Any Downside To Installing A Whole Home Surge Protector?

NO

@analogj  I think it's a good idea and you might read a bit on this thread:

From a couple of papers I’ve read, it’s best to connect a surge protector to neutral, not ground. It prevents high voltages from appearing on the chassis of connected devices (basically anything with a ground prong). Plus, the neutral is a lot fatter conductor than ground.

No downside. I do want to point out that even whole house surge makers recommend you supplement with protectors at delicate devices due to a couple of issues:

• Clamping voltage of whole house protectors is usually pretty high, 600 to 800V.  I have a WH protector and the one device I lost during a lightning strike was a laptop plugged in directly overnight.  It was an old laptop, but still, I could have gotten more use out of it.
• The distance between the panel and device may be long enough that an induced surge via electromagnetic coupling to a lightning strike can’t be protected by the panel alone.

Lastly, the 2020 NEC requires whole house surge protectors so you’ll be moving your panel towards the latest standards. Highly recommended.

No downside here - one thing i did notice

• I’m in a new house and the breakers always seemed super sensitive 
  • i.e. some of them tripped whenever we had a power outtage
• Once I installed the surge protector the breakers now seems to work normally
• BONUS !

Regards - Steve

I have whole home surge protectors in my 2 panels due to the severity of lightning that we get in  western Tennessee . I haven’t experienced any SQ downside in either of my 2 systems from WHSP nor the surge suppression built into my systems’ power conditioners

I’m wondering if there is any downside to installing a whole home surge protector at the mains.

@analogj 

No...

What manufacture is the electrician going to install?

If the SPD (Surge Protection Device) will be mounted on the outside of the panel enclosure it is important to install it close to the main breaker . Install the 2 pole breaker for the SPD connection to the panel Hot bus in the two spaces just below the main breaker. Have the electrician relocate breaker(s) to free up the two spaces if needed for the SPD 2 pole breaker. Leads from the SPD to breaker must be kept short as possible. Also keep the SPD neutral lead as short as possible. Same for the SPD ground lead. Usually in a main electrical service panel the neutral bar is also used for the equipment grounding bar. Electrical service entrance neutral conductor is bonded to the metal enclosure as well the neutral is connected to mother earth.

Make sure the electrician inspects the electrical service’s Grounding Electrode System. He will know what that is. Have him inspect all connections. Clean and tighten as needed. Add a ground rod(s) if needed to the existing ground rod(s). The lower the electrode to earth resistance the better. NEC electrical safety code only requires 25 ohms or less. That is way too high for good lightning SPD protection. IEEE recommends 5 ohms or less...

Here is an example of a very good SPD. Siemens also makes good ones.

CHSPT2ULTRA | Eaton CHSPT2 surge protection device

Siemens "First Surge" SPD.

FirstSurge™ - Siemens Download Center

Here is a good video for you to watch. It shows why it is important to keep the SPD as close as possible to the bus of the electrical panel where the electrical power enters the panel and connects to the buss.

Surge Protection - Power Quality - Experience centers showcase

Also worth noting read the manufacturer’s warranty. As a rule the SPD must be purchased from an authorized dealer. Also the SPD must be installed by a licensed electrician.

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@jea48 Thanks for the info. I don't know the brand. I'll check with him. 

He took off the facade of space the breakers are in and determined that there's space inside to install the protector. He also said that he connects to the ground. No mention of connecting to the neutral, as another poster mentions. 

I can try to forward your post to see if it makes sense to him.