In Dar es Salaam, Tanzania, residents, electricians, and power‐utility workers tolerate some unofficial forms of modifiying the electrical network, such as unsanctioned reconnections and extensions. These practices, which can also involve theft, bribery, and other illegal activities, both undermine and sustain an increasingly expensive public infrastructure that is in disrepair and subject to routine bureaucratic neglect. But such modifications also have their tacit limits, and people judge as foolish those who have exceeded them. The limits reveal a modal reasoning at work in the relationship among technical systems, urban ethics, and informal economic arrangements. In each of these domains, people use modal reasoning to simultaneously alter and preserve an emergent future. Such reasoning illustrates how infrastructures constitute wholes that emerge from, but are not reducible to, their constituent parts. [infrastructure, electricity, modality, reasoning, urbanism, Dar es Salaam, Tanzania] Dar es salaam, Tanzania, wakazi, mafundi umeme, na wafanyakazi wanaosambaza umeme wanaendekeza kufanya aina za marekebisho ya mifumo ya umeme isiyo rasmi, kwa mfano kuongeza idadi ya watumiaji wa umeme na kuwarudishia huduma ya umeme wale waliokatiwa bila ya kuingia nao mikataba na bila ya idhini kutoka shirika la umeme. Lakini marekebisho haya pia yana ukomo wa ukimya na watu wanawaona wale ambao wamezidi kama vile hawana busara. Ukomo huu unadhihirisha aina ya fikra ya kimfumo katika mahusiano ya nyanja za kiufundi, maadili ya kazi, na mipangilio ya kiuchumi isiyo rasmi. Katika hali hizi nyanja, watu wanatumia fikra za kimfumo kwa wakati huo huo kubadili na kutunza wanachokusudia hapo mbeleni. Fikra hii inaonyesha kwamba miundombuni ni mjumuisho unaotokana na mahusiano ya vipengele mbalimbali na sio vipengele vilivyokaa kipekee. [miundombinu, umeme, mfumo, fikra, mjini, Dar es Salaam, Tanzania] A stockpile of utility poles at a regional office of Tanzania's electric utility, October 14, 2011.