Fused disco's still allowed?

[Coppersmith]

I'm installing a three-phase panel about 300 feet from the weatherhead. I need to install a main disconnect where the power enters the building. I'd like to use a fused disconnect instead of a circuit breaker for cost reasons. Are fused disconnects allowed in these situations under current code?

 

[ptonsparky]

I'm installing a three-phase panel about 300 feet from the weatherhead. I need to install a main disconnect where the power enters the building. I'd like to use a fused disconnect instead of a circuit breaker for cost reasons. Are fused disconnects allowed in these situations under current code?

They sure would be here. I can’t imagine why not.

eta. Make sure you ask for the neutral kit, they are not necessarily included.

 

[electrofelon]

I'm installing a three-phase panel about 300 feet from the weatherhead. I need to install a main disconnect where the power enters the building. I'd like to use a fused disconnect instead of a circuit breaker for cost reasons. Are fused disconnects allowed in these situations under current code?

Out of curiosity, how many amps and what was the cost difference? I always found there wasnt much cost difference between a fused disco and a circuit breaker enclosure, but I haven't priced say a 1000 amp (but I did install one, its big!).

 

[Coppersmith]

150 amps. I made an assumption about the three-phase circuit breaker disconnect costing a lot more. I was guessing it was $300-500. I haven't priced it. The fused disco I priced is $140 plus fuses at 3 x $40. Maybe the price difference isn't that much.

 

[electrofelon]

150 amps. I made an assumption about the three-phase circuit breaker disconnect costing a lot more. I was guessing it was $300-500. I haven't priced it. The fused disco I priced is $140 plus fuses at 3 x $40. Maybe the price difference isn't that much.

That is pretty cheap. I think cost can vary a lot depending on if its heavy duty, 600V etc. I looked up a quote I got for a fusible, 600V, heavy duty safety switch and it was $585. Non fused, heavy duty, 600V was $385. I seem to remember some discussion about general duty Vs heavy duty, like maybe general duties sometimes are not service rated? Maybe im just making that up.

FWIW IIRC a MB 208/120 200 amp loadcenter is about $450, but I dont recall priceing out a stand alone CB and enclosure.

 

[norcal]

I have heard of insurance companies sniveling about fusible switches claiming they can be overfused, but have to classify it as a rumor though, since have not experienced it personally.

 

[al hildenbrand]

I had a home inspection department that was part of the city government that attempted to outlaw fused disconnects.

This city government home inspection department was empowered by local ordinance to attest to the state of a residential property. The inspection report was required before the residential property could be listed for sale.

One of the inspector's rules to enforce (largely concerned with missing or broken box covers) required them to declare as a hazard if a finger could come in contact with an insulated conductor, or a conductive energized surface.

It took a number of years until the home inspector department extended the hazard definition to fused disconnects. I found out about it when a home owner called in great distress that the forty odd fused disconnects throughout his 1950 3 million dollar mansion had just been declared hazards and they had to be replaced/repaired before he could sell the mansion. He already had a cash buyer.

The home inspection department declared to me that all the fused disconnects had to have "dead fronts" installed to protect a person while replacing a fuse. They didn't care that most common fused safety switches don't have dead fronts.

After a back-and-forth with the State electrical AHJ, the city abandoned the fused disconnect hazard rule.

 

[Cow]

With most of our work being ag, industrial, commercial, we install a lot of fused/nonfused disconnects.

It'd be perfectly normal here.

 

[drcampbell]

... I can’t imagine why not. ...

I can imagine someone overinterpreting the rule that says all nongrounded conductors need to be interrupted simultaneously, saying that when there's a fault in one phase, a fused disconnect doesn't interrupt the other two.

 

[romex jockey]

If AIC is a concern, fused (RK5) disco's have much more AIC for the $$$

~RJ~

 

[romex jockey]

I had a home inspection department that was part of the city government that attempted to outlaw fused disconnects.

This city government home inspection department was empowered by local ordinance to attest to the state of a residential property. The inspection report was required before the residential property could be listed for sale.

One of the inspector's rules to enforce (largely concerned with missing or broken box covers) required them to declare as a hazard if a finger could come in contact with an insulated conductor, or a conductive energized surface.

It took a number of years until the home inspector department extended the hazard definition to fused disconnects. I found out about it when a home owner called in great distress that the forty odd fused disconnects throughout his 1950 3 million dollar mansion had just been declared hazards and they had to be replaced/repaired before he could sell the mansion. He already had a cash buyer.

The home inspection department declared to me that all the fused disconnects had to have "dead fronts" installed to protect a person while replacing a fuse. They didn't care that most common fused safety switches don't have dead fronts.

After a back-and-forth with the State electrical AHJ, the city abandoned the fused disconnect hazard rule.

home inspectors are the bane of my existence
:rant:
~RJ~

 

[kwired]

That is pretty cheap. I think cost can vary a lot depending on if its heavy duty, 600V etc. I looked up a quote I got for a fusible, 600V, heavy duty safety switch and it was $585. Non fused, heavy duty, 600V was $385. I seem to remember some discussion about general duty Vs heavy duty, like maybe general duties sometimes are not service rated? Maybe im just making that up.

FWIW IIRC a MB 208/120 200 amp loadcenter is about $450, but I dont recall priceing out a stand alone CB and enclosure.

Unless the load center has feed thru lugs or is capable of accepting a 200 amp branch breaker it is somewhat useless for supplying a 200 amp feeder compared to a 200 amp fused disconnect or 200 amp enclosed breaker though. Some single phase loadcenters out there with feed thru lugs, otherwise you need to get into commercial "panelboards" and the cost usually goes up with those.

I have heard of insurance companies sniveling about fusible switches claiming they can be overfused, but have to classify it as a rumor though, since have not experienced it personally.

They have some valid concern, but it is not possible to overfuse a 200 amp feeder that is supplied by a 200 amp fused disconnect, larger fuses physically won't fit. I have seen many 15/20 amp single pole breakers replaced by HO's or their non qualified expert friends with 30 amp breakers - so that logic doesn't really even work with breakers.

If AIC is a concern, fused (RK5) disco's have much more AIC for the $$$

~RJ~

yes, especially for other than 200 amp or less single phase 240 volt max.

Can I get a single breaker and enclosure for a 480 volt three phase 30 amp or less - probably, I have never seen such a thing in the wild, always a fused disconnect, usually fused disconnect for higher amperage as well. For one thing those are what is typically in stock at the supply house, the single breaker enclosure would need ordered in most cases.