Even if you have decided not to touch the fusebox yourself you should have a good understanding what is going on there. Because you must instruct your electrician what to do for you.
Master Fuses
The power cable coming from your grid provider ends at a point with three big fuses, which usually are rated at 63 amps. Probably you cannot see them because they are covered by insulating material.
Directly behind these fuses sits the official energy meter.
Energy Meter
Many countries require a modern bi-directional counter (left side) if you want to feed energy into the grid. The older energy meters (right side) will have to be replaced by authorized personal. Maybe your electrician can do this for you but it is more likely that only official employees of the grid provider are allowed to replace meters in your country. Check the legal side!
Protected Area
The area with the master fuses and the official energy counter is protected with seals against unauthorized opening. You will NEVER touch this area. Drawing the master fuses requires an isolating footstand, eye protection, gloves and special tools. If an error happens during this action liquid metal could spray directly towards your body!
Energy Entry Point
Directly behind the meter is everything which belongs to your home installation. The cables coming from the energy meter are considered to be the entry point for energy from your perspective. This entry point consists of four wires (the three “phases” and the common neutral wire).
All changes described below happen on your side of the ENTRY POINT.
Usually there is NO SAFE way to work in your area of the fusebox because the wires coming from the energy meter lead directly to a threefold distribution bar where many circuit breakers sit.
To make life easier for you and for the electrician (if you hire one) we recommend to install a master switch directly at the energy entry point.
Master Switch
The master switch must be rated at 63 amps. The lower side is the energy entry point, the upper side is connected to your installation. It does not matter which variant you choose. The advantage of having a master switch is twofold:
- If you have profound knowledge about electricity you might want to make some or all of the changes described below yourself. The only way you can do this at an acceptable risk is to bring the master switch into OFF position. Of course the screws at the lower side of the switch will still have electricity. Once the switch is istalled and its upper side is connected to manifolds, however, the area with the switch can be covered and it is comparatively safe to work behind the switch.
- The master switch provides an easy way to test your backup system because bringing it to the OFF position simulates grid loss.
Manifold block
We recommend to connect manifolds to the “home side” of the master switch.
This will make it easier to link different groups of curcuit breakers to the phases. You need at least two such groups: the regular loads and the critical loads.
Your Energy Meter
The wire leading from the master switch to the manifold block is the place
where you bring in your own energy meter. You can choose to wire it directly
or you can use a variant with inductive sensors.
Residual Current Device (RCD)
You may – or may not – have a special device inside your fusebox which recognizes problems with devices connected to its output wires. Especially for sensitive areas like bathrooms it is recommended (if not obligatory) to have such a protective device. It may save your life in case of an isolation problem with an electric device. If you do not have an RCD inside your fusebox, read more about RCDs in the web and decide whether you want to use the opportunity to install one.
Critical Loads
These are the devices you want to work even if the grid is down. Good examples are:
- everything belonging to your communication infratstructure like internet router, hubs, switches, telephone system, SAT manifolds, SAT receivers, radio, TV, PC, laptop
- the low voltage transformer for your door bell
- security devices like automatic lights, movement detectors, surveillance cameras
- wall sockets where you plug in charging devices for your mobile phone, tablet, mediacal devices are whatever seems important
- the electrical components of your heating system (heting control, furnace, circulation pumps)
- cooling devices (fridges, deep freezers)
- rooms which you feel should have electrical light during off-grid-periods,
especially rooms without windows (toilet room etc) - Ventilation (not necessarily climatization)
- a siphoning plant (if you have one)
- if you have an electrical car: its charging device (wallbox)
- electric door drives (e.g. for your garage)
- electric drives for rolling shutters
The best way to identify your critical loads is to ask yourself what consequences it will have if they are not available for some hours.
You should know which wall sockets will have energy during grid loss.
It is a good idea to mark those wall sockets with a small red (adhesive) dot.
Sometimes you have mobile devices like immersion heaters or electric kettles which you might want to use depending on the energy state of your battery and on the availability of sunlight.
If you have an electric heatpump to prepare warm water or for warming your house we recommend to connect it to the critical loads section. But it could be wise to control the pump manually in case of grid failure. Maybe there is even a way to let it know that energy is scarce at the moment – but this is beyond our discussion here.
Normal (regular) Loads
All other loads are “regular” loads, especially those which consume a lot of energy like washing machine, laundry driers, dish washer, electric kitchen stove, cooking plates, climatization or (worst of all) electric heating and electric water heaters.
Arrange Fuses to blocks
As said before your circuit breakers (CB, fuses, overcurrent protectors) must be assigned to the group of the critical loads or to the regular loads. Therefore you must re-arrange them physicall if cable lengths allow it and you must separate the input sides of the CBs so that the phases of the two groups are separated. The regular devices go to the manifolds, the critical loads must be connected to the “critical loads output” of the backup box of your PV system.
Summary
You should now understand the following diagram. Show it to your electrician.
4 wires AC 380 coming from the grid provider
| | | |
three master fuses |N
| | | |
official energy meter of your grid provider
| | | |
| | | |
| | | |
--- energy entry point ---
| | | |
master switch (to be installed)
| | | |
the manifold (to be installed) |PE
| | | | |
| | | | |
your own energy meter |
(to be installed) |
| | | | |
| | | | |
v v v v v
/----------------------------------------------------\
(1) input side of all fuses (2) grid input cable
for regular devices leading to the
backup box ^
| | | | | |
(3) input side of all fuses | | | | | |
for critical devices BACKUP BOX |
| | | | | | | | | | |
| | | | +--------<----------+ | | | | |
| | | +----------<------------+ | | | |
| | +------------<--------------+ | | |
| +--------------<----------------+ | |
+----------------<------------------+ |
|
|
battery <------> solar inverter <---------+
^
|
solar panels