Offline-first tools for electricians, marine technicians and off-grid installers. Correct answers on site, with no signal, no account and no ads.为电工、船舶电气技师和离网安装人员做的离线工具。现场就能得到正确答案 —— 不需要信号、不需要账号、没有广告。
Each app solves one problem properly rather than covering a field shallowly. They share the same data sourcing and the same habit of showing the working. 每个 App 只把一个具体问题做透，而不是浅尝辄止地覆盖一大片。它们共享同一套数据来源标准，也共享同一个习惯：把过程显示出来。
Wire sizing, voltage drop and ampacity — offline, on site.线径选型、压降与载流量计算 —— 完全离线，现场可用。
Offline wire sizing, voltage drop and ampacity for 12 V, 24 V and 48 V DC systems.面向 12 V / 24 V / 48 V 直流系统的离线线径选型、压降与载流量计算。
Three things we hold to on every app, because in this line of work a plausible-looking wrong number is worse than no answer. 每一个 App 都守住三条，因为在这类工作里，一个看起来合理的错数字比没有答案更危险。
Every table and formula ships inside the app. It works in a basement, a boat cabin or on a roof with no reception.所有表格和公式都内置在 App 内。地下室、船舱、屋顶 —— 没有信号照样可用。
Reference tables are sourced from published standards, and the edition used is stated inside the app.参考数据来自公开标准，并在 App 内标注所用版本年份。
Every result can be expanded to show the formula and the numbers that went into it, so it can be checked by hand.每个结果都可以展开，显示公式和代入的数值，方便手算复核。
Shijiazhuang Dianhua Technology Co., Ltd. is a small software company focused on a narrow problem: the calculations that electrical work depends on, done quickly and correctly in places where you cannot look things up. Our team combines software engineering with a working knowledge of electrical codes and wiring practice.石家庄点画科技有限公司是一家专注于单一问题的软件公司：电气工作中那些必须算对的计算，要在“没法临时查资料”的环境里快速得出正确结果。我们的团队同时具备软件工程能力和电气规范与布线实务方面的知识。
Most existing tools in this space are web pages that need a connection, or vendor apps that only cover one product. We take the opposite approach: everything ships inside the app, every table is traceable to a published standard, and every answer shows how it was derived.这个领域现有的工具，要么是必须联网的网页，要么是只覆盖自家产品的厂商 App。我们的做法相反：所有数据内置在 App 里，每一张表都能追溯到公开标准，每一个结果都能展开看到推导过程。
