Beyond 6 Disconnect w/ TVSS Breaker

[ddcawley]

How's it goin'. I'm new to this web site and forum as of this evening. I'm looking to install a TVSS device on an 800A single phase 120/240V distibution panel. There is no main disconnect on the line side of this panel. It contains 6 200A main breakers which supply subsequent branch panels. My question is, would adding an additional breaker to accomodate the TVSS device violate the "6 disconnect rule"? Incidentally, I'm installing Innovative Technology's PTX-160 at this location. Is anyone familiar with this company/product? I thank you in advance for any info. you can provide.
DDC

 

[charlie]

Re: Beyond 6 Disconnect w/ TVSS Breaker

No, if is not an overcurrent device as well as a TVSS. If it is an OC device, yes, it would be a Code violation since there would now be seven disconnects.

 

[david]

Re: Beyond 6 Disconnect w/ TVSS Breaker

"My question is, would adding an additional breaker to accomodate the TVSS device violate the "6 disconnect rule"? "


charlie:
I hate to contradict anyone on this forum, and there is a smaller group that I have the complete respect for there experience. Charlie my hat is off to you and I always look forward to your comments.

The hand book commentary seems to be saying the exact opposite of your post, ?. If a service disconnect is dedicated to a TVSS unit, it becomes one of the six disconnects permitted in 230.71.?

Further I understand that a service disconnect is coupled with over-current protection for the service conductors , however I did not think a disconnect had to have over current protection to be considered a disconnect.
I believe you are limited to a max of six disconnect and I believe a disconnect installed for a tvss would count as one of the total six.


285.21 Connection.

Handbook commentary:
UL 1449, Safety Standard for Transient Voltage Surge Suppressors, is used to investigate the safety of a TVSS. In accordance with the scope of UL 1449, a TVSS must be installed on the load side of the service disconnect over current protection. If a service disconnect is dedicated to a TVSS unit, it becomes one of the six disconnects permitted in 230.71. Only surge arresters in accordance with Article 280 are permitted to be electrically connected ahead of the service disconnect in accordance with 230.82(3). The requirement for connection on the load side of the first over current protection device in a feeder-supplied structure is necessary due to the exposure of external feeder conductors to a more hostile surge environment such as lightning.

[ August 07, 2003, 01:12 PM: Message edited by: david ]

 

[bob]

Re: Beyond 6 Disconnect w/ TVSS Breaker

David
I may be misreading the posters question but it sounds like he wants to add 7th breaker to his main. If this is true I would have to agree with Charlie. However I would like to ask if it is possible to connect the arrester under and existing breaker assuming it is approved for more that one conductor. The arresters I have seen generally are listed by the mfg under a 30 or 40 amps breaker. The post says that all breakers are 200 amp.

 

[charlie b]

Re: Beyond 6 Disconnect w/ TVSS Breaker

The State of Washington recently adopted the 2002 NEC, along with its own set of related administrative codes. There is an explicit statement in the new codes to the effect that having six disconnect plus a TVSS is acceptable.

 

[charlie]

Re: Beyond 6 Disconnect w/ TVSS Breaker

The handbook states "If a service disconnect is dedicated to a TVSS unit, it becomes one of the six disconnects permitted in 230.71." I agree but you already have six, this would make seven. Am I missing something?

 

[ddcawley]

Re: Beyond 6 Disconnect w/ TVSS Breaker

First, I'd like to thank everyone for their responces. Second, I spoke w/ the sales rep. today to discuss this situation. He feels that the seventh breaker doesn't count since the TVSS draws no current and is installed for the sole purpose of protecting all other circuits in the "unlikely event the tvss should ever fail short."

However, I'm not really convinced. So, I inquired about and orderd a fused TVSS unit that could be installed directly to the buss. He sold me on this but I'm still concerned since there is still essencially no disconnect. Replacement of the unit or fuses must be accomplished live since there is no main 800A disconnect. I have no problem working on it hot but does anyone see a code violation with this second application?

And, while were at it, is there a safety concern regarding more than 6 disconnects? I never really understood the reason for the code.

Also, in responce to Bob's suggestion of adding the leads of the TVSS to an existing breaker, the salesman said you run the risk of damage to the circuits covered by that OCD if the TVSS should fail short. This also doesn't make sence to me. I would think the breaker would simply trip. I also don't know if there is a max OCD size. He did say all I needed was a 30A.

All being said, I am uncomfortable with the vague and ambiguace feed back I've been getting from this "applications engineer." This is my first experience with main tvss equipment and I'm concerned of the reprocutions I could face if the house takes a hit and damage to electronics occurs. This home is complete with Lutron Homeworks lighting, Crestron AV and HVAC control and one very expensive 12 seat movie theater!

So far I've purchaced about 7K worth of TVSS products in an effort to protect every sub-panel. Can someone please ease my mind by confirming my second choice of a fused TVSS or advise me in the right direction?

Thank you,

DDC

 

[david]

Re: Beyond 6 Disconnect w/ TVSS Breaker

Doc:
Its sounds like a catch 32 it seems it would be safer to have a disconnect but their doesn?t seem to be an allowance in the form of an exception in the NEC to allow for this. It would seem to be very dangerous on a live circuit to replace a blown fuse to this devise.

 

[ddcawley]

Re: Beyond 6 Disconnect w/ TVSS Breaker

David,

After re-reading your first reply I feel I truly am stuck. I was thinking the fused TVSS would solve the 6 disconnect problem. Instead, as I now understand it, I'm still in violation by installing the TVSS ahead of the service disconnect. If I only had an 800A main disconnect covering this distribution panel. Then I thought a tvss with it's own integral disconnect would be better for maintenance purposes but it would still be on the line side of this main distribution panel and,I guess, may again count as a seventh disconnect. What to do?

DDC

 

[ddcawley]

Re: Beyond 6 Disconnect w/ TVSS Breaker

Question. If I do go ahead and install this device directly to the bus of this panel, would the addition of a surge arrestor at the CT cabinet alleviate some of the "exposure of a hostile surge environment such as lightning. I've heard the utility company offers some type of surge arrestor. Keep in mind that Innovative Technologies does claim their product can handle direct lightning strikes. Thanks again.

DDC