1

Putting in a MrCool 12k btu mini-split and wish to add a Square D sdsa1175 to the outside disconnect box. The SPD has 3 wires (2 black, 1 white), which (I assume) is normally for a 230v system where both the black and white wires from the breaker would be hot, and the SPD instructions show the 2 black wires going to the line connections and the white going to ground. Can I use this device in my disconnect box where the white wire from the breaker is a neutral? I'm thinking that the white would go to neutral, one black would go to hot (both on the line side) and the other black wire would just be capped off. Is this correct and safe? Where I live, I cannot get a SPD except for this Square D model, and if I order one online, I miss my opportunity to install it for several weeks due to my availability.

Jimmi Salvatore
  • 11
  • 2
  • 1
    I'm not the one to answer your question, but to address your last sentence: Waiting a week or 3 to install the proper surge protector is better than rebuilding the house because the incorrect one caused it to burn down. I know you may be hot & uncomfortable, but doing the right thing is worth the wait. If someone tells you this is the wrong one, please skip the "get-it-done-itis" urge to go ahead with the wrong thing... – FreeMan Jun 04 '22 at 11:40
  • 1
    I have no intention of using an improper SPD. Square D makes the same device with 2 wires instead of 3, and if I learn that the 3 wire (with one black unused) isn't recommended, I won't use it. The truth is, I went to FOUR supply houses in my middle-of-nowhere area, and no one could answer my question conclusively. I have a friend who has done quite a bit of electrical work tell me how to use this one - just wanted to get some feedback. – Jimmi Salvatore Jun 04 '22 at 11:58
  • If they make a different device, it is possible that using the wrong one will leave you with just a paper weight. Square D should be able to tell you if yours will work or not. – crip659 Jun 04 '22 at 13:01
  • I understand this. Truth be told, Square D tech support isn't what it used to be. I spoke with someone there yesterday, and it was someone who had zero electrical experience and was reading from stock info that they had available, hence the reason I am here trying to get someone that may have some tech knowledge on the subject. As far as having the 'wrong' device, I'm not sure that would be true. It would be like having a 3-way switch on hand, and wanting to use it as a simple 2-way. It's certainly doable and safe, just have to wire it correctly. That's what I am trying to learn here. – Jimmi Salvatore Jun 04 '22 at 13:33
  • You could install it at the other end of the cable, at the breaker box, where both hots are available....IIRC, you've got half a 2 pole breaker sitting idle now, so easy to do on this circuit. – Ecnerwal Jun 04 '22 at 17:28
  • I would be putting the SPD at the main panel this way you get both legs protection for the home not just 1 leg. – Ed Beal Jun 04 '22 at 17:54
  • With all due respect to everyone's level of knowledge, when it comes to a breaker box, I'm not comfortable doing more than swapping out a circuit breaker. I just thought it would be a wise idea to put the SPD on the outdoor disconnect box where the mini-split is located. While a whole house SPD is a great idea, I'd rather let my son have an electrician do that at a later time. We are replacing an old minisplit that had, I suspect, a fried circuit board, and I think that a SPD right there would be an immediate benefit. – Jimmi Salvatore Jun 04 '22 at 18:05
  • When your son can do that, you could just up-cycle this suppressor to be the whole house unit. It's made for that. Manual here. – Harper - Reinstate Monica Jun 04 '22 at 20:16
  • Question... to place it in the breaker box, do I put a dedicated breaker in for the SPD only? Obviously, if there is an open slot I would do that, but what amp breaker do I use? Also, since there are 2 black wires, am I putting those on the two lugs of let's say, a double breaker? I will obviously do it this way if it just means adding a breaker. – Jimmi Salvatore Jun 04 '22 at 20:48

1 Answers1

1

It should provide protection, but the indicator light won't come on

According to the Square-D FAQ entry on the topic, the indicator light on the SDSA1175 will not function if only one hot wire is connected. However, it should still provide line-to-ground protection for the connected hot wire in that circumstance.

ThreePhaseEel
  • 83,293
  • 29
  • 137
  • 230