Is lightning protection necessary for new buildings?

I am following up with another question:

Can it generally be said that a lightning conductor / lightning protection on a timber frame house (does not) make sense?

What happens if lightning strikes the lightning conductor / a grounded gutter? Can a fire still occur despite the lightning conductor? Is the probability of a lightning strike higher if grounding is present?

Search for Dehn Blitzplaner, everything is in there, including risk assessment, legal regulations, technology, etc.

In my opinion, there is no simple answer. Years ago, we had a semi-detached house with a large walnut tree next to it, which was significantly taller than all the neighboring houses, so we saw no need for a lightning rod. It only took 3 years before lightning struck the neighbor’s house... fire in his attic, almost all our electrical appliances were destroyed. Now we have been living for 20 years in a detached house with a lightning rod and it doesn’t even thunder.

Is the probability of a lightning strike higher if grounding is present?

Even if it were, would your house then be protected… if the electric field strength is so high that it discharges in a lightning strike, then the lightning will probably strike the lightning rod rather than the neighbor's house if it is exactly the same height. But the lightning is not „attracted“.

My electrician explained to me that we have to ground the gutter and the exterior stainless steel chimney via the foundation earth electrode erden müssen.

Whether this electrician belongs to the approximately 20% of the guild who still faithfully hold a VDE subscription selection for electrical engineering crafts, you have to determine yourself. However, even electricians with such a subscription are not lightning protection specialists, and where building regulations do not require a lightning protection system, there is no obligation to ground gutters or downpipes.

Nevertheless, it is sensible to design grounding systems so that they can also be used later for a lightning protection system and to plan connection lugs for a lightning protection system with minimal additional cost during the installation of the grounding system. In that case, the downpipes should also be connected with the connection lugs.

The solar system on the roof can then also be grounded via the gutter. The argument: In the event of a lightning strike on the solar system/chimney, it is safer if the current is conducted outside the house.

Lightning currents use every path to earth. They distribute almost independently of cross section according to the inductive resistances in loop conductors and will not fulfill the wishful thinking of only discharging on the outside even with exceptionally lightning current-capable connectors.

The company that created the base plate was willing to lay all the connections in the foundation to the outside, but said I should think it over carefully.

Google "DIN 18014:2023-06" and check whether this company even meets the requirements for the installation and documentation of earth electrodes.

It was stated here that grounding is not necessary. On the contrary: if it is grounded, the system must be checked regularly. If this does not happen, there can be trouble with the insurance in case of damage.

Lightning protection systems have no eternal life and must be maintained at intervals. With a lightning protection system, a functional grounding of the module carriers according to DIN VDE 000-712 and DIN EN 62305-3 (VDE 0185-305-3, supplement 5) is mandatory; without a lightning protection system, contrary to frequent incorrect statements, it is not.

IF a functional grounding is installed, then according to German standards it must be routed directly adjacent to the photovoltaic lines, which excludes the option with the downpipe.

See the DEHN lightning planner for this. Even with at least 2 down conductors for a lightning protection system, functional grounding conductors of at least 6 mm² (separation distance maintained) or 16 mm² Cu (separation distance not maintained) are normatively required.

Even if that were the case, your house would then be protected… if the electric field strength is so high that it discharges in a lightning strike, the lightning will probably strike the lightning rod rather than the neighbor’s house if it is exactly the same height. But lightning is not “attracted.”

In all previous studies of lightning damage, NO increased local strike frequency has been found due to lightning protection systems, photovoltaic systems, and/or antenna systems of typical building heights.

However, lightning preferentially strikes edges, corners, and especially points with high field line concentration, which is why masts of terrestrial roof antennas act as unwanted lightning receptors. Where lightning preferentially strikes can be determined quite accurately using the scientific lightning sphere method.

Direct strikes are objectively rare, and anyone who wants to protect their house or individual roof structures against them must guard against this with separate air-termination devices according to the state of the art. Direct grounding of antennas or photovoltaic systems with commendable external down conductors and the rarely found lightning current certified connectors and HES with tension clamps cannot prevent partial lightning currents from coupling into the systems during direct strikes and potentially destroying sensitive electronics.

A lightning protection system requires a functional grounding of the module carriers according to DIN VDE 000-712 and DIN EN 62305-3 (VDE 0185-305-3, Supplement 5); without a lightning protection system, however, this is not mandatory contrary to frequent false statements.

Typo noticed too late, it should have been DIN VDE 0100-712.