A minor electrical mystery....

[oscarvan]

To be solved when I can turn the heat, and everything else off.

The power for the 4 block heaters is 120VAC. There is an outlet in each engine room where two heaters per engine plug in. Wires go to a box with two on/off switches. From there a wire goes up into the helm, and then over to the 120V distribution center.

So far so good.

What I wanted to know was which side they were on. When not heating engines with the block heaters I can plug other heaters into the outlets but I need to do my load balancing.

So I tried every breaker, and none of them turned the outlet off. (Trick: I used an extension cord with a little light in the female plug and ran that up to the helm so I could see it.....) Finally I turned the master breakers off and finally the right side turned it off..... But NONE of the individual breakers.

Hmmmmmm

So I opened up the panel. There are three (newer) cables coming in there. One I know is the 24V charger in the generator room for the bow thruster. One is the block heaters, one I am not sure yet. All of them connected to breakers with their load wire. All the negatives went to a bus bar, not sure where they went from there.

I have a sneaky suspicion that since they are connected to the bus bar behind the breakers they are in fact NOT running through a breaker...... Which is bad, as they are now only protected at the 50A level....

Someone may not have realized how the double pole breakers work....

Gonna have to take a hard look at this, like I said when it's 65ºF outside and I can power everything down...

[jason.erbecker]

Firstly, I have never met a minor electrical mystery! But that is simply because I have always had trouble wrapping my head around the tangled web of theory and copper... I was, however, bright enough to figure out that block heaters would be better on a dedicated circuit with its own breaker based on the amount of power they pull. This realization came to me when I felt the uncomfortably warm extension cord that I was using to plug the block heaters in. In January two (two-outlet) outlet boxes were put into the engine room and wired directly to individual breakers on the main panel. Safety is the number one advantage and the second advantage is, of course, convenience. I can now turn on/off the block heaters without crawling into the engine room.

[brettportzer]

What block heaters are you guys using?

I would love to get a set for my 6-71 naturals...

Diesel Pro has these, but I have read alot about the stick on Wolverine type.

https://dieselpro.com/detroit-diesel...r-for-671.html

[racclarkson@gmail.com]

Those look nice. Been using these for last five years w/o issue. Call them to make sure you get the correct heater (depth wise). I also put them on a dedicated circuit.

[jason.erbecker]

Those look nice. Been using these for last five years w/o issue. Call them to make sure you get the correct heater (depth wise). I also put them on a dedicated circuit.

I use the same ones and have had no issues either. Keeps the engines nice and toasty. It certainly is nice turning the key on a cold morning and having only to look sternly at the start buttons to have the engines fire off in one revolution with no smoke!

[Jammin']

I keep mine on thermostatically controlled switches set to go on at 40* and off at 46* ambient engine room temperature. They never kick on because the engine room never gets down to 40*.

One of the heaters is a dedicated circuit, one has a couple of other things on it, but they respond to their corresponding breaker. One of my little projects next week is to color code all of the outlets to their corresponding breaker. I have them numbered now, but I would like to be able to see at a glance what is on the same circuit and which breaker that is. I'm doing it with different colored electrical tape.

[Byresch]

I keep mine on thermostatically controlled switches set to go on at 40* and off at 46* ambient engine room temperature. They never kick on because the engine room never gets down to 40*.

One of the heaters is a dedicated circuit, one has a couple of other things on it, but they respond to their corresponding breaker. One of my little projects next week is to color code all of the outlets to their corresponding breaker. I have them numbered now, but I would like to be able to see at a glance what is on the same circuit and which breaker that is. I'm doing it with different colored electrical tape.

I always did like you when I lived in MD and DC, the thermostatically controlled switched where wonderful. Although, I had both on dedicated circuits. I'd recommend this setup to anyone.

[jim rosenthal]

I've used the Wolverine pan heaters for years- I have them on my boat engines, also on my diesel standby genset at home. AND on the fuel tank for it. They have been very reliable for me.

[oscarvan]

have the engines fire off in one revolution with no smoke!

And settle into an immediate stable idle without hunting.

[Finalee]

I use the Wolverines also. They allowed me to get another 500 hours out of a worn out 6bta that would not start if temps went below 50. Low draw. Leave them on all year. Be sure to turn them off if using the genny while running.