On Mon 18 May 2009 10:55:40 NZST +1200, Craig Falconer wrote: >> Which reminds me, make sure your house and shed have their earths >> solidly connected! > > Is it worth running an earth wire in the trench ? Or is that going to be > bad later?
I don't see any disadvantage. The house will have its own earth stake, the shed doesn't need one depending on its size, but given a 3-phase supply to the shed (holy bananas, what a shed) I'd be surprised if the sparky wasn't insisting on another stake for the shed. Good idea in any case. If the shed has no own earth, an earth connection in the trench is a must as the house earth stake is used for the shed. Otherwise it's strictly speaking optional and costs money. The issue with house and shed on different earths is that those earths need not have the same potential, which you won't ever notice until you run cables from one to the other. The difference may be big enought to hurt, though shouldn't kill (if it gets that big there's another problem). For data cabling though this can generate additional noise, and that can be a nuisance to deal with. One way of dealing with it is to put an Ethernet switch at the end of each cable on one side, and to treat those cable plugs as potentially charged. As an aside, it's also possible to connect house and shed each to a single phase, but a different one for load balancing. That'll probably give you more noise between the buildings, as well as 380V, not 240V, between the wall outlets. Disclaimer: I'm an electrical engineer, not a sparky. Volker -- Volker Kuhlmann is list0570 with the domain in header http://volker.dnsalias.net/ Please do not CC list postings to me.
