Requirements for Surge Protectors at the System Panel

This is a perfect example why inspectors should take a little time to learn how electricity works. Most of the electrical questions I see in home inspector forums wouldn’t need to be asked if the inspector had a basic understanding of electricity and electrical systems. Most HI electrical courses only present the HI, or future HI, with a bunch of random facts to memorize.

The current carrying capacity of a conductor is a function of both time and current. A surge suppressor will carry current for a very short time, typically less than the duration of only a few cycles.

Every component in a residential electrical system is designed to handle a minimum of 10,000 Amperes. The surge suppressor is no exception. If 10kA were to flow through the suppressor or it’s conductors for only a few cycles, there would be no deleterious effect whatsoever on the conductors, the suppressor, or any other electrical component.

Furthermore, the accepted industry ratings for conductors are very conservative. There are many variables that affect a conductor’s current carrying capacity. In most cases, a conductor will carry more than its rated Ampacity for a long time before there is any damage.

In the case of a surge suppressor, if it were to fail in such a way that current continues to flow (the odds of which are extremely low), the 50A breaker would trip long before the conductors are damaged.

Surge suppressors generally act as a shunt to clamp the Voltage. They have a high input impedance. When a device such as an MOV fails, they fail open. Whether, an MOV, Selenium diode, electronic, or any other type, they all have the same essential characteristics. It is because of their design that they almost never fail in a closed (conductive) state.

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What does that mean? How can you have unlimited Amperes? Residential transformers are designed to have an internal impedance that limits the AFC to 10kA. The pigtail would readily conduct more than 10kA. Therefore, the limiting factor cannot be the pigtail.

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George,

Well said, surge suppression is a pretty deep subject, I spent many, many hours on different manufacturers seminars, continuing education, and training just on that one subject and the deeper you get in understanding it the more there remains to be learned. Not only that, once you start to feel caught up, the technology shifts in a new direction and a whole new topic opens up.

As for this particular unit, its not bad for a residential protector, the ratings are similar to what you would want protecting a small/medium sized commercial building and I don’t remember the price being too bad, especially for whole home surge protection versus point of use surge protectors. All surge protection has a lot of limitations though, that’s the nature of it.

Ratings:
https://www.eaton.com/us/en-us/skuPage.CHSPT2ULTRA.specifications.html

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I find both to be true. And it can be said for all the trades we are called upon to evaluate.

I see one thing that is refreshing with most of the posts here. Is it safe? Will it perform or is it preforming? From there, be prepared to go down the rabbit hole.

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It means getting the last word with dumb misinformation … …

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I was just reacting to the thread and OP’s concern over the wires to the surge protector being a problem. The instructions for the external surge protectors say to keep the wires “short”. There’s nothing shorter or thicker than having no wire at all.

I did not mean to imply that unlimited amperes would actually flow, and apologize for the loose wording.

As others have pointed out this is not a case of trying to conduct huge amounts of energy. But that said the closer the surge protector is to the source, the better. All other things equal an internal panel mounted surge protector could be expected to outperform a remote panel mounted surge protector. And an exterior device at the drop would outperform both.

The spike and surge current need not go to or through the transformer… at all. It can be induced directly in the overhead wiring, the service drop, or home wiring, or anything.


For background: I have been part of a team that designed, installed, field and laboratory tested industrial surge protection for high altitude radio equipment that occasionally takes direct lightning strikes. Those systems all used layered approaches: fast small capacity surge devices paired with slower higher capacity devices and then physical spark bypasses for the largest currents. We always took pains to keep the high transient current paths short, because when they’re not short the electricity finds its own way.

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I ran into one of these Eaton Ultras yesterday attached to a 30 amp breaker. I read the manual and it says Recommended 50 amp breaker. This is not something I’d write up as a defect, should I even bother mentioning it? I did in this case, but just in text that the surge protector may not provide full protection.

Thoughts? Worth mentioning if I find it again?

Sorry for the Necro thread, but figured I’d see what folks have to say about it.

If it’s not installed per the manufacturer’s instructions, I would mention it. Florida Code says everything should be installed per the Code and the manufacturer’s installation instructions. YMMV

The issue is the wording in the manual.

“A dedicated 2-pole 15 ampere circuit breaker is
recommended for use with CHSP devices, but use a 2-pole 50
ampere circuit breaker to achieve the full published ratings of the
CHSPT2ULTRA device.”

A 30 amp breaker IS exceeding the minimum recommendation, but not meeting the maximum recommendation. Hence my confusion.

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Just mention it and sight your reference. If something goes astray in the future you’ve CYA.

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Recommendations are not enforceable. They are suggestions.

Eaton recommends the 50 amp OCPD so that it will perform to its specification. Although not a code requirement IMO it should be mentioned.

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I think that you’ve read this incorrectly, it mentions two specific models of SPD either the CHSPT2SURGE or the CHSPT2ULTRA. Only the Ultra has the 50 amp OCPD rating.

But they mention CHSP devices of which both are. They don’t single out the Surge for the 15 amp breaker.

I’m not arguing that bigger isn’t better, but it does say “CHSP DEVICES” plural, not singular.

I will definitely mention it in the future though. Thanks for your insight. It seems that manufacturer could provide better guidance.

One hat I wore was that of a programmer, and specially when dealing with PLCs and ladder logic, it’s either true or it isn’t, not sorta :slight_smile:

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The directions explicitly say that there are two different models of the same device (SURGE and ULTRA) with two different recommended OCPD sizes. If the ULTRA is installed then the recommended OCPD is 50 amps. If the SURGE is installed then the recommended OCPD is 15 amps.

Table 1. Recommended Dedicated Circuit Breaker to Achieve

Published Rating:

Catalog Number Pole Rating
CHSPT2SURGE 2-Pole 15 ampere

CHSPT2ULTRA 2-Pole 50 ampere

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Here’s the relevant text for the peanut gallery :slight_smile:

Clearly you need a 50amp breaker for the ultra to get full protection. Perhaps if you put it on a 15, you get the same protection as the surge? Regardless really, the ultra is not reaching it’s full potential so it’s documentable at least if not on the 50amp breaker. “The manufacturer recommends a 50 ampere circuit breaker to achieve published rating”

breakers

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