Progressive Industries EMS-HW30C Problem
After an incident at a campground that fried my TV and microwave six years ago, I decided it was time to get some protection. I purchased and installed the Progressive Industries EMS-HW30C Electric...
Forum Discussion
My 2 cents...
In all my years of being an electrical engineer (since 1976), I have never heard of, or seen solder dressed terminations (not splices) in power systems (120 volts and up). Not even once.
Everything I've read about Progressive Industries is that they have excellent customer service - as good as it comes. If they backed away, it must be for a reason.
I have to wonder first, if the lugs that the wires connect to are not designed and approved or listed for solder-dressed conductors.
Second, I *think* with the wires being soldered, when the screw on the lug is tightened, the strands of the wire do not spread out enough to maximize the surface area contact of all the individual strands to the surface of the lug. With a poorer connection, this *could* result in heat.
I have no idea if the lugs in the PI EMS are for copper only or copper/aluminum conductors. I have to wonder if perhaps the solder is not compatible with the material the lugs are made from? The photo below is the contactor in our hard-wired EMS. It has a CSA and CE (for Europe) safety standard label on it. I cannot see any marking for copper only or copper/aluminum. Note that the bottom portion of the lugs are brass, the screw is plated steel and the sides are aluminum. The contact pressure occurs between the brass and steel screw. You would think that the solder on the wires would be compatible with the brass part and steel screw.
Often, a lug for 120 volts, like say for the main lugs in a panel in your home, the lug has a round-ish hole for a conductor. This maximizes the contact surface area between the lug and wire. With the EMS contactor, it has a flat bottom, flat sides and a flat surface on the head of the screw. It would seem to me that this does not allow for optimal contact between the wire and lug, thus allowing for the possibility of a poor connection. Now that I look at it, it would appear that a non-dressed, bare stranded #10 conductor would be what's needed.
I think what may have happened is thermal cycling where due to possible initial inadequate contact between the conductor and lug, the dressed/stranded wires expanded with current flowing through them. The strands could have moved under the higher compressive force in the lugs. Then with no or low current, the wires shrunk making a poorer and higher resistance connection. Repeated over many cycles, the resistance could have increased to a level where significant heat was produced. Just a potential theory.......
With stranded conductors, and more so as the gauge gets larger, it helps to wiggle the wire and re-tighten the lug. This may need to be done several times. This causes the strands to spread out and the result is a better connection. With solder-dressed wires, you can't do this.
One thing you could do is contact CSA and find out details on the certification for the contactor, which should indicate if it is only for bare solid or stranded conductors only. CSA has a very stringent and rigorous testing and certification process, highly recognized as the best in the world. It's highly unlikely that there is a flaw in the design of the contactor. I don't know if there is a part number on it, but maybe PI would tell you? There is a UL label on the exterior of the enclosure but the contactor is marked CSA. I could not tell if there was a part number on it.
I used solid #10 conductors and now that this has come up, I am going to have to check and see if I should be using stranded conductors.
Where does Jayco use solder-dressed wires? Is this on 120 volt or 12 volt wiring?
It is unusual for an EMS to overheat as described. I have read about a few owners coming close to a fire after a lightning strike. Installing some sort of fire protective material might be a good idea, especially if in lightning prone areas. Maybe something like fire rated drywall but you need to maintain ventilation.
In all my years of being an electrical engineer (since 1976), I have never heard of, or seen solder dressed terminations (not splices) in power systems (120 volts and up). Not even once.
Everything I've read about Progressive Industries is that they have excellent customer service - as good as it comes. If they backed away, it must be for a reason.
I have to wonder first, if the lugs that the wires connect to are not designed and approved or listed for solder-dressed conductors.
Second, I *think* with the wires being soldered, when the screw on the lug is tightened, the strands of the wire do not spread out enough to maximize the surface area contact of all the individual strands to the surface of the lug. With a poorer connection, this *could* result in heat.
I have no idea if the lugs in the PI EMS are for copper only or copper/aluminum conductors. I have to wonder if perhaps the solder is not compatible with the material the lugs are made from? The photo below is the contactor in our hard-wired EMS. It has a CSA and CE (for Europe) safety standard label on it. I cannot see any marking for copper only or copper/aluminum. Note that the bottom portion of the lugs are brass, the screw is plated steel and the sides are aluminum. The contact pressure occurs between the brass and steel screw. You would think that the solder on the wires would be compatible with the brass part and steel screw.
Often, a lug for 120 volts, like say for the main lugs in a panel in your home, the lug has a round-ish hole for a conductor. This maximizes the contact surface area between the lug and wire. With the EMS contactor, it has a flat bottom, flat sides and a flat surface on the head of the screw. It would seem to me that this does not allow for optimal contact between the wire and lug, thus allowing for the possibility of a poor connection. Now that I look at it, it would appear that a non-dressed, bare stranded #10 conductor would be what's needed.
I think what may have happened is thermal cycling where due to possible initial inadequate contact between the conductor and lug, the dressed/stranded wires expanded with current flowing through them. The strands could have moved under the higher compressive force in the lugs. Then with no or low current, the wires shrunk making a poorer and higher resistance connection. Repeated over many cycles, the resistance could have increased to a level where significant heat was produced. Just a potential theory.......
With stranded conductors, and more so as the gauge gets larger, it helps to wiggle the wire and re-tighten the lug. This may need to be done several times. This causes the strands to spread out and the result is a better connection. With solder-dressed wires, you can't do this.
One thing you could do is contact CSA and find out details on the certification for the contactor, which should indicate if it is only for bare solid or stranded conductors only. CSA has a very stringent and rigorous testing and certification process, highly recognized as the best in the world. It's highly unlikely that there is a flaw in the design of the contactor. I don't know if there is a part number on it, but maybe PI would tell you? There is a UL label on the exterior of the enclosure but the contactor is marked CSA. I could not tell if there was a part number on it.
I used solid #10 conductors and now that this has come up, I am going to have to check and see if I should be using stranded conductors.
Where does Jayco use solder-dressed wires? Is this on 120 volt or 12 volt wiring?
It is unusual for an EMS to overheat as described. I have read about a few owners coming close to a fire after a lightning strike. Installing some sort of fire protective material might be a good idea, especially if in lightning prone areas. Maybe something like fire rated drywall but you need to maintain ventilation.
