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Old 06-11-2019, 09:06 PM   #1
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Default Motor Ciruit Breaker Switch

Hello,

I have a connector with 480VAC and I need to connect 2 motors (one at a time with the selector switch) FLA 6.5 and 2.85. Obviously these require different circuit protection.

Is there a rule in the NFPA70 (replacement of the NEC), which says we cannot use a control relay to select the appropriate CB or the motor?

CB1, CB2 - circuit breakers
M1, M2 - motors

---||---CB1---(M1)--
---|\|---CB2---(M2)--
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Old 06-11-2019, 10:35 PM   #2
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Here the thing .,, are you legit electrician or maintenance personal ?

If you are electrician then please fill the profile fourm.

the reason why I asked to fill it out because the answer will varies a little depending on which side of national border line is. ( CEC or NEC )
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Old 06-12-2019, 12:36 AM   #3
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Originally Posted by frenchelectrican View Post
Here the thing .,, are you legit electrician or maintenance personal ?

If you are electrician then please fill the profile fourm.

the reason why I asked to fill it out because the answer will varies a little depending on which side of national border line is. ( CEC or NEC )
As per the original posting, the question is per NFPA70 -> NEC
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Old 06-12-2019, 12:45 AM   #4
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Why do both motors have to use the same "connector?"


Why not two "connectors" with a selector switch to energize one or the other?
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Old 06-12-2019, 01:26 AM   #5
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Why do both motors have to use the same "connector?"


Why not two "connectors" with a selector switch to energize one or the other?
The motor connectors are identical and have to stay this way -> constraint. To save on components, I'm questioning whether its valid/legal to have one circuit with a switch for the CB's for different motors.
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Old 06-12-2019, 06:17 AM   #6
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As long as the circuit is protected by an appropriate breaker or fuse, then it can feed other breakers downstream no problem.
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Old 06-12-2019, 06:18 AM   #7
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circuit breakers don't protect the motor they protect the wire and fault clearing.

The question makes no sense to me as its lacking details.

480 single phase?
internal thermal protection motors?
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Old 06-12-2019, 10:09 AM   #8
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Quote:
Originally Posted by gpop View Post
circuit breakers don't protect the motor they protect the wire and fault clearing.

The question makes no sense to me as its lacking details.

480 single phase?
internal thermal protection motors?
Circuit breakers protect device, that's why you choose them by the FLA.
Fuses protect the wires, that's why you choose them based on the wire size.

The topic is closed as I've gotten my answer elsewhere.

Thank you, all.
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Old 06-12-2019, 10:15 AM   #9
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Quote:
Originally Posted by alexbeatle View Post
Circuit breakers protect device, that's why you choose them by the FLA.
Fuses protect the wires, that's why you choose them based on the wire size.
That's just silly.

Quote:
The topic is closed as I've gotten my answer elsewhere.

Thank you, all.
I'll let you know when the topic is closed!
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Old 06-12-2019, 10:20 AM   #10
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Quote:
Originally Posted by alexbeatle View Post
Circuit breakers protect device, that's why you choose them by the FLA.
Fuses protect the wires, that's why you choose them based on the wire size.
That is not correct

Quote:
Originally Posted by alexbeatle View Post
The topic is closed as I've gotten my answer elsewhere.
Thank you, all.
Makes me wonder what 'diyer' answered your question.

Anyways, thanks for stopping by, and filling out your profile like the Moderator asked
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Old 06-12-2019, 10:21 AM   #11
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Quote:
Originally Posted by CoolWill View Post
That's just silly.



I'll let you know when the topic is closed!
Hi Willy
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Old 06-12-2019, 10:46 AM   #12
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Quote:
Originally Posted by alexbeatle View Post
Circuit breakers protect device, that's why you choose them by the FLA.
Fuses protect the wires, that's why you choose them based on the wire size.

The topic is closed as I've gotten my answer elsewhere.

Thank you, all.
Greatest post ever

So all of my wires are not protected in my house since i have no fuses
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Old 06-12-2019, 10:49 AM   #13
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Quote:
NFPA70 (replacement of the NEC)
Wrong -NFPA70 is the NEC

Quote:
Circuit breakers protect device, that's why you choose them by the FLA.
Fuses protect the wires, that's why you choose them based on the wire size.
Wrong again- Hire an electrician.
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Old 06-12-2019, 01:06 PM   #14
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Greatest post ever

So all of my wires are not protected in my house since i have no fuses
You're correct, I did not explain myself correctly.
Either fuse or CB can be used as a ground-fault or short circuit protective device.
When it comes to motor control circuit, you may put a Fuse\CB as per the device requirements and Fuse\CB as per the wire requirements.
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Old 06-12-2019, 04:09 PM   #15
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I'm still hung up on Connectors or Conductors,...
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Old 06-13-2019, 08:53 AM   #16
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Ground fault protection fuses?
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