hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
I have 200A fused disconnect fed from 225A feeder breaker. Is their any NEC code section 2017 that says this cannot be done?
225A fused disconnect
- Thread starter hhsting
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hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
No. I have 200A fused disconnect fed from 225A feeder breaker.
Size of fuse in disconnect is 175A
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
Issue: breaker size feeding is 225A how does it protect the 200A fused disconnect?
kwired
Electron manager
- Location
- NE Nebraska
is it fed with 225 amp conductor or if not does it comply with tap rules?
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
Yes it fed with 4/0awg copper conductors
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I don't see a problem
What protects your service entrance equipment from the power available from the utility company?
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
Why not? Whats protecting the 200A fused disconnect?
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
The fused disconnect protects itself. That's why it has fuses.
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
Right. Just like the fuses in this disconnect will protect it.
The 225A circuit breaker is protecting the 200A fused disconnect. The 175A fuses are protecting everything downstream of that.The inside overcurrent protection?
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hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
How? 225A breaker protects 200A fused disco? Its 200A breaker is 225A???
hhsting
Senior Member
- Location
- Glen bunie, md, us
- Occupation
- Junior plan reviewer
Is there any code section for that?
???? Can you clarify what you have? Your numbers have changed a few times now. But either way... if the disconnect is rated for 225A but is furnished with 175A fuses, you don't have an issue.
kwired
Electron manager
- Location
- NE Nebraska
There is that for general applications.
For non fused switches sometimes you have horsepower rating that high enough you can end up using switch for motor disconnect where the branch circuit device is higher rating than the switch.
I've installed a lot of 60 amp non fused disconnects for 25 HP 480 volt motors though the circuit breaker supplying this is 70 amps as well as 30 amp non fused switch for 20 HP though the breaker is 60 amp.
The switch itself might be able to handle more current than the largest fuse the fuseholder can handle but switches don't really require any specific ocpd they just need to be able to handle switching the load that is connected.
kwired
Electron manager
- Location
- NE Nebraska
Have you ever seen a 200 amp tap made from a 400, 600... 1200 amp feeder?
A 200 amp fused switch or breaker would be at the end of the tap.
Same fused switch often could also be a service disconnecting means and for the most part can have no real OCPD ahead of it.
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