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DIY 240 Volt Relay Backup Switch

Having some form of backup system for power fail is always going to be needed to keep your fish alive no matter where you are if you are using mains power supply.  The following is a breakdown of the parts needed to make a simple backup power fail switch to do just that.    This is not my preference for a backup system as it does not cover you for pump failure.  We will talk about that in the next article. [heading] Relay Backup Switch for Aquaponics and Aquaculture [/heading] Before we get going I strongly recommend you get a qualified electrician to hook one of these up for you if you are dealing with mains power. Above you will see the parts of the DIY Relay Backup Switch and leads.  This Relay Backup Switch is designed to detect if you have lost mains power (240 volt) and switch over to an alternate source of power.  Simply change the relay itself for your particular power in other countries 110 volt etc and obviously the power plug. This particular one is to switch to a 12 volt battery power system if you lose mains power.  That will let you run a 12 volt air pump in the case of mains power failure.  The relay backup switch itself can switch can be used to connect other backup systems, like the starter motor on your generator (my preference). Connecting the relay backup switch is the trickiest part and I will say this again, get your sparky to do this for you because not all relay connections are the same.  Note the image above shows the 12 volt power supply coming in from the left. In the picture above that, the 240 volt power is coming in there but on the lower connection.  It is always handy to get a relay backup switch that has a small light on it to tell you if it is activated or not.  That will make connecting the 240 volt a little easier.  A sparky will sort it no worries. The above picture is an example of what not to do and what happens if you do not have the skills (qualified electrician) to put these together.  They catch on fire!…  This relay backup switch was purchased online and not put together by a qualified electrician.  So give your sparky the plans and ask them to whip you one up that is rated for use around water or outdoors. We asked our sparky to make them up for us for sale (see the very top image) and he said no.  Rightly so!  He explained that he does not know where these boxes will be placed or used and unless he installs them himself, it would put his license/insurance at risk, should someones house burn down as a result of the relay backup switch.  Though he does make a nice one with an indicator light and all. There are other ways to do this without using mains power directly and I will show you those shortly. Regards Paul…

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