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Old 11-11-2017, 05:02 AM   #1
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Branch circuit breaker specification


All products are linked below. I've taken pictures of both my load center and the circuit breaker. I'm going to have this work done by a certified electrician. This post is for learning purposes only.

I have several computers that will be plugging into a PDU. This PDU then plugs into a L6-30R. This L6-30R will connect to a double pole 240V AC 30 amp branch circuit breaker. Following AWG guideline, I will need a 10 gauge wire. I've already gotten the circuit breaker. What is confusing to me is that on the label of the circuit breaker for AWG, it's being labeled as "14-6".

What does "14-6" have to do with 10 gauge wire? What does "14-6" suppose to mean? The 6 in "14-6" suppose to mean 6 connection points. 3 at the receptacle, 2 at the circuit breaker, and 1 at the load panel? What does 14 suppose to specify?

I didn't happen to get the wrong circuit breaker did I? If I am not reading this label correctly, is there a link/website that I can read up on to learn how to read circuit breaker specification?

Thanks.

---

circuit breaker album: https://imgur.com/a/4AyzY

circuit breaker: https://www.homedepot.com/p/Siemens-...?keyword=q230u

PDU: https://www.tripplite.com/5.8kw-sing...taa~PDUMH30HV/

L6-30R: http://www.leviton.com/en/products/2620

Load center album: https://imgur.com/a/FvFHd

AWD guideline: https://en.wikipedia.org/wiki/American_wire_gauge
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Old 11-11-2017, 05:15 AM   #2
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Re: Branch circuit breaker specification


The 14-6 indicates the smallest wire the screw pressure plate can accept and the 6 indicates the largest that will go in the hole. You match your wire to the load and breaker size. 10 gauge is correct.
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Old 11-11-2017, 10:26 AM   #3
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Re: Branch circuit breaker specification


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Originally Posted by chandler48 View Post
The 14-6 indicates the smallest wire the screw pressure plate can accept and the 6 indicates the largest that will go in the hole.
Ahh, so it's a range! Thanks for the clarification.
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Old 11-11-2017, 09:29 PM   #4
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Re: Branch circuit breaker specification


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You match your wire to the load and breaker size.
I have another question if you don't mind. If 10 gauge wire is the correct size for this amp, what's the point of having a breaker support wire from 14 gauge all the way up to 6 gauge?

What are the advantages and disadvantages of going to a 14 gauge wire on a 30 amp breaker? Would going to a thinner 14 gauge wire be dangerous, since the thinner wire can only support up to 25 amp?

What are the advantages and disadvantages of going to a 6 gauge wire on a 30 amp breaker? Future proofing? In the case that you might need higher amp in the future, there's no need to re-do the wiring? Beside the fact that it is more difficult to work on thicker wire, there are no disadvantages?
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Old 11-11-2017, 10:03 PM   #5
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Re: Branch circuit breaker specification


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Originally Posted by 012abc View Post
I have another question if you don't mind. If 10 gauge wire is the correct size for this amp, what's the point of having a breaker support wire from 14 gauge all the way up to 6 gauge?

What are the advantages and disadvantages of going to a 14 gauge wire on a 30 amp breaker? Would going to a thinner 14 gauge wire be dangerous, since the thinner wire can only support up to 25 amp?

What are the advantages and disadvantages of going to a 6 gauge wire on a 30 amp breaker? Future proofing? In the case that you might need higher amp in the future, there's no need to re-do the wiring? Beside the fact that it is more difficult to work on thicker wire, there are no disadvantages?
In some cases it is code compliant to install #14 or #12 on a 30 amp breaker.

