Location of surge suppressors

[cdonal0527]

I am looking for the NEC Code regarding the location of surge suppressors. I was under the impression that they should not be installed within the protected equipment panel(s). Is this a part of the NEC, another Code, the manufacturer's specification, or a myth?

Can anyone point me to the Code reference?

Thanks,
Chris Donaldson

 

[tom baker]

Re: Location of surge suppressors

Article 285-Transient Voltage Surge Supressors, is new for the 2002 NEC. The UL listing for TVSS is UL 1449 2 edition.

 

[hurk27]

Re: Location of surge suppressors

Chris
One of the best places for them is in the main panel as most are required to have leads less than 6" to the main buss. and many manufacture's are now making TVSS units that go in place of a two-pole breaked and just connect to the neutral/grounding bars. maybe derreck will show up and give you more info as he is our residance expert on these

Well he knows a darn lot more about them than I do. LOL

[ February 10, 2004, 01:31 AM: Message edited by: hurk27 ]

 

[ron]

Re: Location of surge suppressors

The issue regarding TVSS' installed within panels is a Listing issue. If UL, NRTL or similar lists the equipment with that device as part of the listed devices that can be installed, then it is ok.

For example, I wouldn't attempt to install a Siemens bus mounted TVSS in a GE panel, because the UL Listing for the GE panel doesn't include the Siemens TVSS.

Now I will give way to Derreck.

[ February 10, 2004, 08:36 AM: Message edited by: ron ]

 

[dereckbc]

Re: Location of surge suppressors

My ears are burning. The advice so far is on target, and about all I can offer is to expand on what has already been said. It is a UL issue as Ron stated, rather than a NEC issue. Article 285 specifies the minimum installation requirements and minimum KIAC withstand ratings, not where, when, or if they should be used at all. That is a design issue. If design and TVSS info is what you are after obtain copies of UL 1449 Second Edition, UL 1283 cUL, ANSI/IEEE C62.41 ? 1991, C62.45 ? 1995, NEMA LS-1 ? 1992

For new installations the best solution if the service is single phase and equal to or less than 200-amps is to have the local POCO install a device at the meter socket, or buy your panel(s) with a TVSS device built into the unit. The reason is as Wayne (aka hurk27) stated if the leads are longer than 6 inches the TVSS is rendered useless.

I have not personally used the breaker types as of yet. I suspect these are small class "A" devices with either MOV's or SAD's but not both (size would be limited). I am not sure how difficult it would be to test or monitor them either. However they have possibilities if used as class "A" and possible class "B" devices in sub-panels.

What ever method you use, be sure it is UL-1449 listed with a SVR rating of 330 on a single phase system, and per ANSI/IEEE C62.41-1991 and ANSI/IEEE C62.45-1992. Avoid units with L-G, and N-G modes at the service entrance locations.

[ February 10, 2004, 04:48 PM: Message edited by: dereckbc ]

 

[tom baker]

Re: Location of surge suppressors

In a less technical manner here is how I explain it:
1. With TVSS, you get what you pay for
2. With TVSS, more is better.
3. There is a lot of smoke and mirrors with TVSS.

The TVSS's I install, for a single phase unit, 120/240 volt cost around $300. They are gas tube and MOV's with a monitoring relay in the event protection is lost. They MOV's are 70 mm so this is a pretty robust unit.