Mixing MNSPD with other arrestors(cheap ones)

Started by dapdan, July 17, 2023, 07:25:02 AM

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I have a client that a previous installed setup one of those all in on fuse boxes with a din rail surge arrestor already installed and I was wondering if it was safe or even recommended to just parallel in one of midnite arrestor into the circuit or should I just remove completely and install the SPD. Just wondering if parallel would do harm or not.

I recall midnite doing some test on some earlier version of lighting arrestor. Have you guys done any with the latest versions (chinese) made din rail arrestors. They look a little on the flimsy side altho I am not sure that size would matter for surger arrestors tho.

Thanks much.

DamaniScreenshot 2023-07-17 072422.png


Hi Dan !

No we have not tested any real SPDs.  Just those old fake ones.

Adding ours in parallel with the DIN rail SPDs should not hurt anything.

K7IQ 🌛  He/She/Me


Hey bob,

Thanks much. Good to know. I wonder how they really stack up tho. It is hard to believe they do the same job as yours in such a small filmsy looking package. And also the price for all those breakers, fuse devices, surge arrestor, mc4 connectors and box is cheaper than one MNS sPD. SMH.


The MidNite SPD will probably/likely have a different turn-on voltage than your other SPD.

Whichever one has the lower voltage MOV (assuming they use MOVs) will take the strike first.

If they are close in turn-on voltage and the lightning strike is close by, they may both help protect.

Then again, one (likely the other SPD) may take the hit and blow up and then the MidNite SPD might be all that's left in which case you didn't need the other one in the first place.  :) LoL.

Couldn't you just use a regular breaker/disconnect and a MidNite SPD ?   Things may be more expensive over there yonder.


K7IQ 🌛  He/She/Me



It is an existing installation that I am going to modify/improve so I can remove the existing breakers/fuses and replace with midnite gear. They are din rail mounted. It is just to see if the box is deep enough. The box seems ok as plastic/pvc boxes goes.