PV inverter downstream of TT RCD

[Manizzle]

Hi,

I have an install coming up and it has a 100ma time delay RCD at the supply.

How do I go about installing a PV inverter downstream of this RCD?

 

[Murdoch]

Does the inverter need RCD protection?

 

[Manizzle]

Does the inverter need RCD protection?

No, but the RCD has to stay as it’s a TT supply

 

[binky]

No, but the RCD has to stay as it’s a TT supply

Or RCBO all circuits

 

[Murdoch]

I'm not sure I understand your OP then ..........

 

[runningpiglet]

Hi,

I have an install coming up and it has a 100ma time delay RCD at the supply.

How do I go about installing a PV inverter downstream of this RCD?

Why do you think that might be a problem?

 

[arwooldridge]

100ma TD Works fine on my inverter system on TT.
Whereas 30ma RCD's previously were causing problems.

 

[binky]

100ma TD Works fine on my inverter system on TT.
Whereas 30ma RCD's previously were causing problems.

Most inverters are fine, but some older units, namely ABB needed a 300mA RCD. You don't see those anymore thankfully.

 

[Manizzle]

is it not a problem to have inverters on shared RCDs?
If the RCD trips under a fault situation then the inverter will continue to back feed power for up to 5 seconds.

 

[Murdoch]

If the RCD trips under a fault situation then the inverter will continue to back feed power for up to 5 seconds.

In this case it’s 100ma time delay

 

[binky]

is it not a problem to have inverters on shared RCDs?
If the RCD trips under a fault situation then the inverter will continue to back feed power for up to 5 seconds.

Correct but TT systems usually have 30mA RCDs downstream of the TD unit, its those you don't want to be sharing with the solar. There's some debate about the need for a TD if you have a full board of RCBOs, or all circuits covered by shared RCDs, effectively it's only protecting the meter tails from shorting to a metal board. If said metal board has clamps for the meter tails, and full board of RCBOs, then I believe it can be eliminated.