Type 1 TVSS

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RUWired

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Would a type 1 TVSS be permitted to be tapped off a main lug switch board prior to any of the main breakers as in article 285.23 or would i have to follow 285.24 rules.

The main lug switch board is located indoors and is fed from outdoor under ground secondary transformer conductors.( Feeder Conductors)

Rick

285.23 Type 1 SPDs (Surge Arresters).
Type 1 SPDs shall be installed in accordance with 285.23(A) and (B).
(A) Installation. Type 1 SPDs (surge arresters) shall be installed as follows:
(1) Type 1 SPDs (surge arresters) shall be permitted to be connected to the supply side of the service disconnect as permitted in 230.82(4) or
(2) Type 1 SPDs (surge arresters) shall be permitted to be connected as specified in 285.24.

285.24 Type 2 SPDs (TVSSs).
Type 2 SPDs (TVSSs) shall be installed in accordance with 285.24(A) through (C).
(A) Service-Supplied Building or Structure. Type 2 SPDs (TVSSs) shall be connected anywhere on the load side of a service disconnect overcurrent device required in 230.91, unless installed in accordance with 230.82(8).
(B) Feeder-Supplied Building or Structure. Type 2 SPDs (TVSSs) shall be connected at the building or structure anywhere on the load side of the first overcurrent device at the building or structure.
(C) Separately Derived System. The SPD (TVSS) shall be connected on the load side of the first overcurrent device in a separately derived system.
 
Tvss

Tvss

Well when we install a tvss its always not ahead of the main its on the load side of the main breaker on a 4000 amp switchboard .

If not factory installed by Square D we must mount it on section one of that switchboard and it must come with fuse protection internal and be in rigid conduit but thats our spec .

The fuses are located inside the tvss they come with there own fuses and a counter and a remote alarm circuit to give a count of surges and a alarm when a fuse or problem is present Look at the tops of the mains


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If a type 1 can be installed ahead of the main on a service, would it be the same as installing it on the line side of a main lug transformer secondary connection, or would it be a violation of the tap rules.

The way i see it, there is not an exception, but wanted to hear from others because 285.24 doesn't list type 1 installations for feeders.

Rick
 
Type 2s are only on the load side of the main OCP. If you are able to mount a Type 2 at a specific location, you may mount a Type 1 there also.
 
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