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philb · 09-14-16, 09:30 PM

Several posts lately have mentioned using mov's for surge and lightning protection on mains voltage.
I thought I'd post my version that's been in use for a while.
The jelly jar is used because it's cheap, it has excellent insulation properties and mov's can have meltdowns when subjected to high amps and voltages.

I put the mov's on half of a 50 cent 5x7 mm board from ebay. The board will hold 2 rows of four mov's.
The wires are 10 awg because I had some short pieces of USE-2 wire after rewiring my solar panels for a lower voltage. 12 AWG THHN wire is my usual choice. The mov legs are wrapped around the 10 awg wire and then soldered. The manufacturer suggest using a heat sink between the mov and the soldering. Apparently excessive heat will destroy them. Imagine that!

The photos show one side of both rows soldered together to a common green taped ground wire. The other two wires can go to a hot wire and neutral for 120 volt circuits. For 240 volt split phase, the wires both go to hot.

The metal lid is drilled and fitted with a 1/2 inch emt screw connection. Then I fill it with silicon. The metal ring and lid
are painted for outdoor use.
I like to use 150 volt RMS version on mains voltage and 84 volts DC version for my 65 volt solar panels.

Keep in mind this device is not UL listed. Insurance companies might frown on them. I don't know. I'd rather explain this to them than explain how one of my building burned.

09-14-16, 09:30 PM	#1
philb Apprentice EcoRenovator Join Date: Nov 2010 Location: Oklahoma City Posts: 155 Thanks: 58 Thanked 17 Times in 14 Posts	Jelly Jar surge protector Several posts lately have mentioned using mov's for surge and lightning protection on mains voltage. I thought I'd post my version that's been in use for a while. The jelly jar is used because it's cheap, it has excellent insulation properties and mov's can have meltdowns when subjected to high amps and voltages. I put the mov's on half of a 50 cent 5x7 mm board from ebay. The board will hold 2 rows of four mov's. The wires are 10 awg because I had some short pieces of USE-2 wire after rewiring my solar panels for a lower voltage. 12 AWG THHN wire is my usual choice. The mov legs are wrapped around the 10 awg wire and then soldered. The manufacturer suggest using a heat sink between the mov and the soldering. Apparently excessive heat will destroy them. Imagine that! The photos show one side of both rows soldered together to a common green taped ground wire. The other two wires can go to a hot wire and neutral for 120 volt circuits. For 240 volt split phase, the wires both go to hot. The metal lid is drilled and fitted with a 1/2 inch emt screw connection. Then I fill it with silicon. The metal ring and lid are painted for outdoor use. I like to use 150 volt RMS version on mains voltage and 84 volts DC version for my 65 volt solar panels. Keep in mind this device is not UL listed. Insurance companies might frown on them. I don't know. I'd rather explain this to them than explain how one of my building burned.