It cannot be assumed a protective device in a consumer unit can be back fed, it definitely could be an issue with an electronic RCBO.

Also if an RCD is required for additional protection it has to be double pole, so a single pole RCBO would not be permissible.

It cannot be assumed a protective device in a consumer unit can be back fed, it definitely could be an issue with an electronic RCBO.

Also if an RCD is required for additional protection it has to be double pole, so a single pole RCBO would not be permissible.

So long as the inverter stops generating when synchronisation with the mains is lost, the question of which way the current is flowing it not so important. When the thermal part or the RCD part causes contacts to open, the inverter side is safe, after the shut off time.

But that will be longer than the breaking time alone so ADS times need a re-visit.

It is much more serious with an inverter capable of island operation, as then the side you may expect to be dead may still be very much alive but just out of phase .

Mike

mapj1 said:

so ADS times need a re-visit

If the cables went all the way back to the origin, they might have to be pretty substantial to meet the minimum Zs; but if they went only part way wouldn't that issue go away? Put another way, you would want the inverter supply to have an R1 + R2 at a comparable value to Ze, which may be difficult to achieve.

Puce we droid disturbances such as induced vollage surges caused 0y lighting.

551.7

Additional requirements for installations where the generating set may operate in

parallel with other sources including systems for distribution of electricity to the

public

551.7.1

When a generating set is used as an additional source of supply in parallel with another source, both

of the following conditions shall be fulfilled:

(i) Protection against thermal effects in accordance with Chapter 42 and protection against overcurrent in

accordance with Chapter 43 shall remain effective in all situations

(ii)

Where an RCD is providing additional protection in accordance with Regulation 415.1 for a circuit

connecting the generator set to the installation, the RCD shall disconnect all live conductors, including the

neutral conductor.

Ref. BS7671:2018:A2:2022 (inserted using scan text)

Puce we droid disturbances such as induced vollage surges caused 0y lighting
Been a digetistin of the Prof Stanley Unwin guide the most homey eletrickery perhaps
?less  muchley  comprehensibible
is all I can say

Mind you some of the regs might as well be also

Mike

 mapj1 

we have to try all the features on this website and our devices such as my Ipad, it would be wrong not to.