TVSS Help - sizing/compatibility

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billiards4me

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I'm a bit of a novice when it comes to TVSS/SPD's. I've installed many, but now I'm working for myself needing to "design" or size/fit a system for a customer of mine.
This is a school, with a MDP for one of the wings : Siemens S4C60ML800ETS, 208Y/120 3ph 4W 800A main lug panel. They would like to put surge protection on this panel, because one of the branch 200A bkrs coming from this panel feeds a sub panel for their computer lab.
Question 1: Would it be recommended to install a TVSS at the MDP AND ALSO at the sub panel in the IT department? Or is the one at the MDP sufficient enough?
Question 2: How would I go about properly sizing and choosing the best TVSS for my situation?
Question 3: Any particular recommendations on best places to price TVSSs out?
Question 4: Is there anything that the experienced TVSS guys think I might not be considering?
Question 5: I've been told that the above MDP panel has been discontinued, and that you can no longer get breakers for it. I don't believe that I won't be able to find what I need, because I'm quite determined.... but any thoughts on that matter?
 
billiards4me said:
I'm a bit of a novice when it comes to TVSS/SPD's. I've installed many, but now I'm working for myself needing to "design" or size/fit a system for a customer of mine.
My understanding is that Ul has discontinued using the term "TVSS" and now calls all such devices type 1,2,3 or 4 SPDs.
This is a school, with a MDP for one of the wings : Siemens S4C60ML800ETS, 208Y/120 3ph 4W 800A main lug panel. They would like to put surge protection on this panel, because one of the branch 200A bkrs coming from this panel feeds a sub panel for their computer lab.
Question 1: Would it be recommended to install a TVSS at the MDP AND ALSO at the sub panel in the IT department? Or is the one at the MDP sufficient enough?
I would put one at both locations if money is not an object.
Question 2: How would I go about properly sizing and choosing the best TVSS for my situation?
There is no sizing really involved. It is now based on the type (1,2,3 or 4). And the type is based on where in the circuit the thing is located. basically, the intent is that the closer to the device you get, the lower the voltage surge that is allowed.
Question 3: Any particular recommendations on best places to price TVSSs out?
Call your local supply house would be my suggestion.
Question 4: Is there anything that the experienced TVSS guys think I might not be considering?
My thinking is that most devices are far more resilient these days than they once were, often incorporating some kind of surge suppression within the devices.
Question 5: I've been told that the above MDP panel has been discontinued, and that you can no longer get breakers for it. I don't believe that I won't be able to find what I need, because I'm quite determined.... but any thoughts on that matter?
What difference does it make? the SPD is tacked on to the MDP. Its not like you are trapped into using a specific brand with that specific panel.
Click to expand...
Personally, I would just call the tech support line for whatever brand you feel comfortable with and get the latest information. Forget getting information like this from the counter guys, or from other ECs and electricians. A lot has changed in the last few years and it is better not to get outdated information.
 
petersonra,
Regarding Question 5, it is my understanding and experience that the SPD requires a circuit breaker to feed/hook it into the system. If that particular panel is discontinued, I'll have a rough time finding a breaker to fit that panel. Or, do they have SPDs that can tap right onto the main lugs of the panel. It is a main lug panel, and I do have spaces available on the multi-tap lugs.
 
billiards4me said:
petersonra,
Regarding Question 5, it is my understanding and experience that the SPD requires a circuit breaker to feed/hook it into the system. If that particular panel is discontinued, I'll have a rough time finding a breaker to fit that panel. Or, do they have SPDs that can tap right onto the main lugs of the panel. It is a main lug panel, and I do have spaces available on the multi-tap lugs.
Click to expand...

Generally it does have to hook to a CB, but it does not have to be one that is designated solely for the SPD. In fact, I think it is a bad idea to do so as you will never know if the CB trips and the only thing hooked to it is the SPD.

In normal operation the SPD draws no current so it can be put on any existing CB and not affect that circuit at all.
 
With SPDs
"you get what you pay for"
"more is better"
From Mike Holt

Put an expensive one, perhaps $1500 Siemens at switch gear, best to get with the equipment and in a bucket if thats the type gear you have, as its critical to minimize lead length
Then put a less expensive one, perhaps $500 at the computer room feeder panel.
 
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