240V 2極熱水浴缸斷開中的零線怎麼辦?


3

我正在計劃安裝熱水浴缸(尚無任何產品)。當前的計劃是:

  • 室內50A 240V 2極GFCI斷路器(添加到現有的100A子麵板中)
  • 從子麵板到外部斷開連接的4線(2線,零線,接地)
  • 從外部斷開連接到熱水浴的4線製

我更喜歡在室內放置GFCI,以使其不受天氣影響。這樣,如果需要更換,裸露的斷開連接相對便宜。

我可能實際上並不需要4線(TBD),但是僅僅擁有4線和麵向未來的產品似乎很愚蠢。

我能找到的大多數(即使不是全部)隔離開關(對於" spa"或空調)都是2極。所以問題是:斷開處的中性線怎麼辦

  • 是否還需要進行開關操作,即是否需要3極斷開?
  • 即使不要求,換成中立點有什麼好處嗎?
  • 如果沒有,如何在斷開連接的機箱內連接兩條中性線?電線螺母?母線?(也許如果使用THWN,它可能只是連續的。)

位置:美國


我應該補充一點,我已經查看了一些斷開連接的PDF(即使它們可用),但沒有看到解決的細節。也許印刷的說明會涵蓋它,但我不想在製定完整計劃之前先購買任何東西。

5

You never switch the neutral, well, "never" is a strong word, sometimes some special generator installations switch the neutral, but almost never should you switch the neutral, just the 2 hots. I like your idea of putting the GFCI inside to protect it.

To connect the neutral, there is usually a small bussbar you can land those on. If your new hot tub doesn't require a neutral, just cap it off in the disconnect.

Your idea about just passing the neutral thru the disconnect unbroken works too.

You got this!


2

Keeping the GFCI indoors will cut the cost of a GFCI disconnect but be prepared to shell out some bucks for indoor GFCI. It's a great idea to still run the neutral, you never know when you might want to change out that cheap disconnect with a little subpanel (think about it). You would just cap the neutral in your disconnect box with a wire nut and leave it disconnected in the main panel. There is no need to switch it and no advantage.

You ask about connecting two neutrals in the disconnect box. I'm assuming you mean grounds since you've already stated you don't need the neutral. The grounds should be connected to a grounding bar in the disconnect which would also ground the box.

If you meant connecting neutrals in the bos in the event you ran them, wire nuts would be the way. Plain disconnect switches usually don't have a neutral lug. If you used a GFCI disconnect then that would probably have a neutral bar that you would attach to.


0

Neutral should not be switched. Ideally the disconnect box supports a neutral bar, but if not a suitable wire nut or any other code compliant wire connection method for in-box connections is suitable. 50A is not a small amount, though, so I'd shy away from wire nuts, as you should be using a 6 awg wire. Putting two of those into a wire nut requires a special wire nut. At this size you should instead consider a split bolt connector.

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Another option would be polaris connectors, which don't require the effort needed to properly insulate a split bolt.

Wire nuts, split bolts, and polaris connectors are less convenient than a neutral bar. You don't have to worry about whether you've tightened and secured the wire nut enough, insulate the split bolt, or take up as much space as all three options. For split bolts, make sure you understand how to insulate it properly - it often requires several layers of two or more different coverings to do properly.

Also please be aware that ground and neutral should be separate at this point. If you place a neutral bar in there you might be tempted to make it look like the main breaker box, and connect both neutral and ground to the bar. This will interfere with the GFCI operation. If you use a a neutral bar make sure it is insulated from the box and ground. Some neutral bars are not insulated, so even if the ground isn't connected directly to the neutral bar, they might be connected due to the way the neutral bar is attached to the metal (grounded) disconnect box.


0

Cap it off at the disconnect

Hot tubs, by and large, are single-voltage, 208/240V loads, connecting to two hots and a ground. As a result, you'll want to simply cap off (insulate) the neutral at the local disconnect using a wirenut of the correct size. There's no sense in bringing it further, nor do you need to provision a pole for switching it, so a bog-standard two-pole air-conditioner pullout disconnect works.