Surge Protector

Hello,

Is there a way I can add a panel mount exterior rated whole house Surge protector to an exterior mounted main breaker box?

It houses only the one breaker, not designed to accept more, and basically just connected to power coming in from street, and power going out to house.

FYI the panel with all the branch breakers is 30 ft away inside the house. (BTW, Does that technically make it a sub panel?

Thanks!

 

Picture is attached of what we have presently.

 

A panel-mounted surge protector is typically connected to its own breaker. Since you can't add any breakers to the outdoor panel you will need to connect it to the indoor panel.

Yes, the indoor panel would be considered a sub panel as it is not the panel with the first overcurrent device. Since the main panel does not have any branch circuits installing the surge protector in the sub panel would be just fine. The surge protector protects equipment from surges, it does not protect the home wiring.

 

Thanks. There is a new surge breaker in the indoor panel. It replaced the old one which was fried by a surge.

When I took out the old one there was a black fried mark on the bus strip (if that's what you call it) that the breaker pivots into. Seems the house survived a big surge that that killed the device.

The client of this property wants assurance with overkill methods. So if possible, an outside surge device at the breaker cut-off box.

My question is could that be done by replacing that box with an exterior rated box with room to accept the additional surge breaker?

Otherwise can we put a knockout mounted surge device in the existing exterior box?

 

Yes. An outdoor panel with breaker spaces would be the easiest fix.

The issue with connecting a surge protector in the outside box is it does not have anyplace to connect the wires of the surge protector. You may only have one wire connect to one screw. Doubling up wires on a lug is a sure-fire way to create a bad connection and a possible fire.

That sounds normal. Surge protectors are sacrificial items.

 

Effort might be better spent on better grounding methods. Rods, metallic pipes, etc. also, what is surge rating at the existing TVSS? 20, 60, 80 kA?

 

Some surge protectors are classified as 'Type 1' and can be installed without any overcurrent protection. So in theory, it can be connected to the main breaker in your main panel.

But as Tolyn pointed out, you can't just shove the wires into the same lugs. You'd need to correctly 'split' the wires or lugs using Polaris connectors or possibly a lug adapter.

If it were my house, I'd rather spend the money on point-of-use surge protection. A panel protector is good for larger surges, but a quality surge protector or UPS on the computer, TV, stereo equipment, etc is probably money better spent than a second panel mount protector.

 

OK...so to answer various inputs....this house has a main panel breaker SPD, and a sub panel breaker SPD.

It also has the required 2 ground rods spaced accordingly, plus the cold water pipe ground. All of these I put in under the tutelage and permit of a master electrician. (Now if I'm hearing that more ground rods will be significantly better, tell me why, how many and I will do it.)

Even with this all in place...About a year ago when POCO was restored after outage, almost EVERYTHING with a circuit bd in the house blew out. At that point we put in point of use KO SPD's on equipment and wall receptacle SPD's in many places.

Last outage a week ago saw the boiler wifi t-stat blown. So the single woman HO is freaked out and doesn't mind over kill approaches.

Leaves me with a few questions....more ground rods? Will they help? How many?

What about a SPD, I hear about, that installs between the meter and the meter socket? Ramifications? Do these blow? If so then what? No power till an electric guy comes out?

Just as an aside she does have a standby Generac for essential circuits. That's where the sub panel and it's SPD breaker is. Thanks very much!

 

No. You already have one more than you need. Ground rods only voltage/current to ground. A surge on the ungrounded conductors are not helped by a ground rod.

That would need to be installed by the PoCo. That is all their equipment and if it fails would need to be serviced by them.

 

Are these lightning caused appliance failures? Reading reply sounds like POCO caused the issues.

 

Surges from power company switching is obviously a big problem there so I think I'd invest in some surge protection that is better than the plug-in surge breaker type of protection. Eaton makes some very good ones.

Here is an Eaton protector that has much better ratings than the surge breaker type, it wires into a 2-pole breaker in your panel.

https://www.amazon.com/CHSPT2ULTRA-U...05554811&psc=1


Here's another very good one that comes with a $10,000 connected equipment warranty on appliances and electronics.

https://www.amazon.com/Intermatic-IG...2738104&sr=8-5

 

All surge protectors can go bad so they must have a circuit breaker rated for the conductor connecting them to the system.

If surge protector is remote and not connected directly on the main bus it is less effective.

Ohms Law comes into play.

 

IMO, there's not much more 'reasonable' protection you can do. I agree with CausalJoe that not all surge protection is the same, and there are devices with higher protection and higher quality (and higher price). You can start reading the specs involving clamping voltage and response times.

But in the end, surge protection is never 100%. Larger surges will always get through and over-voltage events can fry devices and surge protection can't help.

Lastly, don't forget that other incoming services should be surge protected and well bonded/grounded. Cable TV, telephone, etc can be back-door surge events that can cause significant damage too.

 

Thanks for all the replies. I appreciate that. So here's what I look at now: The house panel is really a sub panel. (Because first there's a 200 amp outdoor cut-off panel that's 30 ft away)

Looking at the surge breaker instructions reads, "This device is suitable for use only in panel boards with grounded neutrals."

AND ALSO...

paraphrasing slightly.... "Optimum protection when used in service entrance panel boards....when used in remote panel boards (aKa sub-panel?) protection is degraded because of added impedance from added length of ground conductor back to this service."

Questions...
What do they mean grounded neutral? The bond strip between the 2?

Are they saying put a SPD in the outside cut off is better?

Why do they always specify attach white wire to neutral bar if surge drains to ground?

No bond exists, as should, on my main sub between Neutral and gnd, so what's the sense of putting a SPD there? Is this just validation for the above points they make?

Thanks again!

 

Home TVSS work with two very different modes. First mode, and the easiest to understand is "differential mode". This is simply the voltage between the L and N conductors. The surge protector puts a voltage sensitive resistor across the line, so when the voltage exceeds a certain value, the device becomes less resistive, starts conducting, and a portion of the surge current turns to heat. This is the type of surge caused by the POCO primary line taking a lightning hit at that conductor. It is shunted a bit by any primary arrestors to earth, but some of the surge remains for you to deal with as it proceeds from the primary to secondary transformer windings. It requires no ground connection to the TVSS for effectiveness on this mode.

The second mode is "common mode", where both L and N are subject to the same disturbance, but it rises above earth. Imagine now the L, and N together are subjected to the same pulse voltage due to a hit on the secondary of the transformer. For this protection, you need conduction to local ground. This is done with a different set of conducting resistors, now connected to earth.

Not to make this too simple, but both DM and CM usually co-exist with a lightning event. The TVSS manufacturer does do a separate test for each mode on the bench to understand the effectiveness of each set of protection devices.

As to the earth/ground reference of the TVSS, it gets interesting. At the main panel, N and G are tied together. So, there can't be much V between N and G at that panel. Not so for a subpanel. The G to N bond can be a long ways away. And you may or may not have a ground rod there. So, significant injected ground currents at that point will cause significant rise above local earth. That reveals the point about getting to earth with large, short conductors. Something the main panel can do much better than a subpanel.

BUT perfectly fine DM protection can still exist at a subpanel or on outlet strips, etc. Just more limited CM protection. Yes, use TVSS at multiple points, but make the one at the main panel larger.

 

Thank you TC guy! I appreciate your input.