480 volt 400 amp service disconnect fuses or breaker

Status
Not open for further replies.
F

FREEBALL

Senior Member
Location
york pa usa
Can anyone with an unbiased opinion give me an answer if one or the other are better. I know besides the fact a breaker can be reset but is there any other reason one is better than the other. I searched and found fuse sites stating their claim and breaker manufactures the like. Any info woud be appreciated. Job is a 600 amp service split into a 200 amp and 400 amp service disconnect
 
FREEBALL said:
Can anyone with an unbiased opinion give me an answer if one or the other are better. I know besides the fact a breaker can be reset but is there any other reason one is better than the other. I searched and found fuse sites stating their claim and breaker manufactures the like. Any info woud be appreciated. Job is a 600 amp service split into a 200 amp and 400 amp service disconnect
Click to expand...

Clearly there is no one 'best' device. Breakers have been used for more than 90 years.

Except for true mis-applications it is strictly a personal choice.
I know some people make their choice based on installation issues, such as physical size or the ability to bottom feed a breaker.
 
If you have loads which could be harmed by single phasing, a breaker will open all ungrounded conductors at once.
Unless supplemented by additional devices, fuses cannot do that.

mobile
 
GoldDigger said:
If you have loads which could be harmed by single phasing, a breaker will open all ungrounded conductors at once.
Unless supplemented by additional devices, fuses cannot do that.

mobile
Click to expand...

Well I didn't want to add that just to see response but yes there are 2 50 hp 460v motors along with a few smaller three phase motors. I do not know of the sensing equipment of the equipment, its a package system on the 2 50 hp motors, but do you think they would have that type of protection to guard against single phasing ?
 
FREEBALL said:
Well I didn't want to add that just to see response but yes there are 2 50 hp 460v motors along with a few smaller three phase motors. I do not know of the sensing equipment of the equipment, its a package system on the 2 50 hp motors, but do you think they would have that type of protection to guard against single phasing ?
Click to expand...

The existing 200 amp that I am refeeding is fused from old service, so I am not concerned for that but the 400 amp is going to feed the new equipment, i.e. 50 hp motors.
 
GoldDigger said:
I like breakers unless you have a problem meeting the AIC requirement.
Click to expand...


I got ya Im a square D man but the breaker and enclosure is so darn expensive compared to their fused disconnect. I just wanted an opinion, or first hand experience on one or the other. I am sure the overloads will suffice on the starter. thanx for the insight.
 
Not sure of the specific arrangement, but a MLO panel with multiple breakers may be cost competitive option. The breakers for you motors would be your service disconnects. Of course you could only have 5 since you already have 1
 
Most of what I do involves 3 phase motors, so I have had a personal bias against fused disconnects for years, I've seen a LOT of damaged motors. Yes, people SHOULD put in phase loss protection, but it adds money again plus there are problems with that too. Cheap voltage based phase monitors can be "fooled" by motors that are still spinning after a fuse blows, because they essentially become "rotary phase converters" and add back the 3rd phase voltage, so the relay can actually allow the very thing they are bought to protect against. More expensive voltage based and current base phase monitors are better, but cost more and make the CBs look better again compared to the fused disconnects.

The thing that is changing my mind more so now is that I have taken to only promoting the use of solid state OL relays, because most of them just build in the current based phase loss protection anyway.
 
electrofelon said:
Not sure of the specific arrangement, but a MLO panel with multiple breakers may be cost competitive option. The breakers for you motors would be your service disconnects. Of course you could only have 5 since you already have 1
Click to expand...

I agree

Another way would be to use two 200 amp main breaker panels. Almost always less expensive.
 
I saw a demo at the Bussman facility in St. Louis back in the early 80's. Of course, they were trying to show the superiority of fuses vs. breakers. They had 2 long, fairly large (maybe 250 MCM) conductors laying on the floor. They would short the ends of the wires when protected by breaker and the fault current created enough magnetic field to cause the wires to jump violently. They would then repeat the test using their fuses for protection and the wires barely moved. I'm not sure how valid this is especially from a quantitative standpoint, but it was fun to watch.

Regardless, as others have stated, breakers are preferable if single phasing is a concern.


Sent from my iPad using Tapatalk
 
iwire said:
I agree

Another way would be to use two 200 amp main breaker panels. Almost always less expensive.
Click to expand...
Often true for "loadcenters".

Go to 480 or 600 volt rated panels and breakers - you need to get a quote for each method, and factor in labor and other materials differences.

Those expensive breakers for things like I line panels are usually pretty cheap if you purchase the entire job on one quote compared to buying each breaker individually on separate orders.
 
Status
Not open for further replies.
Top