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#85073 - 05/27/03 07:40 AM Article 285 TVSSs
txsparky Offline

Registered: 05/25/01
Posts: 578
Loc: Magnolia,.Texas U.S.A.
How often do you see the TVSS double lugged to the main breaker in a panel? I see it pretty regularly

However, in reading 285.21 it sounds as though that doublelugging is required. More specifically 285.21(A)(2)Feeder Supplied Building or Structure
The transient voltage surge suppressor shall be connected on the load side of the first overcurrent device at the building or structure.

Do some people interpret this a meaning attached to the first overcurrent device or what? I interpret as meaning downstream of the first device.

[This message has been edited by txsparky (edited 05-27-2003).]

2014 / 2011 NEC & Related Books and Study Guides
#85074 - 05/27/03 10:15 AM Re: Article 285 TVSSs
ElectricAL Offline

Registered: 10/10/01
Posts: 615
Loc: Minneapolis, MN USA

The lugs must be listed for more than one conductor. I agree with your concern.

The TVSS works better when its leads are as short as possible / practical and when they are connected as close as possible / practical to the lowest impedance conductors in the assembly.

I've attended a couple presentations by a local power quality consulting group that cleary demonstrates the benefits of not just slapping the TVSS unit in to "get it hooked up". The best TVSS performance is achieved by reconfiguring the existing hardware enough to provide lugs as close to the main service conductors as practical, and to mount the TVSS unit to keep the leads short.
Al Hildenbrand

#85075 - 05/27/03 06:41 PM Re: Article 285 TVSSs
Redsy Offline

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
I,m confused. (Not uncommon).
If it is "double-lugged" to the main, wouldn't it likely be on the line side?


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