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SunSynk - Why an MCB on the Surge Protector earth wire


PowerUser
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I have noticed something in the SunSynk installation manual which I cannot find being discussed anywhere previously. On page 23, under the recommendation for a Surge Protector, there is an MCB on the earth wire of the surge protector. Why is that necessary? What are the reasons behind it and what rating that MCB needs to be? See attached picture below:

sunsynk-earth-mcb.thumb.PNG.d589bd0a6af0151e91f3b21e8ad3d148.PNG

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1 hour ago, PowerUser said:

I have noticed something in the SunSynk installation manual which I cannot find being discussed anywhere previously. On page 23, under the recommendation for a Surge Protector, there is an MCB on the earth wire of the surge protector. Why is that necessary? What are the reasons behind it and what rating that MCB needs to be? See attached picture below:

sunsynk-earth-mcb.thumb.PNG.d589bd0a6af0151e91f3b21e8ad3d148.PNG

So in normal operation the SPD (At end of life should lock out and just not function) but if damaged or if its capabilities are exceeded it could create a dead short to earth, therefore the breaker is present to prevent this from happening at the end of life of the SPD. Have seen two professional solar system without these though, so i guess it is commonly disregarded. Maybe someone with more knowledge can expand on this. 

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1 hour ago, Basil Katakuzinos said:

So in normal operation the SPD (At end of life should lock out and just not function) but if damaged or if its capabilities are exceeded it could create a dead short to earth, therefore the breaker is present to prevent this from happening at the end of life of the SPD. Have seen two professional solar system without these though, so i guess it is commonly disregarded. Maybe someone with more knowledge can expand on this. 

Also pretty sure it is best practice to put the mcb behind the arrestor and not in front(Possible that this makes no difference though). 

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13 minutes ago, Basil Katakuzinos said:

Also pretty sure it is best practice to put the mcb behind the arrestor and not in front(Possible that this makes no difference though). 

Hi 

It also could be there to protect the surge from pass through to common earth on inverter. But  for me I ran the SPD to an earth spike not to common earth's connected to inverter.

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10 hours ago, John2 said:

Hi 

It also could be there to protect the surge from pass through to common earth on inverter. But  for me I ran the SPD to an earth spike not to common earth's connected to inverter.

I think this is incorrect and goes against the recommendation for SPD installation. Was that done by a qualified electrician or yourself?

See the recommendations below:

A surge protection device (SPD) is correctly wired when:

  1. The protected equipment is equipotentially bonded to the same earth to which the SPD is connected
  2. The SPD and its associated backup protection are connected:
    1. To the network (live wires) and to the main protective bar (PE/PEN) of the board with conductor lengths as short as possible and less than 0.5 m.

Link:

https://electrical-engineering-portal.com/installing-surge-protection-devices

 

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8 hours ago, PowerUser said:

I think this is incorrect and goes against the recommendation for SPD installation. Was that done by a qualified electrician or yourself?

See the recommendations below:

A surge protection device (SPD) is correctly wired when:

  1. The protected equipment is equipotentially bonded to the same earth to which the SPD is connected
  2. The SPD and its associated backup protection are connected:
    1. To the network (live wires) and to the main protective bar (PE/PEN) of the board with conductor lengths as short as possible and less than 0.5 m.

Link:

https://electrical-engineering-portal.com/installing-surge-protection-devices

 

Hi 

Done by myself  , but there is a common point that is the earth rod.

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