Anyone use out door surge suppressor for HVAC unit?

[alarmguy]

Just curious, about to order one unless anyone knows any better brand. New home on the coast and figure spikes are more a reality here. Our last home my neighbor has had his two HVAC units replaced and the company themselves installed two surge suppressors on the outside condenser power supplies which put the thought in my mind.

Anyway, purpose of my post is if anyone uses them or has knowledge of anything better than these two units. Im specifically interested in this style suppressor only. I am very up to date on whole house and individual ones.

They both cost the same $60 ish, both same UL specs

 

[oil pan 4]

Nope just bought a bag of metal oxide varistors probably 10 years ago. 150vac for 120v stuff and 300vac for 240v stuff. and add them in as needed.

 

[Kantaro]

I was going to install one to protect our $$$ heat pump but ended up installing a whole home SPD instead. They work and are cheap insurance. The Intermatic AG3000 is rated for 50 kA while the Mars 83905 is only rated for 20 kA. Both come with 18" of stranded 10 AWG wiring. Interestingly, Mars says to install on the load side while Intermatic says to install on the line side.

There is also the Robertshaw STXH240S05 and DITEK DTK-120/240CM+, both rated for 50 kA.

 

[E150GT]

The best way to do it is in layers. Every panel needs protection. I myself am going to install a Siemens fs140 on the main. Then the sub panel in my house which runs all the interior stuff except any 220v stuff has an Eaton CH surge breaker in it. The garage will get a Siemens surge breaker in its panel and the ac disconnect is going to get replaced with a small panel that will also have another Siemens surge breaker in it. Any electronics should also be plugged into surge protector strips as well.

 

[NormanBuntz]

My electric cooperative in FL has a program I opted for. They offered a whole house surge protector that attaches beneath the electric meter. It was a two minute installation by them. Two options: $5.95 a month added to my bill or a $349 one time charge. I opted for the six bucks. My previous HVAC company, which I fired, wanted $595 installed.

 

[nomas]

I was going to install one to protect our $$$ heat pump but ended up installing a whole home SPD instead. They work and are cheap insurance. The Intermatic AG3000 is rated for 50 kA while the Mars 83905 is only rated for 20 kA. Both come with 18" of stranded 10 AWG wiring. Interestingly, Mars says to install on the load side while Intermatic says to install on the line side.

There is also the Robertshaw STXH240S05 and DITEK DTK-120/240CM+, both rated for 50 kA.

I find that interesting . A 50 ka rating and it's wired with #10 awg .

 

[CDX825]

On the newer units that are inverter driven compressors its a must have. Bosch actually requires them to be installed with their heat pumps. We use the intermatic ones.

 

[alarmguy]

I find that interesting . A 50 ka rating and it's wired with #10 awg .

The wiring of suppressors do not require wiring as we know it

 

[alarmguy]

On the newer units that are inverter driven compressors it’s a must have. Bosch actually requires them to be installed with their heat pumps. We use the intermatic ones.

Also @Kantaro
Yes, the Intermatic looks to be the best,

Good info CDX825 thanks. Interesting you mention inverter compressor like my refrigerator, I do have plug in suppressors on all our appliances

While I am at it I am going to install a Square D suppressor that snaps onto the buss bar in the panel.
Which brings me to ask myself another question. Since the Square D buss surge suppressor is only rated at 25k I was thinking about installing two of them. I saw a reference someplace and forgot where. Not sure if that is overkill, we have underground utilities here. I also read some debate if the surge on a breaker panel really needs to be first slot near the mains. It sure would be nice if I didn’t feel the need to move all the breakers up two slots

And because I overthink things if I put two on the buss maybe I don’t need another on the AC because the unit is literally on the outside wall of where the breaker panel is. I mean there must be about three feet of wire through the wall to the outdoor AC electric box

So I can install all three or just two.
One on the buss and one outside at the AC unit or two on the buss and one outside.
This is the buss surge, previous post is going to be Intermatic for AC unit outside

 

[nomas]

The wiring of suppressors do not require wiring as we know it

Can you educate me on that or point me to somewhere that explains it ?

