# Surge Protection Question



## sga2 (Nov 14, 2009)

I installed a whole-house surge suppressor system on main panel, CATV and telco lines (Eaton CHSPULTRA, DCXCAB2, and DHW4PT, respectively) last year. Between that and my point-of-use surge protection power strips and outlets serving nearly all of my electronics, I was feeling pretty good about the level of protection I was providing.

Then, I read a Middle Atlantic Products white paper entitled _The Truth - Power Distribution and Grounding in Residential AV Installation_ (http://www.exactpower.com/elite/wpapers.aspx) which says:

"Surge protection that incorporates all three modes (L-N, L-G and N-G) should only be installed at the service entry... Under no circumstances should "3-mode" protection subsequently be used anywhere inside the house, including at the equipment racks and local convenience receptacles... *this style of protection with a nearby lightning strike will increase the risk of flashover protection and fire!*"​
Now I'm worried that I've created a fire hazard since all of my point of use protection is 3-mode.

Further confusing me is the fact that Eaton specifically recommends a 2-stage surge protection solution and all their indoor products they recommend to be used with their whole-house suppressors all have 3-mode protection.

Anyone here have any idea if these claims are correct? 

Did I just create a major fire hazard by trying to protect my electronics? 

Would I be better off not using point-of-use surge protectors inside at all?

I've got emails in to Eaton and Middle Atlantic Power and will post their responses. Any input from you guys would be appreciated.

Regards,
sga2


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## Guest (Jun 10, 2010)

I've never heard anything like that before. I would be interested to know if their is any truth to that. A few things though, if its a known fire hazard, then how could those devices get a UL certification? Also, if the power of lightning makes it in to the house, I'd think it could be a fire hazard regardless. I think most devices just have fuses in them that pop and thats it. I do know someone who's power box in the yard was hit by lightning and every electronic device in the house got trashed. Nothing caught fire and I don't think anything even smoked.

I'm not going to pretend to be an electrical engineer or anything, but I do car wiring (fuel pumps, stereo's etc) and the whole point of a fuse is to prevent a fire. I'm pretty sure thats the point of the surge protectors too. The stages of protection are to designed to blow and stop the flow of power. Without power, you don't have heat and without heat, you don't have a fire. Maybe I'm missing something.


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## lcaillo (May 2, 2006)

With all due respect to MAS, and that is a great amount of respect, I think they make a serious mistake here and miss a more important point.

The risk of flashover and fire is largely exaggerated, and is dealt with in UL1449 with the requirement for cutoff in units that develop shorts such as occur when an MOV fails catastrophically. The other consideration is the lower probability of levels that can cause such due to the impedance of the wiring by the time you get to a system local surge suppressor.

In the many years that I have worked for dealers that sell surge suppressors that have three way protection, I have never seen such an occurrence, even in systems that were subject to very nearly direct strikes. Virtually all of the system level surge suppressors on the market that are any good have three way protection, btw.

There is much good information on the MAS site, but this is one statement that I think they really misinterpreted the literature when creating.


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## tonyvdb (Sep 5, 2007)

Trust me, I would rather have a surge protector on my system or even whole house than nothing at all. I have seen first hand what a direct or near direct lighting strike can do to a house electrical system and you've got allot more to worry about than just a flash-over if it hits the pole just outside of your service and you have no protection.


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## lcaillo (May 2, 2006)

I agree, Tony. I think this is a perfect example of "baby and bathwater" or "forest and trees."


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## sga2 (Nov 14, 2009)

Thanks, guys, for the input. I feel a little better now. I'm still waiting to hear from MAP (no response yet) and Eaton (my sales rep said she'd not heard of this problem before but has asked their local power quality expert for input). I will post each of their replys if/when I get them.

Regards,
sga2


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## sga2 (Nov 14, 2009)

Sorry for the long silence on this issue. I've heard back from both Eaton and MAP and am posting both of their responses. First, here is Eaton's response. I will follow with MAP's response.

I did not tell them that I was going to be quoting them on any forums, so I left the respondents' names out...

Regards,
sga2


*My Question to Eaton:*

"I recently installed a whole-house surge suppressor system on main panel, CATV, and telco lines (Eaton CHSPULTRA, DCXCAB2, and DHW4PT, respectively). Eaton specifically recommends a 2-stage surge protection solution and all their indoor products they recommend to be used with the above products have 3-mode (L-N, L-G, N-G) protection. While I am not using Eaton point-of-use surge protectors inside, the ones I am using all have 3-mode protection.

I read a white paper entitled “The Truth - Power Distribution and Grounding in Residential AV Installation” (http://www.exactpower.com/wpapers.aspx) which has the statement:
"Surge protection that incorporates all three modes (L-N, L-G and N-G) should only be installed at the service entry... Under no circumstances should "3-mode" protection subsequently be used anywhere inside the house, including at the equipment racks and local convenience receptacles... this style of protection with a nearby lightning strike will increase the risk of flashover protection and fire!”​I’m a mechanical engineer, so this is a bit Greek to me. Is this just marketing propaganda or is there some truth to this? Eaton specifically recommends 2-stage protection with 3-mode protection at both stages (main panel and point-of-use). 