Using #8 or #6 would be compliant for a voltage drop issue or requirement.
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Old 11-12-2017, 05:04 AM   #6
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Re: Branch circuit breaker specification


Remember, too this is mass production. I would venture to guess all breakers from one manufacturer come with the same basic casing and connection points. Only the guts are changed to match the needed amperage. Saves money and time to make the breakers to where they will accept a range of wire sizes.
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Old 11-12-2017, 07:35 AM   #7
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Re: Branch circuit breaker specification


A 30 amp breaker is not limited to #10 wire. There are circumstances where different size wires need to be used. One example would be for extra long runs where you need to upsize the wire to avoid voltage drop.
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Old 11-12-2017, 08:16 AM   #8
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Re: Branch circuit breaker specification


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One example would be for extra long runs where you need to upsize the wire to avoid voltage drop.
Ahh I see. So about how long in feet does the wire need to be before it needs to be up size?

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Old 11-12-2017, 08:19 AM   #9
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Re: Branch circuit breaker specification


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In some cases it is code compliant to install #14 or #12 on a 30 amp breaker.
Would you mind giving a real world example of when it would be necessary to use a smaller wire (#14, or #12) on a 30 amp breaker?
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Old 11-12-2017, 10:51 AM   #10
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Re: Branch circuit breaker specification


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Would you mind giving a real world example of when it would be necessary to use a smaller wire (#14, or #12) on a 30 amp breaker?
Motor circuits. Breaker is upsized for inrush on startup.
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Old 11-13-2017, 04:13 AM   #11
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Re: Branch circuit breaker specification


Quote:
Originally Posted by 012abc View Post
I have another question if you don't mind. If 10 gauge wire is the correct size for this amp, what's the point of having a breaker support wire from 14 gauge all the way up to 6 gauge?

What are the advantages and disadvantages of going to a 14 gauge wire on a 30 amp breaker? Would going to a thinner 14 gauge wire be dangerous, since the thinner wire can only support up to 25 amp?

What are the advantages and disadvantages of going to a 6 gauge wire on a 30 amp breaker? Future proofing? In the case that you might need higher amp in the future, there's no need to re-do the wiring? Beside the fact that it is more difficult to work on thicker wire, there are no disadvantages?
there was a discussion on another thread (I've forgotten which) about installing sub-panels, and whether to install the same size breaker at each end, and Codes and inspector preferences and so on ... I have a Service Panel which feeds sub-panels in other bldgs, and have smaller breakers in the sub-panels than in the service panel, specifically so that the sub-panel will trip first. The breaker in the service panel protects the wire, which for cost considerations I bought in bulk and all the under-ground in-conduit wires are the same size, but most of my sub-panels have smaller breakers. My inspector was fine with that.
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Old 11-13-2017, 11:21 AM   #12
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Re: Branch circuit breaker specification


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and have smaller breakers in the sub-panels than in the service panel, specifically so that the sub-panel will trip first.
So, how many times has one of those sub-panel's breakers actually tripped first and saved a walk ?
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Last edited by Oso954; 11-13-2017 at 11:26 AM.
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Old 11-13-2017, 11:39 AM   #13
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Re: Branch circuit breaker specification


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there was a discussion on another thread (I've forgotten which) about installing sub-panels, and whether to install the same size breaker at each end, and Codes and inspector preferences and so on ... I have a Service Panel which feeds sub-panels in other bldgs, and have smaller breakers in the sub-panels than in the service panel, specifically so that the sub-panel will trip first. The breaker in the service panel protects the wire, which for cost considerations I bought in bulk and all the under-ground in-conduit wires are the same size, but most of my sub-panels have smaller breakers. My inspector was fine with that.

The breaker in a sub panel is a disconnect and can be any size, smaller, larger or the same as the feeder breaker in the main. The sub having smaller breaker than the main is no guarantee it will trip before the main. A dead short will cause hundreds of amps to flow, which trips first depends on which one reacts the fastest.
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Old 11-14-2017, 04:35 AM   #14
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Re: Branch circuit breaker specification


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So, how many times has one of those sub-panel's breakers actually tripped first and saved a walk ?
Depends who is working tools ... not EXPECTING the dead short problem unless something goes wrong, but the smaller breaker is because SOME people get involved in their work and plug in too many tools at once.
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