Need help on understanding why does the "Black Wire" is always burned/damaged periodically?
It's always being replaced. Is this normal? How can I prevent this from happening.
Thank you!
Electrical – Why does the hot terminal of the extension cord always burn out
electricalwire
Related Solutions
Mira seems to be based in the UK, so I'm assuming a 230V electrical mains.
Just taking the nominal figures for power and voltage gives: 10.8kW / 230V = 46.96A. If you look at the worst case mains voltage (230V - 10% = 207V), you could actually be drawing over 52A.
So, if your shower is drawing as much power as it's rated for (say if the incoming water is very cold, or it's a cold day and you've got the water temperature turned up), a 45A switch is actually underrated for the job it's doing. I'd recommend replacing it with a heftier switch.
Since it's a Ground Fault Circuit Interrupter (GFCI) breaker, it's very likely that you have a ground fault.
GFCIs work by detecting an imbalance in current between the ungrounded (hot), and grounded (neutral) conductors. This is why you only see the trip when the circuit is under load. If there is 0 current flow, the current is balanced.
I'd start by inspecting the receptacle. Turn off the breaker, then open up the box where the receptacle is installed. Look for damage to the receptacle itself, or water/moisture in the box.
For outdoor installations you should always have a weatherproof box, and a cover that is weatherproof even when the receptacle is in use.
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Best Answer
Firstly when a plug or socket overheats you should replace BOTH the plug and the socket and also cut-back any heat-damaged wire. Heat damage can cause buildup of poorly conductive materials on contacts and it can cause loosening of the springs in socket contacts. This means that mating a heat-damaged connector with a good connector can cause the problem to spread.
Secondly breakers don't trip the instant a circuit is overloaded and US regulations allow 15A outlets to be installed on 20A circuits. So it is quite possible to overload an extension cord without tripping a breaker. You really need to pay attention to what loads are connected to a cord rather than just relying on breakers.
Thirdly normal domestic plugs and sockets aren't suitable for use in wet conditions. If you are going to leave wiring outdoors then it really needs to be done in a more suitable manner.
I suspect the reason that the hot fails first is simply that it in a normal american plug the hot contact is smaller than the neutral contact.