Sorry If this has been a topic before, but I didn't see it in the archives. I was given a basic 1000W inverter for Christmas, and I now want to install it. The manual says I need a shutoff switch. Do I really need one? I wanted to wire it directly to the house battery (with a 150A fuse). I can turn the inverter off manually, so why should I install a shutoff? I didn't want to get fancy with the install, I just want the inverter to run a TV/VCR for the kids or a small microwave to warm up a formula bottle for the little one. I will just plug the appliances into the inverter so no need to fool around with the AC plugs that are currently on the boat. Yes, I know I should have a combined charger/inverter with 2000W and a buch of batteries, but lets keep it simple. The microwave will be on for about 10 seconds at a time and the TV/DVD for 1 and 1/2 hours. We go from marina to marina and get shore power, so I have no issues with using up all my battery power. I have 2 6V Trojan T105 (225 Ah) batteries and a starting battery. Any advice or recommendations would be appreciated. (And do I really need a shutoff switch?) Thanks -Rob
Inverter setup
- Thread starter Rob 1981 Cat 3019642
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Cat30 inverter
Hi Rob; I mounted a 1000W inverter on the bulkhead behing the companion way ladder in the aft berth. It is close to the galley and fairly close to my second battery in my house bank that is under the rear berth. (About 4ft max) I used AWG1 wire for the connections and made up the ends to fit both the battery and inverter. I have a fuse link in the positive line. I utilize it as you propose, by plugging into one of the two 110 outlets in the front of the inverter. It remains off unless we are using it. Have use it for 2 years like that and are satisfied with results. fair winds Dave
Hi Rob; I mounted a 1000W inverter on the bulkhead behing the companion way ladder in the aft berth. It is close to the galley and fairly close to my second battery in my house bank that is under the rear berth. (About 4ft max) I used AWG1 wire for the connections and made up the ends to fit both the battery and inverter. I have a fuse link in the positive line. I utilize it as you propose, by plugging into one of the two 110 outlets in the front of the inverter. It remains off unless we are using it. Have use it for 2 years like that and are satisfied with results. fair winds Dave
Battery Disconnect Switch is Required
1000W Inverter c/w Integral GFCI Receptacle(s) You DO require a battery disconnect switch for the inverter’s DC Positive supply. A 1000W Inverter, will likely be fused at about 80 Amps (not 150A), requiring #6 AWG DC supply cables (#8 AWG might suffice under very specific conditions). An 80A DC Breaker would simultaneously satisfy both the requirements for a disconnect switch and for overcurrent protection (fuse). See Blue Sea Systems “Series 187 MRCB Thermal Circuit Breaker” (replaces the recalled “T1" series) Cat. #7142 Surface Mtd, or #7042 Panel Mtd., or equal. http://www.bluesea.com/dept.asp?d_id=6621&l1=7958&l2=6607 Alternatively, you could use an 80A Fuse #5003 c/w #5124 (or #5006 c/w #5143) and a Mini-Battery Switch (about 3" square,‘On-Off’) #6005. HTH, Gord May
1000W Inverter c/w Integral GFCI Receptacle(s) You DO require a battery disconnect switch for the inverter’s DC Positive supply. A 1000W Inverter, will likely be fused at about 80 Amps (not 150A), requiring #6 AWG DC supply cables (#8 AWG might suffice under very specific conditions). An 80A DC Breaker would simultaneously satisfy both the requirements for a disconnect switch and for overcurrent protection (fuse). See Blue Sea Systems “Series 187 MRCB Thermal Circuit Breaker” (replaces the recalled “T1" series) Cat. #7142 Surface Mtd, or #7042 Panel Mtd., or equal. http://www.bluesea.com/dept.asp?d_id=6621&l1=7958&l2=6607 Alternatively, you could use an 80A Fuse #5003 c/w #5124 (or #5006 c/w #5143) and a Mini-Battery Switch (about 3" square,‘On-Off’) #6005. HTH, Gord May
electrical short
It may not seem apparent why there is a requirement for a shutoff but there are good reasons, the most important being that is the only way to preclude an internal short from becoming a much more serious thing (which a fuse won't prevent). I know you said you prefer to keep it simple but adding a switch isn't that onerous or complex or expensive.
