I am interested in installing a whole house residential surge protector. I don't have enough room in my main panel inside my house. I am thinking of buying one of these uints and installing somewhere near the main 125 amp breaker next to the electrical meter, since it is about 30 feet from the main panel inside and I hear it is best to install closest from the mains.

What items would I need to install (Example: weatherproof breaker box, additional breakers, wire guage, etc..)?

How would I wire to the mains?

Whole House Surge Protector

Whole House Surge Protector

Main breaker (Outside next to electrical meter) Main breaker (Outside next to electrical meter)

Service Panel Service Panel

  • It's best to install it closest to the loads you're trying to protect. Have you not changed the configuration of this panel? Jun 1, 2018 at 13:44
  • Due to the space constraints of the interior service panel, I have yet to change it.
    – Rick
    Jun 1, 2018 at 13:51
  • I thought in our earlier review, you identified some A/C breakers that are completely unused. Pull those wires off, cap them, and connect the surge protector's wires there. Bada-bing. It's better for it to be a 2-pole breaker, but two 1-poles will do. Just they need to be on opposite poles. Jun 1, 2018 at 14:58
  • Whole house systems are best at the main this is were the damaging spikes come from the utility line. In any case your main breaker could be turned off and a larger panel installed it looks like your local panel is already full of doubles.
    – Ed Beal
    Jun 1, 2018 at 15:02
  • Sure, if we're going with the logic "All damaging spikes come from the utility line because it certainly wouldn't come from any of MY awesome equipment!" Or as Pogo said, "My toaster keeps tripping a GFCI. What's wrong with the GFCI?" OP has posted previously with an extensive discussion of this particular panel. Jun 1, 2018 at 15:05

2 Answers 2


You'll have to install it in what you put in for a replacement subpanel, unless you want to do concrete work

Here's the rub -- that meter-main of yours is basically a boat anchor. You can't realistically replace it (conduits set into concrete act as a practical bar to that even if you got all your other ducks in the row with the utility pulling power, getting the permit needed, and finding a replacement that'd fit the space available), and you can't expand from it either as it only has room for that one main breaker, never mind having to screw around with the concrete just to get at a usable knockout.

The good news is that installing the surge protector into the subpanel will still work well enough -- it just needs to be near the breaker feeding it, and that breaker should be as close to the primary (would say "main" but that's not right in a setup like yours) set of bussing as possible.

If you're up for chiseling out concrete (carefully!)

In order to install the SPD at the meter-main, you'll have to:

  • Chisel away enough concrete to access a 1/2" KO on the lower right of the box and a notch extending about 6" out to the right from that KO, then make the KO in the lower right of the box using a KO punch set since your box doesn't have a twistout there.
  • Fit a 1/2" prefab RMC elbow to the knockout with a locknut so that the free end points out (beats field bending, huh?).
  • Install a NEMA 3R "spa panel" enclosure (BR24L70RP if you're staying in BR) to the concrete behind it so that the prefab elbow goes in the twistout on the back of the enclosure, and fit a ground bar (GBK5 for BR) into the space provided in the enclosure. Make sure the bonding screw or strap has been removed from this panel.
  • Disconnect the existing wires from the breaker lugs and neutral lug and land them on individual 3-way insulated setscrew connectors ("Polaris connectors"), torquing the connector lugs to spec.
  • Use short lengths of aluminum wire matching the existing feeder wire to pigtail the connectors to the existing lugs, torquing all connections to spec.
  • Take 8AWG THWN (black/black/white) and pull it through the short elbow, attaching them at one end to the corresponding mechanical splices and at the other end to the appropriate lugs in the new mini-subpanel, torquing the connections to spec. Why 8AWG? It can handle 50A at 75°C, 3 8AWG wires will fit down a 1/2" conduit, and we're legal to use this because we are following the 240.21(B)(1) case of the NEC feeder tap rules. Note that the feeder tap rules require the wire to be in conduit -- a cable wiring method simply won't fly here.
  • Install a 50A 2-pole breaker (BR250 for BR) into the spa panel enclosure.
  • Fit the CHSPT2ULTRA into the knockout on the bottom of the spa panel. Land the hot wires on the breaker lugs, the neutral wire on the existing neutral bar, and the ground wire on the ground bar you fitted (it's fine that it's the only wire there).

