Two 100A incomers , so two Current Transformers ?

[michael8554]

My house has two 100A main fuses.
Effectively one to feed the storage heaters.
And one to feed the CU.
Via an Off-Peak contactor system.

1. So for the Storage Battery Inverter to accurately measure the grid feed in/out, I believe I will need two Current Transformers, one on each of the 100A feeds ?

2. Can I locate the CTs close together and wire them in parallel to one long cable to the single Inverter CT input ?
Or should they be connected to the one Inverter CT input by individual cables all the way ?

3. Researching this, I have also seen suggestions that the CT's should be wired in antiphase to each other, does this make sense ?

Thanks for looking.

 

[Barx]

You sure it's 2 seperate supplies? How many supply meters have you got? Never seen an extra supply for off-peak. Normally 1 supply that splits at the meter. If this is the case then you would just 1 x ct before the meter.

 

[Murdoch]

Op don’t take this the wrong way but It worries me how much solar kit is being bought and installed by novices

We sparks have to jump though hoops, buy books, get assessed, pay CPs membership etc and then people expect free advice on forums

 

[Andy™]

You sure it's 2 seperate supplies? How many supply meters have you got? Never seen an extra supply for off-peak. Normally 1 supply that splits at the meter. If this is the case then you would just 1 x ct before the meter.

seen a fair few with 2 fuses in the service head, 1 meter for normal use and separate meter for off peak. still only 1 incoming cable though

 

[ProDave]

seen a fair few with 2 fuses in the service head, 1 meter for normal use and separate meter for off peak. still only 1 incoming cable though

That's the old white meter system that pre dates economy 7. Are there that many still in use? Most were swapped for E7 which has the benefit of the whole house getting cheap rate at night, where old white meter system only the storage heaters got the cheap rate.

 

[Barx]

Op don’t take this the wrong way but It worries me how much solar kit is being bought and installed by novices

We sparks have to jump though hoops, buy books, get assessed, pay CPs membership etc and then people expect free advice on forums

Been thinking the same for a bit

 

[Barx]

seen a fair few with 2 fuses in the service head, 1 meter for normal use and separate meter for off peak. still only 1 incoming cable though

Interesting. Only ever seen the contactor setup or older meters with 2 lives

 

[Andy™]

That's the old white meter system that pre dates economy 7. Are there that many still in use? Most were swapped for E7 which has the benefit of the whole house getting cheap rate at night, where old white meter system only the storage heaters got the cheap rate.

still see the odd one but most are now a single meter with 2 outputs

and then there are those with the really old mechanical timer for the off peak, which is completely out of sync and gives cheap leccy through the day etc

 

[Murdoch]

Been thinking the same for a bit

I've noticed it on here and other non electrical forums.

Some of the "advice" being given is scary to say the least

 

[johnb2713]

I've noticed it on here and other non electrical forums.

Some of the "advice" being given is scary to say the least

Is that always the way with most topics?

The number of people who watch when you work and comment how easy it all is (it happened to me the last time I used some Wago blocks) I explained "You should never under estimate the complexity of a task when witnessed performed by an expert" He sort of grinned and went away with a puzzled look on his face.

 

[binky]

I've noticed it on here and other non electrical forums.

Some of the "advice" being given is scary to say the least

I've stopped getting involved in other places, it's quite worrying at times and I can't be arsed to argue all night with people who think they know better than me. Batteries particularly worry me, they are potential bombs in the house. We've probably all seen videos of phone batteries that have failed, now scale that up by a thousand....

 

[michael8554]

Thanks for the replies.
Yes there are two (2) 100A fuses.
I'm on Economy 10, and EDF advised me they can't fit a "Smart Meter" for E10.
There is no common point to measure the grid feed in/out.

 

[Phoenix]

I think we would do with a picture

 

[michael8554]

A Two incoming overhead cables
B Two 100Amp fuses
C Off-Peak Timer and Contactor
G 100Amp 30mA RCD, two live outputs, to Storage Heaters and House CU

I was going to clip the CTs to the live cables from G.

 

[Murdoch]

where does the solar AC feed into your system?

 

[michael8554]

The Sunnyboy Solar Inverter is off to the left of the image, the isolator bottom right switches AC from the inverter.

A cable runs from the isolator under the mounting board to H.

The grey cable at D goes from H to a MCB in F.

The AC Battery Inverter is to the left of the Sunnyboy

 

[michael8554]

Have just seen a video that said a CT could be clamped onto the neutral.

There's a single neutral exiting the 100A RCD that appears to be the N for everything ?

 

[johnb2713]

Yes the CT can be clamped to the neutral but the opposite way round.

 

[Geoff1946]

Just wondering, (prepare for daft question), are both incomers on the same phase? Does it matter for what he's doing here.

 

[johnb2713]

Just wondering, (prepare for daft question), are both incomers on the same phase? Does it matter for what he's doing here.

That had crossed my mind too, there would be a danger if not the same phase of 440v kicking about in the domestic environment.