Pros & Cons of splitting incoming tails instead of using CU dedicated feed ?

[danesol]

Just wondering if some of the experts thought there were definite advantages & disadvantages of splitting the incoming tails using a Henley Block etc and supplying a separate dedicated supply to the PV system as opposed to simply using a dedicated MCB/spur within the CU ??

 

[BruceB]

My quick take on it....

Advantages:
- Its an insurance policy so that you cannot be accused of causing any faults that manifest afterwards in the customers existing CU/circuits
- If you want a single method of work then separating the supply will almost always work.
- It makes measuring generation and house load a bit easier.

Disadvantage
- Not always the most economical way of doing it.

Regards
Bruce

 

[moggy1968]

As above really. It takes up more room as well which can be a problem sometimes. I like to keep the PV entirely seperate from the household, having said that, the 2 I have surveyed today have got split load 17th edition boards in, specifically installed previously to allow for PV so we'll be using the unprotected ways on those.
The main thing you absolutely cannot use is an RCD that has other circuits on it which must be protected by an RCD. This and an absence of spare ways is usually the reason we end up putting in a sub board.

 

[Eco Deal]

we always try and go for sep CU NONE RCD IN FULL CONTAINEMENT

learn that when I first strated out on pv put system on same rcd as light durrr bulb popped while guy was on hoilday lost two weeks of sunshine......

 

[screwdriver]

yep 95% of the installs we have done have got separate CUs and no RCD as cables not buried etc.

How many consumer units have you opened up and then wondered how to get the cover back on again????!!!

It avoids any issues with the house owner phoning and saying his power has tripped and you were the last one in.

 

[Eco Deal]

been there done that ....

 

[SolarCity]

learn that when I first strated out on pv put system on same rcd as light durrr bulb popped while guy was on hoilday lost two weeks of sunshine......

Also, inverters should not be installed on shared RCDs as it makes disconnection times problematic.

 

[grandfortune]

to be honest if i went to do a EICR( <--- old Periodic Inspection Report) on a property and found a PV system on the RCD side of a 16th ED or 17th ED board i would code it C1, immediate danger and some one would have to sort it until the consmer unit was re energized.

 

[moggy1968]

hadn't really thought about it, but I would be inclined to agree.

 

[danesol]

yep 95% of the installs we have done have got separate CUs and no RCD as cables not buried etc.

How many consumer units have you opened up and then wondered how to get the cover back on again????!!!

It avoids any issues with the house owner phoning and saying his power has tripped and you were the last one in.

So if say the AC cables are underground say in a garage for example, what RCD in the CU (sub board), do you usually use then ??

 

[moggy1968]

B type