(And this is why I recommend installing the surge protector into the new subpanel -- it's far easier that way.)

  • I had chatted with Eaton and they recommended that I could install a 50 amp breaker box next to the main meter main and connect the SPD there. Not entirely sure how to wire from the main breaker to the 50 amp breaker, though.
    – Rick
    Jun 5, 2018 at 10:04
  • Yeah, the problem is getting wires out of that meter-main of yours @Rick -- normally I'd be down with what Eaton support is recommending, but even with a feeder tap to the 50A breaker, there's still the issue of wiring the dang thing with all that cement in the way... Jun 5, 2018 at 11:22
  • I can cut a notch on the box for the cables to pass just enough to the side where I can put a weather proof breaker box. I've seen a bunch of people around do that. Still at a loss how wire it up correctly.
    – Rick
    Jun 5, 2018 at 16:26
  • @Rick -- I added instructions for how to do it properly -- you can't do a "notch on the side", you need to do a proper KO in the box, and you'll need to route it in conduit as it's a feeder tap, which makes for more concrete work. Jun 6, 2018 at 1:59
  • I would need to remove the main breaker box to make a knock out hole. Correct?
    – Rick
    Jun 6, 2018 at 13:40

Because almost all of your electrical equipment has microprocessors in them or some form of electronics I have recommended a whole house surge arrestor for a number of years now. Just think of the damage a spike (lighting strike) can do to any appliance plugged into your system. Sure you have insurance but think of that pesky deductible and then there is the argument for actual cash value (depreciation) and then the hassle of getting everything replaced. In other words it's worth it.

Now on to your question. The NEC provides an entire section on these devices now Article 285 (by the way yours is an SPD Type 2. Also it is not raintite so if mounted outside it needs to be in a raintite enclosure N-3R. Article 285.12 tells us we must keep the conductor length as short as possible and avoid any unnecessary bends. Article 285 will also refer you back to Article 230.82 (8) and 230.90 which will tell you that the conductors to this surge protector must be protected with overcurrent protection either in the form of a breaker or inline fuses is you elect to install this at the main breaker or any breaker larger than the required protection.

FYI You can only "double lug" conductors if the lug is rated to receive more than one conductor. Bye the way your doesn't allow it. I also took the liberty to look up the proper breaker size for your SPD.CHSPT2 family of products require a dedicated 2-pole 50 Amp thermal magnetic breaker.

FYI-2 Your panel has major problems. First there are what looks to be 2 #12 or #10 wires tied onto your main lugs in the panel these are undersized and unfused and dangerous, also see double lugged FYI. Second your Panel space is used up. You might go with @Harpers suggestion or consider installing a subpanel right next to it to get some more breaker space.

Finally I would like to say that even if you install the SPD in the panel it is installed to the bus and the only thing it is not protection is the service feeder from the main breaker. So it would be a safe bet it would protect all of the circuits downstream.

Hope this helps and good luck

  • The two cables from the main lines go to two inverter ACs on the roof. They have their own beakers up there.
    – Rick
    Jun 5, 2018 at 10:00
  • Still not protecting the conductors per NEC and still does not rectify the double lug situation. Jun 5, 2018 at 12:52
  • I'd like to rectify problem by that by putting those cables on their own breaker in the main panel, but don't really have much space at the moment. That's another post on itself.
    – Rick
    Jun 6, 2018 at 13:08
  • Was thinking of doing something like this old video on the main outside breaker, but since it requires a 50 amp breaker box, I would connect it to that.
    – Rick
    Jun 6, 2018 at 13:16

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