Wire size based on ampacity

[kody916]

Greetings

kindly see the attached.its shows a daisy chain connection for the
three motors.the motor ampacity and wire size based on the ampacities
is written on the attachment.

let me know if the correct ampacity is being used for sizing the wires.


Thanks

 

[Smart $]

Unless you left a lot of information out of the drawing, it has major problems.

1) tap conductor rules
2) motor feeder ground fault and short circuit protection
3) motor circuit ground fault and short circuit protection
4) motor overload protection

...to start with.

 

[GoldDigger]

Unless you left a lot of information out of the drawing, it has major problems.

1) tap conductor rules
2) motor feeder ground fault and short circuit protection
3) motor circuit ground fault and short circuit protection
4) motor overload protection

...to start with.

kody916: We also need to know whether the 30A figure you show for each motor is the Minimum Circuit Ampacity or some other figure and also what Maximum OCPD size is listed for each motor.

There are detailed rules on motor groups (on a single branch circuit), including 430.24, 430.53 and 430.87, that would have to be followed (addressing factors 2, 3 and 4), even if you did not change the conductor size along the way in violation of the tap rules.

 

[petersonra]

Unless you left a lot of information out of the drawing, it has major problems.

1) tap conductor rules
2) motor feeder ground fault and short circuit protection
3) motor circuit ground fault and short circuit protection
4) motor overload protection

...to start with.

I agree. depending on what the sketch actually means. potentially it could be correct if all three sets of wires were based on 30A and wired direct to the CB.

 

[petersonra]

I agree. depending on what the sketch actually means. potentially it could be correct if all three sets of wires were based on 30A and wired direct to the CB.

it could also potentially be Ok if the 30A wires going to the 3rd motor were wired to the first motor instead of the second.

 

[Jraef]

Greetings

kindly see the attached.its shows a daisy chain connection for the
three motors.the motor ampacity and wire size based on the ampacities
is written on the attachment.

let me know if the correct ampacity is being used for sizing the wires.


Thanks

If the circuit you are proposing is EXACTLY as shown in that sketch, it cannot be done that way at all, so discussing the ampacity of the wires is pointless.

Each motor circuit must have:
A) Branch short circuit and ground fault protection, sized per article 430.52 for each motor circuit. If the one breaker manages to fit the rules for any one individual motor and yet still allow all three to start, you might get away with it, but at that size, I seriously doubt it.
B) Motor thermal overload protection, sized per 430.31 for each individual motor. That then also implies some way to disconnect power to the motors. You can use one upstream device, but it will of course disconnect all devices connected to it. The motors might have internal thermal overload protection built-in, but at that size and 3 phase, not likely.

 

[Smart $]

... The motors might have internal thermal overload protection built-in, but at that size and 3 phase, not likely.

Well to be completely accurate, they may have a built-in thermal overload switch... but usually have separate terminals for wiring into the control circuit.

 

[texie]

Greetings

kindly see the attached.its shows a daisy chain connection for the
three motors.the motor ampacity and wire size based on the ampacities
is written on the attachment.

let me know if the correct ampacity is being used for sizing the wires.


Thanks

As others have said, this is not even close to compliant as shown. Much more detail is also required.
Sounds like maybe you need some help with Art. 430 rules. Are you a licensed electrician?
While I've seen setups like this done by DIY folks and farmers and it will function, but not in a safe and code compliant manner.