DCMY #92
Well-known member
- Joined
- Jul 22, 2007
- Messages
- 855
- Status
- OWNER - I own a Hatteras Yacht
- Hatteras Model
- 41' DOUBLE CABIN (1962 - 1965)
My neighbor is experiencing odd behavior when connected to shore power. The boat is not a Hatteras. The boat has one 50 amp shore power cord. The boat is configured with two 120 volt busses and nothing on the boat uses 240 volts. Buss No. 1 powers everything including 2 air conditioners. Buss No. 2 powers only 4 air conditioners.
Shore power has run everything, including all 6 A/C units for months with no problems. Last week the 50 amp breaker in the dock pedestal failed (tripped and won't reset). Shore power was connected to the second 50 amp receptacle / breaker in the pedestal and everything ran perfectly (including the A/C units) while a new breaker was ordered.
Yesterday the pedestal breaker was replaced. Now as the 4 A/C units on Buss No. 2 are switched on one at a time the buss voltage progressively drops to 100 volts, then trips the Buss No. 2 main breaker. While Buss No. 2 voltage is dropping, Buss No. 1 voltage progressively increases as load is applied to Buss No. 2. Buss No. 1 voltage peaks about 140 volts with no load on Buss No. 1.
The above occurs now when shore power is provided by the new pedestal receptacle / breaker, and also by the old one on which everything was running perfectly before replacing the pedestal breaker.
Voltage measurements indicate no voltage drop (while loaded) across any of the pedestal terminal lugs, breakers, etc. (both hot leads and neutral). Pedestal wiring is in good condition and terminated exactly as before changing the breaker. Connections on the male shore power cord connector were checked and are tight and clean. Boat side shore power cord connections have not yet been inspected (cord retractor with cord directly lugged to a breaker at the transom).
Everything runs perfectly with no voltage drop on the gen-set. (both busses are paralleled when on the gen-set).
Later today my neighbor will move to another slip with a completely independent shore power feed and see what happens. Hopefully this will point to the problem being on the boat or on the land side of the shore power connection.
If the problem occurs on the alternative shore power pedestal, I would next inspect the main shore power breaker at the transom for voltage drop under load. However, the increase in Buss No. 1 voltage when loading Buss No.2 makes me wonder if this may be a high resistance under load on the neutral rather than on the Buss No. 2 hot lead.
With so many A/C units I would have thought at lease some of them would be 240 volt, but I guess the manufacturer didn't think so.
Any thoughts welcome.
Shore power has run everything, including all 6 A/C units for months with no problems. Last week the 50 amp breaker in the dock pedestal failed (tripped and won't reset). Shore power was connected to the second 50 amp receptacle / breaker in the pedestal and everything ran perfectly (including the A/C units) while a new breaker was ordered.
Yesterday the pedestal breaker was replaced. Now as the 4 A/C units on Buss No. 2 are switched on one at a time the buss voltage progressively drops to 100 volts, then trips the Buss No. 2 main breaker. While Buss No. 2 voltage is dropping, Buss No. 1 voltage progressively increases as load is applied to Buss No. 2. Buss No. 1 voltage peaks about 140 volts with no load on Buss No. 1.
The above occurs now when shore power is provided by the new pedestal receptacle / breaker, and also by the old one on which everything was running perfectly before replacing the pedestal breaker.
Voltage measurements indicate no voltage drop (while loaded) across any of the pedestal terminal lugs, breakers, etc. (both hot leads and neutral). Pedestal wiring is in good condition and terminated exactly as before changing the breaker. Connections on the male shore power cord connector were checked and are tight and clean. Boat side shore power cord connections have not yet been inspected (cord retractor with cord directly lugged to a breaker at the transom).
Everything runs perfectly with no voltage drop on the gen-set. (both busses are paralleled when on the gen-set).
Later today my neighbor will move to another slip with a completely independent shore power feed and see what happens. Hopefully this will point to the problem being on the boat or on the land side of the shore power connection.
If the problem occurs on the alternative shore power pedestal, I would next inspect the main shore power breaker at the transom for voltage drop under load. However, the increase in Buss No. 1 voltage when loading Buss No.2 makes me wonder if this may be a high resistance under load on the neutral rather than on the Buss No. 2 hot lead.
With so many A/C units I would have thought at lease some of them would be 240 volt, but I guess the manufacturer didn't think so.
Any thoughts welcome.
