Thanks
Click to expand...
What if you installed arc fault GFCI combo breakers? Say in an Eaton Pannel But preferably a Square D
 
Murloc said:
ahh so obsolescence is a factor to consider. Any chance you remember what brand it was so I know to avoid using it? I was going to replace an Eaton PRL4F in kind, but the support said it was obsolete and gave me a guideline on obsolete items and then a couple days later told me it wasn't and was just an old design.
Click to expand...
It was a mash up of several brands. They had old Westinghouse switchboards, some Siemens, some Square D separate fused safety switches on the wall that were bad, a Furnas MCC and a lot of upgraded older Allen Bradley MCCs. Getting parts from Siemens for the old Furnas MCC was a nightmare. A-B has changed their fused disconnect switch design since the 80s and on some of the bigger ones, parts were technically available but really hard to get in a reasonable time frame (this was years before COVID). On the smaller ones we just bought new buckets. A-B has not changed their bus and structure design since the 70s, so new buckets still plug right in. It was a lot less labor to just do that rather that disassemble old buckets in the field to replace just the switches. The plant had changed over to Ethernet control of their MCCs a while ago, so there was no control wiring to deal with. Made it really simple.
 
Jraef said:
It was a mash up of several brands. They had old Westinghouse switchboards, some Siemens, some Square D separate fused safety switches on the wall that were bad, a Furnas MCC and a lot of upgraded older Allen Bradley MCCs. Getting parts from Siemens for the old Furnas MCC was a nightmare. A-B has changed their fused disconnect switch design since the 80s and on some of the bigger ones, parts were technically available but really hard to get in a reasonable time frame (this was years before COVID). On the smaller ones we just bought new buckets. A-B has not changed their bus and structure design since the 70s, so new buckets still plug right in. It was a lot less labor to just do that rather that disassemble old buckets in the field to replace just the switches. The plant had changed over to Ethernet control of their MCCs a while ago, so there was no control wiring to deal with. Made it really simple.
Click to expand...
ahh so you didn't replace the bus, but eventually found new fused switches that can be installed on the old bus
 
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