This problem needs to have a lot of attribute with, rigorous word answers back and forth: Theoretic will tell, the part accords with the 2.5 square copper cash of GB, can short time carries 20A electricity.
I explain the reason that says so below.
"Part " " GB "GB " GB/T 4706.1-2005 " in regulation, the load current that 2.5 square copper makes wire is worth (current-carrying capacity) for 16A~25A. Apparent, 20A is inside this limits. But the says 2.5 square copper cash that we cannot affirm however can bear the weight of certainly the electric current of 20A.
Because,this is, considered to make an error in the regulation of GB, because this provides medium electricity,the value is an interval. In other words, it is the electrical wiring that accords with GB likewise, a few can bear the weight of 25A electric current, a few can bear the weight of only however 16A electric current -- the product that they are qualification.
Used the error range that GB permits just about, a lot of businessmen use existing high-end technology (small error even 0 errors technology) , make a current-carrying capacity be the wire of 2.5 square copper of 16A directly, the line is needed below the GB in fokelore namely, come with this of utmost reduce cost, get legal chance.
Apparent, the poor electrical wiring below this kind of GB is to cannot bear the weight of of the 20A electric current that says in the title. But the current-carrying capacity that electrical wiring tagged on the electrical wiring nowadays fortunately, although attribute 2.5 square line together, but it is standard line after all still leave poor line, look to know. -- accordingly, we say to have only " part " GB line can bear the weight of 20A electric current.
Of course, so far our discussion limits still is inside GB line. Everybody also saw the 315 evening parties this year, the many building materials that be not mark flows into the market. Be not the electrical wiring of mark, belong to illegal existence, not saying is 20A current-carrying capacity, the 16A that is the difference below GB short of. This kind of line believes to meet what strengthen and superintend strength of consciousness about the branch as user safety increase, exit the market slowly, today we no longer specific discussion.
Although the standard copper cash of 2.5 square can bear the weight of the electric current of 20A, " GB 50217 - cable of 2007 power project designs a standard " in regulation, decorate the BV line inside uses power cable category and BVR line, the electricity that carries for long cannot exceed electrical wiring of rated current-carrying capacity 80% -- in other words, the copper cash of 20A current-carrying capacity, the electric current that bears the weight of for long must not exceed 16A.
Why can you have such regulation? Basically be to prevent circuit to be when overload, electrical wiring cannot bear the weight of the electric current when overload, cause calorific on fire. Because this strives for behavioral time to give the overload in circuit protector, the type selecting of electrical wiring should compare circuit medium practical electric current is big 20% .
