How Can I Choose the Wires for Surge Arrester

....wire for low voltage surge arrester....

Do you mean fuse-wire? For arresting current surge ? This is not a normal usage of the terms, perhaps English is not your native language ?

If you mean a voltage surge, you would need to use a Varistor, or an RC network or something.

Firstly, I thank you so much for your responce and sorry for my bad English. You are true, vietnamese is the my native language.

In this case, i want to mention in section of the wire that connects between the busbar phase and terminal of surge arrester.

Thank you so much.

Well, English isn't my native tongue either, so please do not misunderstand whatever i may say.

This surge arrestor that you mention .. who is the manufacturer, is there a model number, any details that you can give would be helpful. i assume you are having a surge arrestor to absorb voltage surges, yes?

There are various manufactures of Low voltage Surge Arrestors and also variety of model numbers. I am mentioning one manufacturer and Model no - Baleastro, PBT-175G, PBT-280G, PBT-500G, PBT-750G and PBT-1000G.

Vinu_Answers Sure Answers

There are literally millions - Elpro, Epcos, ..... (incidentally, Google doesn't recognise "Baleastro" .. is the spelling right?)

That is not the OP's question. He/she hasn't even confirmed that it is a voltage-surge-arrestor.....

British Standard 7671.

The surge arrester is connected between your voltage conductors (bus) and ground, to direct surges such as lightning strikes to ground rather than through your electrical loads. The cables that connect the surge arrester to your system have to be sized to handle that short-time surge current without melting or other thermal damage.

If you know what the possible current will be, then IEEE Std 80-2000 can help you in choosing a conductor size. The tables in section 11.3.2.2 give current ratings of various size conductors at a range of levels of current and duration of time. Since it can be difficult to know the expected value of surge current, many people choose either to size the cable very conservatively (such as #4/0AWG or 100 mm^2), or else will size it per the maximum fault current rating of the system, by which point your overcurrent devices should have tripped. This will probably results in a much larger cable then is really needed.

However, I would expect the surge arrester manufacturer to recommend a cable size to coordinate with the capability of the arrester. Have you checked that? I found the following on a quick Google search on "surge arrester cables" which tells what Schneider Electric uses in their switchgear:

http://www.schneider-electric.us/sites/us/en/support/faq/faq_main.page?page=content&country=US&lang=EN&id=FA130961&redirect=true

Consider the surge current, for the arrester you are installing in the cabinet, as a guide to choosing the wire section.

For human safety reasons the voltage drop between the cabinet and ground must be lower than 50V as far as I remember so you can also consider this factor in choosing wire section.

The surge arrester should protect the panel & all cables / circuits coming into the panel from the outside and all circuits leaving the panel to an external source outside of the building.

The Furse & Dehn lightning protection products have a section that will assist with selecting a SPD that suits your requirements.

Regards

I couldn't pick a post to reply to, so I'm posting to the OP.

I'm a little confused even if no one else is ;-)

The surge arrestor we're talking about here is not generally intended to handle a full lightning stroke. Lightning arrestors somewhere outside the building, are intended to handle those.

This device is aimed at smaller surges that might be the result of a lightning stroke already "arrested" outside the building (but that doesn't level the surge completely), or noise, spikes, surges generated by devices in the workshop.

As such, surely it doesn't need anything like a 4/0 cable. Consider the surge arrestor for something like a PC. It just uses the ground cable in the cable to the device to bleed off the surge. Typically, if you have a cord of #16 wire, the ground wire is also #16.

I'd get the information from the manufacturer, but I'd expect to use a fairly small conductor from the protected bus to the surge device, and from the surge device to ground. Something on the order of the size of the cables feeding the loads from that panel, maybe even smaller.

(What I'm trying to say here is that, for example, 10 loads are each being fed by a #14 feeder (15 amps each), I wouldn't expect to have to use a cable to the surge device and then to ground capable of handling 150 amps. But, I could be wrong.)

But, like I say, see what the manufacturer recommends / requires.

I would refer to the comments from PeterT.

Regards