Old main fused disconnect switch feeding other other smaller disconnect switches.... Replace?

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Cartoon1

Cartoon1

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Florida
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Electrical Engineer
Anybody seen this type of setup before? An old main fused disconnect switch rated 300A acting as a main in this electrical room, 240/120 high delta, westinghouse type box probably around 30 years old at least. What they have done overtime is continuously tap the same lugs into smaller disconnect fused switches that fed other panels..... The cables on load side and the next disconnect is not rated for 300A, so they are unprotected. Also, i see no grounding cable and the building did not have a ground rod. The owner wants to add more circuits to this building. I see a few code issues, old equipment, missing lugs, missing grounding. My opinion to provide a main enclosed breaker outside with a ground rod and replace this main old fused disconnect with a main panel and re-feed all the existing panels. Is there other cheaper solution to do this?

Thank you

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Relative common occurrence on older installations. Although the conductor protection may be proper under 240.21 tap rules, you are correct the install is ripe with violations. A main distribution panel is in order, As to M/B vs remote main disconnect that's where your engineering expertise would come in ie: available fault current, location requirement of service disconnect, etc.
 
augie47 said:
Relative common occurrence on older installations. Although the conductor protection may be proper under 240.21 tap rules, you are correct the install is ripe with violations. A main distribution panel is in order, As to M/B vs remote main disconnect that's where your engineering expertise would come in ie: available fault current, location requirement of service disconnect, etc.
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Yes, completely agree!!! I have never seen this type of setup before, but i guess it is common in older type buildings. thank you!!
 
If it wasn't for the parallel conductors in the line side lugs that are likely listed for only a single conductor, I would just install a tap box on the load side using conductors that have an ampacity that equals or exceeds the fuse rating, and run 240.21(B) taps to the other panels.
 
don_resqcapt19 said:
If it wasn't for the parallel conductors in the line side lugs that are likely listed for only a single conductor, I would just install a tap box on the load side using conductors that have an ampacity that equals or exceeds the fuse rating, and run 240.21(B) taps to the other panels.
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Yes also possible. Unfortunately the space in this room is also limited. And that disconnect fused switch is so old, I would feel better if it was replaced.
 
don_resqcapt19 said:
If it wasn't for the parallel conductors in the line side lugs that are likely listed for only a single conductor, I would just install a tap box on the load side using conductors that have an ampacity that equals or exceeds the fuse rating, and run 240.21(B) taps to the other panels.
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Could the line side lugs be replaced, or would that get into a listing issue?
 
norcal said:
Could the line side lugs be replaced, or would that get into a listing issue?
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Many things involving listing standards are not up to current listing standards on that particular switch, and the lugs would be pretty low on the list of priority I would think. I'd be much more concerned about how there is no shielding at all of the supply side of the disconnect, todayand even for the last 30 plus years they all are well shielded from incidental contact.
Cartoon1 said:
Anybody seen this type of setup before? An old main fused disconnect switch rated 300A acting as a main in this electrical room, 240/120 high delta, westinghouse type box probably around 30 years old at least. What they have done overtime is continuously tap the same lugs into smaller disconnect fused switches that fed other panels..... The cables on load side and the next disconnect is not rated for 300A, so they are unprotected. Also, i see no grounding cable and the building did not have a ground rod. The owner wants to add more circuits to this building. I see a few code issues, old equipment, missing lugs, missing grounding. My opinion to provide a main enclosed breaker outside with a ground rod and replace this main old fused disconnect with a main panel and re-feed all the existing panels. Is there other cheaper solution to do this?

Thank you
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Other than the fact they landed multiple conductors in lugs not intended for those combinations of conductors, they possibly do comply with the tap rules in 240.21. 10 foot tap rule can be 1/10th ampacity of the overcurrent protection - so if none those taps are smaller than 10 AWG that part may be ok, 10% of 300 is 30. There must also be overcurrent protection at the other end of the tap that is no higher than ampacity of the tap and of course a limit of 10 feet.

And that fused switch assembly is probably at least 50 years or older. Like I said above last 30+ years they shielded the line side components from possible incidental contact even if just a little compared to what they are like now, that one has no shielding at all.
 
kwired said:
Many things involving listing standards are not up to current listing standards on that particular switch, and the lugs would be pretty low on the list of priority I would think. I'd be much more concerned about how there is no shielding at all of the supply side of the disconnect, todayand even for the last 30 plus years they all are well shielded from incidental contact.

Other than the fact they landed multiple conductors in lugs not intended for those combinations of conductors, they possibly do comply with the tap rules in 240.21. 10 foot tap rule can be 1/10th ampacity of the overcurrent protection - so if none those taps are smaller than 10 AWG that part may be ok, 10% of 300 is 30. There must also be overcurrent protection at the other end of the tap that is no higher than ampacity of the tap and of course a limit of 10 feet.

And that fused switch assembly is probably at least 50 years or older. Like I said above last 30+ years they shielded the line side components from possible incidental contact even if just a little compared to what they are like now, that one has no shielding at all.
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They have mixed copper and aluminum conductors also.
 
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