240v : Scary start of brew

[BrewdyQuah]

Well, I had an uncomfortable experience last night as I started to get my strike water heated.

I have a 240v/50a system that has been working fine for a the last few years. I typically do a simple BIAB so I only use a single element/vessel, but occasionally I will do a 2 or even 3 vessel system just based upon how I'm feeling.

Last night I decided to hook up my HLT and Kettle elements. Basically BIAB with a heated HLT for a final rinse of the grain.

To start the brew day I hooked up the HLT/element with about 10G of water. All was working fine for about 20 minutes as the water started to reach ~90 degrees. All of a sudden the element power indicator light on my brew box went out, and I could tell power had dropped to the element.

"oh, weird" I thought as I went over to the box and flipped the element switch to off and back to on. But I noticed a faint whiff of smoke coming from the box. I immediately cut power to the whole unit. Opened it up, and noticed that the wiring down from the contactor to the receptacle had all fried.

(I had started cleaning up a bit of the mess/clipped some affected wires before taking this second/third pic)

I'm not sure what happened, or what was at fault. I am just super thankful that nobody was hurt, and nothing started on fire (Thankfully I keep a CO2 extinguisher nearby).

I want to troubleshoot and fix, but I'm right now not sure where to start. I plan on replacing the relay, contactor, receptacle, and all wiring that was affected. The only thing new/changed was the use of a 5500W element that I'm not sure I have really used more than once or twice before. Is it possible to check the working condition of an element to see if that was a possible source of a short?

 

[doug293cz]

I doubt your element was the source of the problem. In overheating cases, which you have, the source is usually very close to the worst heat damage. Here it looks like the overheating occurred at the terminal strip, specifically one, or both of the connections to the black hot wire. Overheating at a connection is almost always due to high contact resistance from a loose connection.

Your contactor is probably still ok. I would replace the melted/burned terminal strips, as well as those adjacent to them that look heat damaged, and any heat damaged wires. Then double check all screw terminals in the panel for tightness.

Brew on

 

[passedpawn]

I doubt your element was the source of the problem. In overheating cases, which you have, the source is usually very close to the worst heat damage. Here it looks like the overheating occurred at the terminal strip, specifically one, or both of the connections to the black hot wire. Overheating at a connection is almost always due to high contact resistance from a loose connection.

Your contactor is probably still ok. I would replace the melted/burned terminal strips, as well as those adjacent to them that look heat damaged, and any heat damaged wires. Then double check all screw terminals in the panel for tightness.

Brew on

Exactly this. Heating/cooling cycles can create loose connections. It's a good idea to occasionally re-tighten everything. I didn't do that and I once had a similar melt.

 

[HighVoltageMan!]

Exactly this. Heating/cooling cycles can create loose connections. It's a good idea to occasionally re-tighten everything. I didn't do that and I once had a similar melt.

Copper can often "creep" or compress with time, especially after building and the finer the wire. The heavier current terminals need to be tightened for the first year or so. Afterward the copper "creep" happens much less. I've had this happen to me, but not to this level. For me, it turned out to be the terminal loosened over time. As mentioned above the terminal resistance increases and produces a great deal of heat.

 

[Jeroen79]

I would also guess it was not tight enough or came loose, if it starts to arc you get that kind of stuff.

 

[sibelman]

All this, and previous similar incidents reported here, have me planning to rebuild my 240V setup to make it easier to periodically check. Even though previous checks have not shown any looseness or other problems.

 

[KyBeer]

As an electrical/mechanical installer for 40 years I have seen this type of damage from loose connedtions and corrosion from dissimilar metal connections. The best way to avoid this type of damage is to check for secure connections. When I built my system befor the first power up I double checked all the lugs.
My system is a 240v 50A system. I installed a hot tub GFI for safety. When the element for the BK failed it tripped. Finished the brew day with the HLT. A GFI breaker is a must for me when I mix water and electricity.

 

[whoaru99]

Some suggest using ferrules on stranded wire going under/into screw clamp type connections.

 

[BrewdyQuah]

Some suggest using ferrules on stranded wire going under/into screw clamp type connections.

In some of my research on repairing the system, I came across this same recommendation. Seems like not everyone does this, but it is a best practice. And in my case, could have potentially prevented the short.

Appreciate everyone's feedback. Helped build back some of the confidence I lost in the brew panel (and my ability to handle it). Thanks!

 

[passedpawn]

As an electrical/mechanical installer for 40 years I have seen this type of damage from loose connedtions and corrosion from dissimilar metal connections. The best way to avoid this type of damage is to check for secure connections. When I built my system befor the first power up I double checked all the lugs.
My system is a 240v 50A system. I installed a hot tub GFI for safety. When the element for the BK failed it tripped. Finished the brew day with the HLT. A GFI breaker is a must for me when I mix water and electricity.

I agree on a GFI, but it would not have prevented the issue in this thread.