IMAGE: Wiring rewiring


This weekend and last weekend we successfully carried out demanding operations, consisting of wiring a new main switchboard with a capacity of 200 A, replacing the main circuit breaker, reconnecting the ATS and generator, etc.

As we have already reported, in recent weeks we have implemented long-planned modifications to the main electrical wiring of our datacenter, which has been essentially completely redesigned. The goal was to overdrive them to 200 A (for each phase, so a total of 3x 200 A).

That meant replacing almost everything.

Main circuit breaker replacement – 29.1.

The first adjustments were made on Saturday 29.1. We had to replace the desperately inadequate 32 A main circuit breaker from EON with a new 80 A circuit breaker. This meant a power outage for 1 hour, for which time we also had to disconnect the occupants of the neighbouring building from electricity. Our servers were powered by our generator. Everything went almost as planned, only one server experienced an unplanned outage.

The next step, which will happen in a few months, is to change the main circuit breaker to 200 A, but this means a major reworking of the EON switchboards and running new supply cables into our building. Everything is already arranged and ready with EON, hopefully they will implement it soon.

New main switchboard – 6.2.

A significantly more demanding operation took place on Sunday 6.2. The entire backbone wiring has been reconnected. All the wiring had to be replaced and a new main switchboard was connected. The modifications also affected our generator, which could not be used during this event. Therefore, we rented another generator, which for 1. phase of this event, he was supplying power to the servers.

In phase 1 we disconnected the ATS (automatic transfer switch). It is a device that switches between the power supply from the power plant and the generator depending on the situation. From it, the electricity goes to the main switchboard and then to the UPS and servers. The ATS was relocated, new wiring was brought in from the generator, and a new main switchboard was connected to it. The connection of the new supply from EON came later. Eventually we reconnected the entire server room to a new switchboard, which was now powered only by our generator. This allowed the borrowed generator to be shut down and taken away.

In Phase 2, the goal was to replace the EON feeder cables. First, we also reconnected the upper floor of the building with the offices to the new switchboard. Then the main circuit breaker for the whole building was dropped and a new supply from EON was brought to the ATS.

Everything went exactly as planned, although it was more time consuming than we expected. The most complicated part was working with the new cables, which were incredibly difficult to bend and plug into the tight ATS cabinet. In the end, the whole operation took 7 hours.

As a result, all backbone electrical wiring in our building is now rated at 200 A. In addition, the entire building is backed up by a generator, including the offices. Only the servers are over the UPS, in time the computers in the offices will also be behind a common large UPS, but that will be another time.

The electrical installation work was carried out by IB Solution, s.r.o. (

What happens next

  • In the next few days we still have to connect and start up another 120 kVA UPS. And to this one, gradually reconnect the servers.
  • We’ll be hooking up the air conditioners to the new switchboard soon.
  • We are waiting for EON to replace the supply cables to our building and replace the main circuit breaker to 200 A. Hopefully this will happen in a few weeks, max. a couple of months. This will cover the consumption of about 1300 servers.
  • During the course of this year, work will be carried out to further expand the electrical system, which will include its own substation and more powerful generators. The longest wait will be for EON to run the high voltage cables to our building.