Electricity Troubleshooting

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Bilge Dweller
Posts: 7
Joined: Mon Dec 24, 2018 1:02 am
Currently located: Turkey

Electricity Troubleshooting

Post by sts07 »

I'm gonna try to explain situation with my limited English knowledge :D . There are two floodlights at foremast and two floodlights at navigation deck on board. Both of floodlight' electricity is supplied through the EMG line. Also we have two more floodlights which are feeded fr main electricity supply but they are unrelated with situation. By the way, we may turn on EMG foremast floodlights and EMG navigation floodlights individually. also we can turn on one of them with main navigation floodlights.However when we try to turn on them at same time, main relay switch of the panel is just cut off. By the way both EMG floodlights have different electricity supply line. Unfortunately there is no ETO on board :D

Big Pete
Engineering Mentor
Posts: 895
Joined: Fri Apr 24, 2009 11:18 pm
Currently located: Solihull, England

Re: Electricity Troubleshooting

Post by Big Pete »

Hi STS07,

I have just noticed that nobody has responded to your post. I am not an Electrician myself, but I will explain how I would approach this problem: -
If the breakers are tripping there are three possibilities: -
A) The incorrect capacity breaker has been fitted.
B) The breakers are operating correctly and the circuit is overloaded.
C) The breakers are faulty and the circuit is operating correctly.

A) Check the Electrical drawings for the original Current rating of the Breaker and compare this with the Breaker that is fitted. Check the Power Rating of the Lights in the original drawings, divide the wattage of the lamps by the Voltage in the circuit to tell you how many Amps the circuit should draw, this should have been less than the rating of the Breaker Fitted. Check the Lamps now fitted in the circuits to see if they are they are the same wattage, and therefore Current, as originally fitted, if the wattage is greater, that could be the cause of the problem
If you have a clamp meter, open the Panel with the breakers in, remove the cover plate and put the clamp meter round ONE of the wires either side of the breakers, watch the current meter when someone switches on the lights and see if the current on the meter is greater than the rated current of the breaker when it trips. If it is the wrong capacity breaker, change it for one of the correct capacity after checking that the Electrical cables and fittings will not overheat under this load.

B) If the Breaker is correct for the Wattage of the Lights and the clamp meter is indicating a greater current is flowing than there should be, then the circuit is being overloaded by a fault. This is most likely an Earth Fault or short circuit, in Deck Light Fittings these problems are often caused by Salt Water getting into Electrical Fittings. Assuming that you have a Multi Meter, with the Breaker in the OFF position, and the switch for each circuit switched on, try measuring the Electrical Resistance between the 2 output wires from the Circuit Breaker to the lights. If the circuit is OK the Resistance of the Circuit should be given by OHM's Law.
Say with a Voltage of 220 Volts a 500 watt Flood light would take a current of 500 Watts /220 Volts = 2.27 Amps
and if a voltage of 220 Volts will drive a current of 2.27 amps through a circuit the resistance should be: 220 Volts / 2.27 Amps = 97 Ohms
If the Resistance is less there is probably a short circuit in the circuit.
If you have a Megga Tester, again with the Breaker off, and the light switched on connect one lead of the Megga to Earth and the other to the two outputs from the Breaker in turn and check the insulation value to Earth, this should be infinite.
If the megga test and or the conductivity results are not what they should be, carry out a close examination of the Flood Lights for signs of Salt, Water and burnt components and clean, repair or replace the flood lights as required.

C) If the breaker is tripping at less than the current it is designed for and everything else is OK replace the breaker with one of the same capacity.

Hope this helps you.

Big Pete.
It is always better to ask a stupid question than to do a stupid thing.

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