It may not seem apparent why there is a requirement for a shutoff but there are good reasons, the most important being that is the only way to preclude an internal short from becoming a much more serious thing (which a fuse won't prevent). I know you said you prefer to keep it simple but adding a switch isn't that onerous or complex or expensive.
150 amp sounds right to me
for a 1000 watt inverter. That would give you 1800 watts at 12 volts which is about right given the ineffeciency and a little more current for a low voltage situation. I like the idea of keeping at least some of the inverter powered outlets separate from the shore power fed ones. I had an inverter charger which went out on me once and it was wired so that I had no 110 volts at the dock when that happened so no lights, no batteries, no nothing until I ran a power cord.
for a 1000 watt inverter. That would give you 1800 watts at 12 volts which is about right given the ineffeciency and a little more current for a low voltage situation. I like the idea of keeping at least some of the inverter powered outlets separate from the shore power fed ones. I had an inverter charger which went out on me once and it was wired so that I had no 110 volts at the dock when that happened so no lights, no batteries, no nothing until I ran a power cord.
Oops
Patrick is right (I was wrong @ 80A) in recommending a 150A Fuse for a typical 1000W Inverter. Of course this will require a 150 A Breaker (Blue Sea #7148) and minimum #4 AWG DC feeder cable. I believe we are talking about a basic Inverter c/w Integral Outlets, not wired into the boat's AC system.
Patrick is right (I was wrong @ 80A) in recommending a 150A Fuse for a typical 1000W Inverter. Of course this will require a 150 A Breaker (Blue Sea #7148) and minimum #4 AWG DC feeder cable. I believe we are talking about a basic Inverter c/w Integral Outlets, not wired into the boat's AC system.
Switch!
The only reason I consider having a switch is to cut power to the unit when the boat is unattended. In case of a short, the fuse will break the cuircuit but not before those massive gauge cables heat up to some degree.
The only reason I consider having a switch is to cut power to the unit when the boat is unattended. In case of a short, the fuse will break the cuircuit but not before those massive gauge cables heat up to some degree.
Disconnect Switches
Commonly, shipboard devices like windlasses and inverters are installed with fuse protection in their DC supply lines as is appropriate. What is overlooked many times in these installations, however, is that there may be situations in which the fuse has not blown because the device is not drawing an abnormally large current and yet the device is causing damage that can only be stopped by interrupting the supply current. Consider this: "On a Nordic 53 powerboat, we were steaming up the Straights of Juan de Fuca in patchy fog with large ships passing nearby when we suddenly noticed the AC Voltmeter in the pilothouse fluctuating wildly. Almost simultaneously, the engine room bilge pump lights came on. We knew we had a very unusual problem going on in the engine room and ran down to the engine room deck and through a stateroom that contained the small access door to the engine room. Peering inside we could see substantial flooding and then spotted a stream of hot seawater from the starboard engine exhaust cooling water system spraying directly into the Trace 3000 Watt inverter. The inverter was continuing to produce AC power but was shorting the AC current into the exhaust water stream, potentially energizing the engines and the extensive engine room metalwork with AC current. This is an extremely hazardous situation in a flooded engine room. To add to the problem there was no switch in the inverter DC supply line, only a fuse that would not blow because the inverter, as dangerous as it now was, consumed only its normal current. Because shutting down the ship's entire DC system would be a threat to safety in the shipping channel, we were forced to climb behind the running engine, in a flooded bilge with live AC flowing around us and disable the fuseblock." This dangerous procedure could have been eliminated with a simple disconnect switch located near the engine room door, or better still, a remote disconnect solenoid with a control in the pilothouse.