 

[alarmguy]

Can you educate me on that or point me to somewhere that explains it ?

Maybe someone can help me out here, I only ran across this the other day researching SPD's Im trying to find where I read it, if I do I will post the link, if I am wrong, maybe someone can post a link too *LOL* Im trying.
If I remember correctly it has to do with the short wiring and short duration of a surge or something like that. I wish I didnt post this now without backing that up. If you notice the time on my post it was 3AM *LOL* Dog woke me up to go outside and I couldnt fall back asleep for a while.

 

[alarmguy]

@nomas
Ok, I found another reference to this (even though there are more and this wasnt the original that I saw) and explains why I posted what I did at 3AM I highlighted below why I posted what I did.

"The instructions for the HEPD80 allow for the use of a 30A maximum breaker; this isn't an issue since the conductors to the SPD carry practically no current in normal operation, and the device can't generate an overload condition, so short-circuit/ground-fault protection is the only concern here, and UL has tested the device with 30A breaker protection."

Here is a link to the whole thread;

Is this a correct installation of a whole house Surge Protector?

Is this a correct installation of a whole house Surge Protector? Note that it's not closest to the main lugs, will that matter? I was unable to bring it closer to the main lugs since those had sp...

diy.stackexchange.com

Some more vague references, I think the key here is the instructions with the particular device. But an explanation that how long the lead is more important than wire size... still I wish I had something concrete and I would edit out my remarks if the time hasn't past... yet one just has to follow the directions with the device.

Correct Installation of Hard-Wired Surge Protective Device | NEMA Surge protection Institute

www.nemasurge.org

 

[nomas]

Alarmguy , my experience with " surge protection " comes mostly from my career in the electric utility business . Most of that was in the high voltage substations . Lightning arrestors ranged from the size of your fist to massive arrestors that were taller than me . And I have seen the big ones totally destroyed by a direct hit . That's why I'm skeptical of the ratings of these small surge protectors when you start talking about 50 thousand amps , etc. I would love to see them being tested in a high voltage lab .

 

[Kantaro]

I find that interesting . A 50 ka rating and it's wired with #10 awg .

Not an electrical engineer but my understanding is that the surge is so brief that it does not exceed the capacity of the wiring, as the current capacity of a wire is based on both amps and time. These are all UL listed so I have to assume they did the math

 

[Kantaro]

Also @Kantaro
Yes, the Intermatic looks to be the best,

Good info CDX825 thanks. Interesting you mention inverter compressor like my refrigerator, I do have plug in suppressors on all our appliances

While I am at it I am going to install a Square D suppressor that snaps onto the buss bar in the panel.
Which brings me to ask myself another question. Since the Square D buss surge suppressor is only rated at 25k I was thinking about installing two of them. I saw a reference someplace and forgot where. Not sure if that is overkill, we have underground utilities here. I also read some debate if the surge on a breaker panel really needs to be first slot near the mains. It sure would be nice if I didn’t feel the need to move all the breakers up two slots

And because I overthink things if I put two on the buss maybe I don’t need another on the AC because the unit is literally on the outside wall of where the breaker panel is. I mean there must be about three feet of wire through the wall to the outdoor AC electric box

So I can install all three or just two.
One on the buss and one outside at the AC unit or two on the buss and one outside.
This is the buss surge, previous post is going to be Intermatic for AC unit outside

View attachment 226833

While whole home SPDs are required by code now, I haven't really found any authoritative sources on how to properly size SPDs other than guidance from manufacturers themselves. Siemens sizes their whole home SPDs based on regions, starting at 60 kA:

Canada:

https://images.thdstatic.com/catalog/pdfImages/1c/1c101975-5763-413d-ae24-f18b14d431ee.pdf

