# Tandem断路器需要抛出到断路器。有线不正确？ -- electrical 领域 和 wiring 领域 和 circuit-breaker 领域 和 electrical-panel 领域 diy 相关 的问题

## Tandem breaker needs both thrown to break circuit. Incorrectly wired?

10

### 问题

I have a tandem circuit breaker in my main breaker box with two 20 amp breakers. To turn off power my wife's office, I need to throw both breakers. I can throw either one and as long as the other is on, the circuit is still live.

My guess is the electrician who installed this tandem breaker wired it in parallel. In other words, current is flowing through both breakers when closed and both have to be open for it to break the circuit. Does that sound right?

If so, my understanding is that it would take 40 amps of current to flow before this breaker would trip. (20 amps X 2 = 40 amps because it's in parallel)

They used 12 AWG wire on the circuit. That means the wire would basically catch fire before the circuit would actually break. This seems incredibly dangerous.

Are my assumptions correct in this case? I'd like to know so I can get a electrician out to inspect the wiring, since I've spotted a few other oddities in this house.

## 回答列表

18

• 仔细工作！当您无法确保电源关闭时，这是一个危险的情况。假设你遇到的每个盒子就活着。您需要一个较少的接触电压传感器。
• 打开断路器盒并验证有两个12/2电缆进入，每个12/2电缆，每个黑线直接连接到串联断路器上的一个凸耳。
• 开始绘制图表，包括涉及的每个开关和插座。
• 关闭两个断路器。
• 打开受影响的盒子，并断开设备的黑线。盖上电线。我会从你认为最接近破碎机盒的盒子开始，首先在电路上。
• 一次打开​​一个断路器，一次一个，并注意哪条线/设备仍然有电力。这将有助于您弄清楚上游/下游的线头。用数字或描述标记电线（如果可以写足够小）例如"来自霍尔开关"
• 重复，直到你让情况映射出来。
• 报告回到这里，告诉奇怪的人你找到了什么。

Intentionally wiring the two breakers together in the breaker box would be a really stupid (borderline malicious) thing to do.

My guess is that there are supposed to be two independent circuits, but someone has somehow unintentionally joined them together in a junction box or outlet box somewhere along the circuit.

This could be pretty complex. I would recommend having an electrician come check out the situation.

If I were solving this, here is what I would do:

• Work carefully! It's a dangerous situation when you can't be sure the power is off. Assume every box you encounter is live. You'll want a contact-less voltage sensor.
• Open the breaker box and verify that there are two 12/2 cables entering, the black wire of each connected directly to one lug on the tandem breaker.
• Start drawing a diagram, including every switch and outlet involved.
• Turn off both breakers.
• Open a box that's affected, and disconnect the black wires from the device. Cap off the wires. I would start with the box that you think would be closest to the breaker box and first on the circuit.
• Turn a breaker on, one at a time, and note which wires/devices still have power. This will help you figure out which wire heads upstream / downstream. Label the wires with numbers or descriptions (if you can write small enough) e.g. "From hall switch"
• Repeat until you have the situation mapped out.
• Report back here to tell the curious people what you found.

0

The British have an idiomatic design called a ring circuit, where the circuit starts at the panel as normal, visits several outlets, then loops back to the panel. It lands on a breaker rated for 2x the safe wire capacity - which assumes no wire failures. Mind you, the UK also requires switches on every receptacle and fuses on every plug, which helps make this safer for them. Doesn't work in North American standards (or anywhere else in the world).

It looks like here, the homeowner non-electrician was too clever for himself. He decided to fashion a British ring circuit, except fuse each end of the wire for 1x wire capacity. True, that helps with a big defect in UK ring circuits, and a duplex breaker is a savvy choice. It's still wrong for many reasons: least of all, the breakers need a handle-tie for the same reason MWBCs do, and there's no such thing as a handle-tie between breakers on the same pole. You'd have to use a 3-phase breaker and disuse the middle space, which means 3 spaces instead of 1, not that you should even be trying to fix this.

Rewiring to be correct is rather straightforward: Sever the circuit at some opportune location, so instead of a ring circuit, it is 2 circuits. And you're done.

Simply find the right receptacle, remove the downline wires, cap them, tape them so the caps don't fall off (as they are prone to do with a wire-nut on 1 wire), and push them into the back of the box.

The art of it will be in choosing the opportune location. This is where you map the circuit to see where the outlets are, and also where the loads are. You want to split it so it places half the load on each side, or so the expected loads won't overload either circuit. For instance "between a gaming PC and a laser printer" is a great place to split it.

## 相关问题

0  Cloakroom中的消费者单位（电气板）允许吗？  ( Consumer unit electrical panel in cloakroom allowed )

0  Subpanel安装断路器大小：它足够大吗？  ( Subpanel installation breaker size is it big enough )

0  GE断路器不适合电气面板  ( Ge circuit breakers not fitting in a ge electrical panel )

1  蠕动，蠕动，擦拭炉压力开关上的电线使其工作 - 我应该更换开关吗？  ( Wiggle wiggle wiggle wires on furnace pressure switch makes it work should )

1  什么尺寸的电线为150个主要电气服务  ( What size wire for 150 a main electrical service )

0  是一个60A的子面板适用于我的车间/车库吗？ [关闭]  ( Is a 60a sub panel adequate for my workshop garage )

3  主面板和子板的接地要求  ( Grounding requirements for main panel and subpanel )

1  200AMP服务升级失败检查NJ  ( 200 amp service upgrade failed inspection nj )

0  20岁的绅士交换机完全死了  ( 20 year old gentran switch totally dead )

0  两个断路器面板，一个转移开关？  ( Two breaker panels one transfer switch )

1  我的小组是否具有单独的断开连接需要孤立的中性公交车？  ( Does my panel with a separate disconnect need an isolated neutral bus )

0  3“压力缓解  ( 3 stress relief )

1  中国断路器盒（240V分裂阶段？）缺乏中性线和接地总线  ( Chinese breaker box 240v split phase lacks neutral wires and grounding bus )

2  子板上的地面栏是否需要将绑定到子板？  ( Does the ground bar on a subpanel need to be bonded to the subpanel )

1  在电器子板上没有地面酒吧  ( No ground bar in electrical subpanel )

0  我可以将一个3相连接电源转换为两个3相连接吗？  ( Can i convert one 3 phase connection power supply to become two 3 phase connecti )

2  我的现有电气供给我的独立车库是否安全？  ( Is my existing electrical feed to my detached garage safe )

6  如何在房间角落的服务面板附近框架并保持间隙？  ( How can i frame around a service panel in the corner of the room and maintain cl )

4  分开巴士电动机面板问题  ( Split bus electric panel question )

15  断路器中的“手柄领带”和“共同行程”之间有什么区别？  ( What is the difference between a handle tie and common trip in circuit break )

0  电气主板冲洗安装在混凝土墙上  ( Electrical main panel flush mounted in concrete wall )

2  半冲洗安装表面安装（NEMA 3R）面板  ( Semi flush mounting a surface mount nema 3r panel )

-1  电气主板  ( Electrical main panel )

0  将子面板置于家庭办公室/卧室？  ( Putting a sub panel for a home office bedroom )

0  清洁保险丝触点并缩短主电路后没有动力  ( No power to garage after cleaning fuse contacts and shorting a main circuit )