TVSS - protect a panel on its own C.B.?

[cppoly]

Article 285 is short. Can a TVSS be connected to protect the entire 42-pole panel if it's connected on its own circuits #37,39,41?

I would think no because wouldn't the TVSS need to be connected ahead of the panel's main?

 

[templdl]

Article 285 is short. Can a TVSS be connected to protect the entire 42-pole panel if it's connected on its own circuits #37,39,41?

I would think no because wouldn't the TVSS need to be connected ahead of the panel's main?

No. The TVSS is to be located as close to the main breaker as possible. Preferably install a 2p breaker in the first spot in the panel for best protection.
Think about it, should you mount the TVSS such that to connect it to the incoming lugs on the line side of the main MB it would violate UL as those lugs aren't list as such. The where else would you connect it? And you are messing with the service entrance listing along with needing suitable OCPD that would not be SE listed.
As such if you reason your thoughts out it's not practical and would be extremely difficult to circumvent the UL/NEC requirement do as you propose.

 

[ceb58]

No. The TVSS is to be located as close to the main breaker as possible. Preferably install a 2p breaker in the first spot in the panel for best protection.
Think about it, should you mount the TVSS such that to connect it to the incoming lugs on the line side of the main MB it would violate UL as those lugs aren't list as such. The where else would you connect it? And you are messing with the service entrance listing along with needing suitable OCPD that would not be SE listed.
As such if you reason your thoughts out it's not practical and would be extremely difficult to circumvent the UL/NEC requirement do as you propose.

IMHO that statement is half true. First it depends on what type it is. If it is a type 1 or 2 it can be ahead of the service disconnect 285.23(A)(1) and 285.24 (A). However it must go through an OCD/disco. before the TVSS. In the communication buildings I look after we have 2 TVSS units. The first unit is tapped ahead of the service disconnect. It then goes to a disconnect and to the TVSS. The second unit is installed as you describe. A 100 amp breaker is installed in the first two slots and goes to the TVSS.
Ether installation you need to keep 285.12 in mind. The conductors need to be as short and as straight a run as possible

 

[cppoly]

So if the TVSS is to protect a 42-pole power panel, then it should be installed on circuits #1,3,5 or #2,4,6 and not on #37,39,41? This information doesn't come from the NEC, but a manufacturer's data sheet?

 

[ceb58]

So if the TVSS is to protect a 42-pole power panel, then it should be installed on circuits #1,3,5 or #2,4,6 and not on #37,39,41? This information doesn't come from the NEC, but a manufacturer's data sheet?

No, the info doesn't come from the NEC. Do not know about mfg. instructions. Different mfg. may have different instructions. Where it dose come from is common sense. Think about it. You are trying to protect the branch circuits. You want the TVSS installed ahead of those circuits not after.