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#222246 06/13/23 01:20 PM
Joined: Jan 2005
Posts: 5,422
Likes: 1
Cat Servant
Today I finally installed one.
Despite these being in the NEC for a few years, local supply houses had none in stock -- and couldn't recall ever selling one. After an tended wait, an internet vendor sent me one. A Square D Homeline (HOM2175SB), it cost about $120.
With the decrepit state of the local PoCo grid and the frequency of lightning here, I have wanted to have surge suppression for at least a decade,

Ordering one in the past -- despite their being listed in catalogs and featured in the trade press -- was simply not possible. A request to the supply house invariably resulted in a chat with Square D's engineering department. Such calls always resulted in Square D professing complete ignorance of the topic, and wanting all manner of technical specs such as the impedance of the PoCo transformer and such.

Looking at the instructions I found two matters worthy of comment.
First, Square D is careful to note that their product "may not suppress surges for electronic equipment." Sort of makes me wonder how they know where the electricity is going
Second, there is discussion of what to do with the coiled white wire coming off the device. While the artwork does show the wire landed on the neutral buss, there is no mention of straightening or shortening the wire.

As there is no reset button or trip indicator, I infer that this device simply gives surges a clear path to ground, thereby reducing your equipments' exposure to the surge. Sort of like French unions, the thing just sits around waiting for a strike, then carries on like nothing happened (Sorry, I couldn't resist!)

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Joined: Jul 2004
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I have been doing surge protection since the late 80s when IBM figured out it was cheaper to protect our equipment on the line side of the plug. As a physical planning rep, lightning was most of what I did. Typically there will be an "OK" light on the protector that goes out when it gives up it's life to a transient. Also you really need layers of protection. You want to start chipping away at that surge at the service entrance or main disconnect enclosure but you are still not done.
This is probably what SqD was talking about.
You also want down stream protectors ending with one at the equipment you are worried about. Be sure that protectors catches all inputs. You also want point of entry protectors to all sink back to the grounding electrode system.
As you pointed out, short straight conductors work the best. Start with your grounding electrode system. Be sure that surge has a place to go.

At my house I have a panel protector at the service disconnect panel in the garage, a protector at the house sub panel and protectors on everything I want to keep (computers, TVs etc). I know stuff can still happen but I haven't lost anything to lightning in 30 years and we get flash/bang lightning here about 80-90 days a year. (too close between the flash and bang to measure)

Greg Fretwell

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