Here's a table from Eaton, where 50 kA is the minimum (relevant code section is 230.67 so see blue column for distribution panelboard, subpanel for Type 2 SPDs):

https://www.eaton.com/content/dam/eaton/products/backup-power-ups-surge-it-power-distribution/surge/NEC-code-requirements-surge-devices-SA158003EN.pdf

I'm on the west coast so I just went with a Schneider HEPD80, installed on a double pole 30A breaker closest to the main breaker. The installation instructions didn't specify the breaker location, but their illustrations showed it closest to the main breaker. It made sense to me that the surge would "hit" the SPD first before the other circuits. It's also easier to service the SPD when connected to a breaker, so that you can just shut the respective breaker off instead of the main breaker. What seems more important is ensuring the wiring has low impedance (ie no bends, loops, as short as possible, etc).

IMO, I would prioritize a whole home SPD with adequate protection based on the above, then throw in another SPD at the HVAC disconnect for good vibes.

 

[nomas]

Not an electrical engineer but my understanding is that the surge is so brief that it does not exceed the capacity of the wiring, as the current capacity of a wire is based on both amps and time.

Current capacity of wire, also known as ampacity, is the maximum current that a wire can carry continuously without exceeding its temperature rating .

 

[alarmguy]

@Kantaro
I just ordered this for the breaker panel to keep things simple ( I think I can always add a second one if I want) I grabbed the first amazon photo I could find, multiple sellers on amazon

and this for the HVAC unit

I appreciate your post and will re-read it later again. I wanted to keep things simple and not cut drywall to mount an external breaker surge, even though the externals are much more robust. I do think (it's a topic of discussion though) I can add another to the breaker buss (photo #1) buss and double the effectiveness. Since I have none and never did have any whole house, I have always had every appliance in my home (except AC and Dryer) on plug in types I was never concerned but I do these things for fun and now back on the coast it maybe more prudent. I am a firm believer in them and a firm believer that even though most people think a surge has to be catastrophic and render an electronic as "fried" that is not true, surges even from within the home can and do slowly wear down electronics. IN decades I never had an appliance failure and I think it is by being prudent.
When first married a very long time ago, we did have a nearby lighting strike and heard the loud static electricity enter our apartment, it fried some electronics others were ok. I was also in the security industry and wow, every summer I have seen the damage of fried electronics. One must know, none of these will prevent damage from nearby/direct lightening but somewhere a little further away it will give protection. Thing is, it can be the everyday surges created within ones own home that wears things down.

 

[alarmguy]

Not an electrical engineer but my understanding is that the surge is so brief that it does not exceed the capacity of the wiring, as the current capacity of a wire is based on both amps and time. These are all UL listed so I have to assume they did the math

Correct look at it this way, no home wiring to a surge suppressor can handle as we are discussing here the amps that a surge suppressor handles.
@nomas to put this in perspective at what we are missing here, is we are thinking of household wiring in the context of suppressing over 10,000 amps which is impossible. A surge lasts as little as a few millionths of a second.
It's more about high voltages jumping through electronic circuits ... here is an interesting read.

Whole House Surge Protectors: How Effective Are They?

Don’t count on power strips to safeguard your home and fragile electronics. Read on to learn about the cost-saving alternative of installing a home surge protector.

www.thisoldhouse.com

PS, REALLY ENJOYING THIS THREAD and DISCUSSION !

 

[Kantaro]

Current capacity of wire, also known as ampacity, is the maximum current that a wire can carry continuously without exceeding its temperature rating .

Yes, and surge != continuously

 

[tcp71]

I added one of these to the panel in March. Our furnace control board died and was replaced under warranty. The tech mentioned that it would be a good idea to have one as, in his words, " all those EV chargers in people's houses are causing spikes". I doubt that is the problem, but added one for other possible spikes.

Now thinking maybe another one on the AC unit would be helpful as well.