spurs

[ljarrald]

the house used to have storage heaters, they are long gone but the switches to switch them on and off, and the wiring back to the D/B remain.

i am aiming to get most of the house running from batteries charged by a wind turbine, solar panels, and the cheap economy 7 electricity. there is only one socket ring in the house, which is going to be powered from the batteries via an inverter.
but the inverter will trip if i plug something of high load like a hoover in. so here is what i want to do...

i want to use the existing cabling that went to the storage heaters (2.5MM t+e) and replace the isolator switch with a plug socket, and then i want to connect the other end of the cable to the main consumer unit.
that way i can use high loads from the mains, not the batteries.

there are six isolator switches which i plan to change into plug sockets, but they are not on a ring, each one is on its own circuit going all the way back to the D/B.
could i make a ring using junction boxes above the D/B and have each socket as a spur?
i've done a diagram to show what i mean, incase its not obvious, the circles are junction boxes.

thanks in advance!

 

[seasickstevie]

Assuming that your six radials presently go back to a separate (6-way?) consumer unit, and are each fused separately, why not leave them that way and link the 'off-peak' (6-way?) CU tails to your main meter via Henley blocks.

I'm assuming you've done away with the off-peak arrangement with your supplier.

 

[EFLImpudence]

Now, I don't want to be rude but...

...what earthly advantage do you think there would be a in a one metre ring with six ten metre (or whatever) spurs?

The ring final circuit is not a magic solution to electrical problems.
Can you not leave the circuits as they are?
Six 16A radials are 'better' than one 32A ring (even when routed properly).

 

[securespark]

You cannot have a ring final with more spurs on than sockets on the ring.

As EFLI says, you're much better off leaving the sockets on their own radial.

Just fit RCD (if not already fitted).

In fact, if you fit a 20A MCB, you can spur off the socket if required, provided the circuit does not cover more than 50m² (unlikely!)

You could even change the singles for doubles for more versatility.

 

[JohnW2]

You cannot have a ring final with more spurs on than sockets on the ring.

You actually can - provided that you don't feel compelled to follow the 'guidance' of the OSG. BS7671 itself does not forbid it - and I personally see no particular electrical problem with an arrangement such as postulated. However, I totally agree with ....

As EFLI says, you're much better off leaving the sockets on their own radial.

I see no advantage in artificially creating this ring - unless, of course, there is not space for 6 MCBs in the CU (to run them from less than 6 MCBs would be restrictive, since, with the 2.5 mm² cable, no MCB could be >20A).

Kind Regards, John

 

[ljarrald]

thanks for the suggestions. all the cables have already been disconnected from the second consumer unit, the second consumer unit is staying on the economy 7 system because it will be connected to a socket which has a battery charger plugged into it to charge leisure batteries (as mentioned in OP).

the consumer unit only has one space left, which will have the new RCBO for the sockets (unfortunately)

so i'm alright to do it like the diagram then?

 

[JohnW2]

....all the cables have already been disconnected from the second consumer unit, the second consumer unit is staying on the economy 7 system because it will be connected to a socket which has a battery charger plugged into it to charge leisure batteries (as mentioned in OP). ... the consumer unit only has one space left, which will have the new RCBO for the sockets (unfortunately)

I don't know about others, but I'm a bit confused by these two CUs, and what is connected to them. Could you perhaps clarify a bit? Thanks.

Kind Regards, John

 

[ljarrald]

....all the cables have already been disconnected from the second consumer unit, the second consumer unit is staying on the economy 7 system because it will be connected to a socket which has a battery charger plugged into it to charge leisure batteries (as mentioned in OP). ... the consumer unit only has one space left, which will have the new RCBO for the sockets (unfortunately)

I don't know about others, but I'm a bit confused by these two CUs, and what is connected to them. Could you perhaps clarify a bit? Thanks.

Kind Regards, John

basically, there is one consumer unit that is live 24/7 which powers most of the house (lights, cooker, sockets, etc)

and there is another one that is only live from 1AM-8AM. this consumer unit was connected to storage heaters (a long long time ago).

the meter switches the second consumer unit on and off at the set times. and when it does so, it also changes the tariff. electricity costs about 15P per KWH in the daytime, but for the 7 hours when the second consumer unit is live, our electricity only costs 4P Per KWH. (this includes electricity that the main consumer unit uses)

my plan is slightly cheeky. i will charge batteries when the electricity is cheap, and then i will power the lights and main sockets from the batteries in the daytime when electricity is more expensive.

the only things that will be on mains 24/7 is the cooker, shower, fire alarm, and secondary socket cct.

the economy 7 tariff was used to help even loads on the national grid. below is a wikipedia article explaining more.

hope this helps your understanding, you learn something new every day

http://en.wikipedia.org/wiki/Economy_7

 

[seasickstevie]

If the only thing that's being switched on for the off-peak period (the 24/7 board is on also of course) is the battery charger, you'd be best installing a single way board for that, and doing as I said earlier, and putting the former off-peak board on 24/7 also . . . and restoring the radial connections as they were.

 

[JohnW2]

Could you perhaps clarify a bit? Thanks.

basically, there is one consumer unit that is live 24/7 which powers most of the house (lights, cooker, sockets, etc) and there is another one that is only live from 1AM-8AM. this consumer unit was connected to storage heaters (a long long time ago).
the meter switches the second consumer unit on and off at the set times. and when it does so, it also changes the tariff. electricity costs about 15P per KWH in the daytime, but for the 7 hours when the second consumer unit is live, our electricity only costs 4P Per KWH. (this includes electricity that the main consumer unit uses). my plan is slightly cheeky. i will charge batteries when the electricity is cheap, and then i will power the lights and main sockets from the batteries in the daytime when electricity is more expensive. the only things that will be on mains 24/7 is the cooker, shower, fire alarm, and secondary socket cct.

Thanks, but I'm still not totally clear with your planned arrangement. I'm well familiar with E7 (I have it myself).

The concept of your plan is not at all 'cheeky' - it's a very obvious thing to do, and the only reason it is not done widely is because of the problems of efficiency, capital cost and practicalities of storing useful amounts of electricity. If it were easy, practical and cost-effective, everyone would be doing it - and the electricity supply industry would certainly encourage it, since it would, as you say, help to 'even loads' over the 24 hours of a day.

From what you say, it sounds as if you intend to end up with one CU, powered by mains 24/7, serving cooker, shower, fire alarm and the new sockets we are talking about, whilst another CU, serving everything else, will be powered (again 24/7?) from batteries. Is that correct? If so, as SNM has said, it sounds as if the only thing to be switched at the E7 times is the battery charger. Is that also correct? If so, as SNM has also said, it would seem a waste to use a whole CU for just that purpose. What I'm not clear of is why you will have only one spare 'way' in that first (24/7 mains-powered) CU, unless it is only a 4-way CU. If it were, say 10-way or larger, there would presumably be adequate capacity to wire the 6 '24/7 mains' sockets to separate MCBs? Even if it were 8-way, 4 of the socket radials could have seperate MCBs and the final two sharing the last one.

Kind Regards, John

 

[ban-all-sheds]

i will charge batteries when the electricity is cheap, and then i will power the lights and main sockets from the batteries in the daytime when electricity is more expensive.

Err...

Have you done a proper ROI analysis for that?

Given the cost of batteries, their relatively short life, the cost of charger, solar panels, wind turbine & inverter, and the fact that you won't be off-grid for even relatively small loads (a hoover is NOT a large load), will it really pay for itself?