Build it and they will come
You run power 375' from a source, some one at some time will want to tap onto it. Not required to be taken into account, not desirable if you are bidding on price only, but just an observation based on experience.
Conductor sizing 375 foot run
- Thread starter hotblueelectric
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Build it and they will come
You run power 375' from a source, some one at some time will want to tap onto it. Not required to be taken into account, not desirable if you are bidding on price only, but just an observation based on experience.
I'd still consider the transformer option, upsized from my earlier numbers for additional power.Build it and they will come
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
On the original post: I agree with others that the simple answer to your original question is the simple plan of just using 4 conductors, all the same size, to supply two 120V circuits as an MWBC.
On the tangent suggestion of using a transformer to supply these loads: I agree with Smart$ on the concept of using a higher voltage load at this distance. For the same power, the higher the load voltage, the lower the current, and thus the smaller conductor needed for the same % voltage drop. Before considering a transformer, which is an extra component that will burn power continuously, I would look into using 230V motors rather then 115V motors. I wouldn't want to step 240V down to 120V in order to run a motor when the motor itself is essentially a transformer.
On the tangent discussion of 250.122(B) : I belive that the basic reason for having this rule is correct, but I believe that the rule as worded leads to confusion and paradox. IMHO the rule should be written as a performance requirement, and then the proportional upsizing provided as one of the permitted methods for achieving that performance requirement.
As currently written, the application of 250.122(B) depends upon sizing of conductors for voltage drop...but sizing of conductors for voltage drop is not itself mandated, and so this rule rewards bad design. In the paradoxical example given (where a set of conductors, without an upsized EGC, needed on a 20A circuit for voltage drop reasons, is 'legal' on a 60A breaker but a violation on a 20A breaker), the voltage drop of the 60A circuit would be excessive, and the intent of 250.122(B) would not be met. But the _words_ of 250.122(B) would be met.
The performance requirement might be 'bolted fault current sufficient to insure instantaneous trip' or 'voltage rise of EGC bonded metal at the fault of less than...', or something similar.
I would specifically permit the use of ground fault protection to substitute for a larger EGC, because much lower faults to the EGC will trip ground fault protection.
I would also change the proportional increase requirement to include the normal tolerances found in AWG size specifications, so that you could simply increase the EGC by the same number of wire gauges as the circuit conductors, and not have rounding issues bump you to the next larger wire gauge.
-Jon
On the tangent suggestion of using a transformer to supply these loads: I agree with Smart$ on the concept of using a higher voltage load at this distance. For the same power, the higher the load voltage, the lower the current, and thus the smaller conductor needed for the same % voltage drop. Before considering a transformer, which is an extra component that will burn power continuously, I would look into using 230V motors rather then 115V motors. I wouldn't want to step 240V down to 120V in order to run a motor when the motor itself is essentially a transformer.
On the tangent discussion of 250.122(B) : I belive that the basic reason for having this rule is correct, but I believe that the rule as worded leads to confusion and paradox. IMHO the rule should be written as a performance requirement, and then the proportional upsizing provided as one of the permitted methods for achieving that performance requirement.
As currently written, the application of 250.122(B) depends upon sizing of conductors for voltage drop...but sizing of conductors for voltage drop is not itself mandated, and so this rule rewards bad design. In the paradoxical example given (where a set of conductors, without an upsized EGC, needed on a 20A circuit for voltage drop reasons, is 'legal' on a 60A breaker but a violation on a 20A breaker), the voltage drop of the 60A circuit would be excessive, and the intent of 250.122(B) would not be met. But the _words_ of 250.122(B) would be met.
The performance requirement might be 'bolted fault current sufficient to insure instantaneous trip' or 'voltage rise of EGC bonded metal at the fault of less than...', or something similar.
I would specifically permit the use of ground fault protection to substitute for a larger EGC, because much lower faults to the EGC will trip ground fault protection.
I would also change the proportional increase requirement to include the normal tolerances found in AWG size specifications, so that you could simply increase the EGC by the same number of wire gauges as the circuit conductors, and not have rounding issues bump you to the next larger wire gauge.
-Jon
hotblueelectric
Member
- Location
- Dallas Texas
The circuits are strictly dedicated for 2 gate openers. Nothing else. I've decided to run all #6's for both line circuits, and #6's for the neutral and ECG. This will limit my voltage drop to 2.35%. Thank you all for your feedback.
My question, is how do you intend to terminate #4 wire at a 20A breaker?
Fulthrotl
~Autocorrect is My Worst Enema.~
- Occupation
- E
neutral and ground are both undersized, i believe.
i just did one of these last month.. about the same length.
the gate opener came in two configurations... one for an
800# gate, and another for a 2,000# gate... the openers
were identical in appearance, and had two 1/2 hp motors.....
the light duty unit used one motor to open, and one motor
to close the gate, and the heavy duty unit used both motors
to open and close the gate... check your cut sheets on your
opener. i bid it for the 800# unit, and the gate guy thought
the 2,000# unit would be better..... oh, well.....
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