Surge suppressors (not wiring)

Jim Lux James.P.Lux at
Mon Nov 4 10:18:51 PST 2002

At 09:26 AM 11/4/2002 -0800, David Mathog wrote:

> > Jim Lux wrote:
> > > At 10:13 AM 11/1/2002 -0800, David Mathog wrote:
> > >Are my selection criteria unreasonable?  All I want in a strip is:
> > >
> > >6-8 sockets
> > >big MOVs (high joule rating - longer expected lifetime)
> > >metal case with some holes in it (for zeroU mounting,
> > >   I'd accept a plastic case if there was some way to
> > >   mount it in the rack that didn't involve glue or duct tape)
> > >disconnect sockets on MOV failure
> > >15/20A breaker (fuse would be ok).
> >
> >
> > There's a lot more to surge suppression than MOVs and
> > Joule ratings...
> > There was an article in IEEE Spectrum a few years back on
> > this (at least 5 years).
>Absolutely there's more to it than MOVs.  The problem is
>that you basically can't find out much about the guts of
>most commercial surge suppressors, nor can you find any
>relevant test data.  The only recent review I've been able
>to locate was in Consumer Reports (1/2000, p49).  There
>they tested a bunch of strip suppressors for home use.

I'd take a look at  They are a vendor of TVSS...

Their explanatory page: on 
choosing surge suppressors has a description of what was the US Govt 
standardized way of rating these devices (Also, it looks like UL 1449 is 
worth looking at)..

 From what I see (and I'm going to look for the definitive spec from the 
Govt..) it looks like there are three aspects:

Let through voltage (330,400,500)
Reliability (how many surges at what voltage and current)
Mode of Suppression (Line/Neutral, or LN, LGnd, and Ngnd).. (For what it's 
worth, they make a good case for not wanting the "three way, all mode" 

Another mfr website of interest is ProTek ( who make 
high performance transient suppressors for all manner of applications.

I note, from a bit of searching on the web through government procurement 
sites, that the Commercial Item Description (CID) for TVSS, plug in type, 
has been cancelled. (without replacement.. no mention of why)

  It was document number A-A-55818 NOT 1 (date 26 Feb 2002).  The base 
document was issued 9 July 1996 (This might be a linlk: )

(This might also be usable URL: )

The original document says that all the information you would need would be 
found on the UL 1449 "Listing/Classification Page", which would give the 
letthrough voltage, the endurance rating, etc.

The specs also call out IEEE C62.41-1991 (a 121 page document which defines 
the waveforms).

>Good luck though finding a review on something like an EDCO AC-RACK:
>Which is pretty close to my desired products specs (except
>joules, which seems low at 900) and does have the "remove
>load on suppression failure" feature.  So on paper it looks good.
>Be a bit more comforting if some independent group had tested
>it though!

The fact that it is UL1449 listed means that some NRTL (Nationally 
Recognized Testing Laboratory) has tested it, and you should be able to get 
the test report from the MFR...

Interestingly, that page cites IEEE 584, and I can't find IEEE 584..(in 
fact, a search of all IEEE Standards turns up only 4 with the word 
"Transient" in their title, none of which are 
applicable)  Specsmanship?  Maybe the spec covered some other aspect of the 
design? (like the minimum size of the printing on the wire... so they can 
advertise it as "fully designed to meet the intent of IEEE and ANSI 
standard xyz", which is almost meaningless, but sounds real good to a 
unsophisticated buyer)

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