UK Are surge protection devices fitted before or after the main switch

[L1Jay1]

Are surge protection devices fitted before or after the main switch

 

[DT1991]

Refering to your LVE board , The incomming tails would terminate into the top of the main switch, so the SPD would be after the main switch.

 

[Strima]

in LVE , SPD is before main switch View attachment 54817



[automerge]1577093974[/automerge]

In the LVE board it’s before main switch, I’m trying to understand this and the way it’s wired, it appears to be wired before the main switch aswell.View attachment 54818

In that style of board the SPD is after the main switch. The meter tails terminate into the top of the main switch.

Ideally on an installation all consumer equipment should be after a main switch to allow for safe isolation. But if the supply was split before the main switch then the SPD would have to be before the switch as it is designed to protect the installation and not just the board..

With a lot of manufacturers if the main installation supply fuse (DNO) is below a certain rating there's no requirement for over-current protection for the SPD.

 

[L1Jay1]

Refering to your LVE board , The incomming tails would terminate into the top of the main switch, so the SPD would be after the main switch.

Sorry I’ve looking at this in the wrong way , the SPD is after the main switch and is pre wired , no need for over current protection , think I’ve got that now
[automerge]1577099221[/automerge]

In that style of board the SPD is after the main switch. The meter tails terminate into the top of the main switch.

Ideally on an installation all consumer equipment should be after a main switch to allow for safe isolation. But if the supply was split before the main switch then the SPD would have to be before the switch as it is designed to protect the installation and not just the board..

With a lot of manufacturers if the main installation supply fuse (DNO) is below a certain rating there's no requirement for over-current protection for the SPD.

When SPD is after main switch and is pre wired , then the is no current flowing through it , am I correct .

 

[SparkyChick]

Sorry I’ve looking at this in the wrong way , the SPD is after the main switch and is pre wired , no need for over current protection , think I’ve got that now
[automerge]1577099221[/automerge]

When SPD is after main switch and is pre wired , then the is no current flowing through it , am I correct .

Whether it needs over current protection is down to the manufacturer.

SPDs are typically metal oxide varistors... At mains voltage these are high resistance and consequently pass no to little current. As the voltage increases, there resistance drops and they conduct more current, dumping the spikes to earth. They may also has discharge arrestors (I think that's what they are called).

The same technology is present in surge arresting extensions which can cause low insulation resistance readings (tip... If an IR test is poor at 500v, if it's good at 250v, it's possibly a surge arrester in circuit).

 

[westward10]

In normal circumstances there is no current flowing through them. They only become active if transient voltages occur diverting them to earth before it can cause possible damage to equipment. In your pic an earth is required from the device to the consumer unit earth terminal.

 

[Strima]

Quite a good explanation from ABB on one type of SPD:

View: https://www.youtube.com/watch?v=33XBMj9jHHc

 

[MJPD29]

in LVE , SPD is before main switch View attachment 54817



[automerge]1577093974[/automerge]

In the LVE board it’s before main switch, I’m trying to understand this and the way it’s wired, it appears to be wired before the main switch aswell.View attachment 54818

Its after the main switch in your picture

 

[davesparks]

In the LVE board it’s before main switch, I’m trying to understand this and the way it’s wired, it appears to be wired before the main switch aswell.View attachment 54818

That board looks terrible, the SPD is all off to cock straight out of the box. I'd return that to whence it came and get something fit for purpose.

 

[Baddegg]

CEF special I believe?

 

[multimick]

fitted a few ,there ok ,no problems at all.

 

[UKPN]

Ian 1981 is correct, the devices are after the outgoing terminals of the main switch, in parallel with the busbar. You can see the neutral looped from the outgoing terminal.

 

[Risteard]

CEF special I believe?

Nothing to do with CEF.

 

[L1Jay1]

Nothing to do with CEF.

That’s what I thought

 

[Norah Nabino]

Are surge protection devices fitted before or after the main switch

Before the main switch.

 

[Midwest]

After the main switch, just like everyone else said