Commonly, shipboard devices like windlasses and inverters are installed with fuse protection in their DC supply lines as is appropriate. What is overlooked many times in these installations, however, is that there may be situations in which the fuse has not blown because the device is not drawing an abnormally large current and yet the device is causing damage that can only be stopped by interrupting the supply current. Consider this: "On a Nordic 53 powerboat, we were steaming up the Straights of Juan de Fuca in patchy fog with large ships passing nearby when we suddenly noticed the AC Voltmeter in the pilothouse fluctuating wildly. Almost simultaneously, the engine room bilge pump lights came on. We knew we had a very unusual problem going on in the engine room and ran down to the engine room deck and through a stateroom that contained the small access door to the engine room. Peering inside we could see substantial flooding and then spotted a stream of hot seawater from the starboard engine exhaust cooling water system spraying directly into the Trace 3000 Watt inverter. The inverter was continuing to produce AC power but was shorting the AC current into the exhaust water stream, potentially energizing the engines and the extensive engine room metalwork with AC current. This is an extremely hazardous situation in a flooded engine room. To add to the problem there was no switch in the inverter DC supply line, only a fuse that would not blow because the inverter, as dangerous as it now was, consumed only its normal current. Because shutting down the ship's entire DC system would be a threat to safety in the shipping channel, we were forced to climb behind the running engine, in a flooded bilge with live AC flowing around us and disable the fuseblock." This dangerous procedure could have been eliminated with a simple disconnect switch located near the engine room door, or better still, a remote disconnect solenoid with a control in the pilothouse.
Or,
if the inverter was never placed in the engine room. Why do people do that?! These things don't like heat anyway!
if the inverter was never placed in the engine room. Why do people do that?! These things don't like heat anyway!
It's conventional wisdom within the industry
There are numerous subtle scenarios in which a disconnect switch will prove useful. The previous anecdote illustrates one such situation. Hi-Z DC faults would be another case, as would any service & maintenance activities. To list them all would be beyond the scope of a free (expert) opinion posted to a public forum. I normally get paid to write learned treatises. I’ve spent over 40 years learning & thinking about, applying, and writing about electrical issues such as these, and it’s my considered opinion that a disconnect switch is required. ABYC Standards require a disconnect switch.
There are numerous subtle scenarios in which a disconnect switch will prove useful. The previous anecdote illustrates one such situation. Hi-Z DC faults would be another case, as would any service & maintenance activities. To list them all would be beyond the scope of a free (expert) opinion posted to a public forum. I normally get paid to write learned treatises. I’ve spent over 40 years learning & thinking about, applying, and writing about electrical issues such as these, and it’s my considered opinion that a disconnect switch is required. ABYC Standards require a disconnect switch.
And look what I found at Blue Seas
These work up to 300 amps. Sailnet has a 300 amp-er for < $115. But these aren't explosion proof. Keep them away from the batteries.
These work up to 300 amps. Sailnet has a 300 amp-er for < $115. But these aren't explosion proof. Keep them away from the batteries.
Not in the engine room;
I had considered the possibility of a short induced by flooding and had concluded that if the water reached the inverter the boat would be a goner by then anyways. Years ago I had a boat that took in water because of a failed hose and it covered the battery banks and I was surprised to see that the batteries were still putting out juice while underwater but I also learned that the short created by the conductivity of the water between the + and - terminals was of no consequence. I have to be honest and say I never thought about the possibility of anyone installing an inverter in an engine compartment. Live and learn!!!
I had considered the possibility of a short induced by flooding and had concluded that if the water reached the inverter the boat would be a goner by then anyways. Years ago I had a boat that took in water because of a failed hose and it covered the battery banks and I was surprised to see that the batteries were still putting out juice while underwater but I also learned that the short created by the conductivity of the water between the + and - terminals was of no consequence. I have to be honest and say I never thought about the possibility of anyone installing an inverter in an engine compartment. Live and learn!!!
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