The American legislative framework is somewhat different from the Russian one - it is more democratic, flexible and stands on a solid foundation - freedom of speech. But it is more interesting to compare the regulatory documentation in the field of electrical engineering, what are its differences and features from the Russian one?
1. Ground wire only!
As the saying goes PUE in section 1.7.121, instead of the ground wire, various metal structures can be used, for example, a steel sleeve in which the conductor is laid. In exactly the same body of electrical laws, but in the USA - National Electric Code, such actions are prohibited. AND Clause 200.02 NEC clearly says that the grounding conductor must not be interrupted by any metal objects.
2. Placing of switchboards
According to the PUE, the placement of switchboards is not standardized, therefore it is permissible to install them in any place convenient for the user. But paragraph 240.24, 2F NEC foreseen this: you cannot place a set of circuit breakers on staircases.
3. Can't use soldering
Clause 2.1.21 of the PUE states that all connections must be made by:
- Crimping.
- Welding.
- Soldering.
- With screw or bolt clamps.
To carry out such types of connections, it is necessary to be guided by additional instructions (which, unfortunately, are not indicated). But National Electric Code, namely section 250.8, B clearly prohibits such a connection method as soldering.
4. Only metal boxes
In this matter, you should refer to 314.3 NEC, which allows the use of boxes made of non-metallic materials only on insulators or in the case of using cables with flexible conductors in rubber or plastic insulation.
The requirement, to put it mildly, is incomprehensible and can carry a hidden meaning only in one context: additional fire safety.
5. What is the smallest section to choose?
To determine the wire, or rather, with the smallest cross-section of its core, just look into table 2.1.1 PUE, and this parameter will be - 1 mm2, which is quite justified, because such a conductor is quite able to withstand a short-term short circuit before the circuit breaker trips.
But Section 310.5 in NEC I do not agree with this statement and sets its own meaning: the minimum cross-section of a copper conductor must be at least 2.5 mm2.
6. Installation of spark protection devices
In this subparagraph, the situation has changed slightly - the Russian rules for the installation of electrical installations have not yet reached this point. In the USA, the installation of spark protection devices and RCDs is considered mandatory, in Russia it is not. Exist GOST IEC 62606-2016, but it is required only for some types of premises.
On the other hand, spark protection devices are very useful in their functionality - they turn off the network at the slightest sparking. And where there are sparks, there is poor contact, and poor contact is a direct harbinger of fire. It will not be superfluous to mention that American spark protection devices are also equipped with RCDs - they carry a double protective function.