Have I created a fire hazard? Should I get rid of my 3-mode surge protection power strips or replace them with 1-mode (L-N) protection?"

*Eaton Response: * 

“I don’t believe these comments. I have never heard them before and we certainly recommend two levels of surge protection (all connected to ground) throughout power systems and homes. The thing is, if you only connect L-N protection, you take transients from the hot and bring them back to the same system through Neutral – same reason we don’t recommend L-L protection.”


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## sga2 (Nov 14, 2009)

Here is Middle Atlantic Products' reply.

Regards,
sga2


*My Question to MAP:*

"I read your white paper “The Truth - Power Distribution and Grounding in Residential AV Installation” and am curious about the statement:

"Surge protection that incorporates all three modes (L-N, L-G and N-G) should only be installed at the service entry... Under no circumstances should "3-mode" protection subsequently be used anywhere inside the house, including at the equipment racls and local convenience receptacles... this style of protection with a nearby lightning strike will increase the risk of flashover protection and fire!”​
I recently installed a whole-house surge suppressor system on main panel, CATV and telco lines (Eaton CHSPULTRA, DCXCAB2, and DHW4PT, respectively). Eaton specifically recommends a 2-stage surge protection solution and all their indoor products they recommend to be used with the above products have 3-mode protection. While I am not using Eaton point-of-use surge protectors inside, the ones I am using all have 3-mode protection.

I am not an electrical engineer and am not disputing the statement in your white paper. But I’ve not seen this recommendation elsewhere and have asked a couple of EE buddies who have not heard it either. I am concerned that I’ve created a fire hazard and even Eaton - a well established manufacturer of electrical systems - seems to endorse 3-mode protection at both stages (main panel and point-of-use). 

Have I created a fire hazard?

Should I remove the point-of-use protectors and rely completely on the whole-house surge suppressors?"

*MAP’s Response: * 

"The statement you refer to has been a recent topic of increased scrutiny here. One of the authors, Henry Ott, describes why 3-mode SPD’s are not recommended at the end of branch circuits. But he stops short of any claims about arcing; he just refers to equipment damage." 

"After discussing in depth with him, we have elected to tone-down the candor as the event which would create arcing and flashover is not as common as interconnected equipment damage is.
Here is some information to consider:

The NEC in 2008 (article 285) changed the Code to NOT allow Type-3 SPD’s within 30 feet (conductor feet) from the electrical service panel. Type-3 SPD’s are the 3-mode or “all-mode” protection you describe below. If the clamping voltage of the Type-3 is lower than at the service entrance SPD, then energy will not be shunted in a cascade fashion. So if you installed your 3-mode protector within 30 feet it is not meeting the electrical code.

In code-compliant homes, all bonding to the ground rod(s) occurs at the service entry. At that point, neutral = ground, solidly connected, and no further connection between the two are allowed except with separately derived systems. Any inadvertent wrongful downstream neutral-ground connections are known in the trade as “bootleg grounds”, and can cause many problems including life safety. 

The main bond to the ground rod(s) at the service entry along with a Type-2 SPD ensures any large lightning strike (enough energy to arcover in the main service panel) will be having almost all residual voltage appear on the hot wires, because the vast majority of the energy is diverted to soil earth via the ground rod(s). So this energy on the hot wires goes “looking” for earth soil, and will take all paths to get there, including branch circuit runs. 

Lightning is predominately a high-frequency event (600kHz-1MHz) and as such the resistance of the wires does not matter as much as the impedance. So the 3-mode SPD at the end of a branch circuit has no low impedance path back to soil earth and all the energy the MOV dumps to the safety ground wire system will then attempt to take a fast path back to soil earth through everything that is grounded and attached. 

This is especially true when two separate branch circuits are feeding interconnected equipment and one has a 3-mode SPD. The better way to dissipate and divert this energy is exclusively through the neutral conductor, which by code is not allowed to contact grounded objects except at the main service panel which has a low impedance path to earth soil. Although I disagree with some points this author makes, at high frequency (lightning) the MOV between neutral and ground is a form of bootleg under the right scenario http://www.smartpowersystems.com/New/PDF/Articles/mw ng article.pdf

Series mode branch circuit protectors slow, store, and release the energy found on the hot wire to the neutral wire. This is the best for performance but is costly. http://www.surgex.com/library/10001_WhatisTrueSeriesMode.html

Some other manufacturers, including Middle Atlantic Products http://www.middleatlantic.com/power/main.htm, sell their power strips with MOV’s only between the hot and neutral which are cost-effective and far safer for interconnected equipment than the devices that contain MOV’s between hot and ground.

I hope this information has been useful”


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