Old Electrical Metal Conduit
If you have been in your roof space to store your belongings or just had a trades person repairing or maintaining your house you may find metal electrical conduit. What is electrical metal conduit or do you have it in your roof space. Well if your home was built in the 1940s and 50s there is a good chance you still have mental conduit used as your electrical system. If your not the original home owner you will not really know if its there unless you have had an electrician working on your home.
Electrical metal conduit starts from your switchboard and runs around your home to all your light fitting and power points. From my experience I have found it to be more common in roof spaces and occasionally under your floor of the house. Electrical conduit systems are made up of metal pipe with elbow joins and tee connections and have cotton insulated cables running through them. You will find were your metal conduit installation starts from your switch board an earth clamp connected to the pipe. This earth runs from your switchboard earth bar and is then connected to the metal conduit with an earth clip. The earthing on metal conduits is to prevent electrocution.
The reason your metal conduit needs to be earthed is if the cotton cable deteriorates over time and the actual wire touches the pipe then your fuse or circuit breaker will disconnect the electrical circuit and prevent the electrical metal pipe from becoming live and electrocute anyone in your roof space. So this is where the real problem starts.
The Danger Of Metal Conduits
Metal conduit systems rely on the entire conduit system to be earthed and “intact”. If you have bought an old period style 1950s home without the knowledge and history of what electrical work has been installed ether by an electrician or the old handy man than you are taking the risk of not knowing if your electrical mental conduit system is still electrically sound.
What happens over the years of home ownership is that anyone working on the electrical metal conduit needs to disconnect a tee point or elbow to connect a new power point or light point cable and junction to the older wire, thus disconnected the earthing and my not understand how to reconnect the earth once the job has been complete. Most qualified electricians will understand this, its the weekender handy man that will have this issue without knowing what he has done.
So what has happened now is one part of the house has electrical metal conduit without an earth, in the event that cotton cable has been damaged or deteriorates and touches this pipe that conduit now is not earthed and will become a live electrical hazard for anyone that torches it. Another example that could cause metal conduit to disconnect at the joins would be people working and walking around your roof space may be standing on the conduit and over time the conduit joint become loose and pull away.
Energy Safe Victoria have great concerns with metal conduit in older homes and have written a statement,
Energy Safe Victoria has appealed to the electrical trades to help in raising the awareness of property owners and other trades people to the dangers of electrical metallic split conduits. This follows the death of a man in the ceiling space of a property near Geelong in February 2010.
ESV investigators called to the scene said that the electrical wiring in the ceiling space was best described as “a fatality waiting to happen”. There were a number of damaged Vulcanised Indian Rubber (VIR) cables in split conduits and exposed defective connections.
There was no safety switch or RCD installed at this installation. The man’s life could have been saved if an RCD Safety Switch had been installed.
The solution is for a licensed electrician to remove all old VIR cable from your home, and install modern PVC sheathed cables with modern circuit breaker and RCD Safety Switch protection at the switchboard.
In conclusion if you have recently bought a property in the age bracket between
1940 – 1950s or have lived in your home and not had an electrical inspection the time to organize one could not come sooner. For a home electrical inspection consultation you can contact our staff
United Electrical Services P/L and book in an appointment when convenient or simply post you concerns and I will be happy to answerer any questions you may have.
Share your experience and insights in the comments box below.