Can anyone tell me what is attached to the main in the attached photo? Diode? Capacitor? What is the purpose?bb
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Learn more about the benefits and compliance details for the DOE's new water heater energy-efficiency standards.
Featured Video
Builder’s Advocate: An Interview With ViewrailHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Not at 1861KB. Shrinkage, John, shrinkage.
PAHS Designer/Builder- Bury it!
Sorry bout that. Try this one.
You have two capaciters acting as a surge supressor for the whole house. They make commercial units, but it seems in this case only the capacitors were used.
Those are MOVs -- metal oxide varistors. They're the heart of standard surge suppressors.
This appears to be a fairly professional installation, judging from the color-coded wire, etc. And the bulges in the shrink wraps suggest that there are fuses inside, something that is needed to prevent a fire. So they should be safe, and possibly effective (they look like fairly beefy units).
What is missing is an indicator that the unit is working. If they take a direct hit then the MOVs sometimes commit suicide, blowing the fuses with them. When this happens, you're no longer "protected".
If there is space in the panel for a 240V breaker, see if you can find a "whole house" surge protector in a 240V breaker form-factor. They are available for several different brands of panels. Install that (with ground connection), then disconnect the existing stuff. This new unit will have a light that tells you it's working.
Note that the "breaker" surge protector instructions may say it should be installed in the top-most slot. While this is ideal, don't let it worry you to put the unit elsewhere in the panel if moving things around to free the top slot would be a big hassle.
For the existing unit, keep in mind that the wires up there are hot even if the breaker just below is tripped. Either use an outside disconnect before cutting or use insulated wire cutters. Cut the wires as close to the connection lugs as possible, then wrap the stubs with electrical tape. (Note that you should probably cut the wires vs removing them from the lugs even if you can disconnect the power, to avoid disturbing those connections.)
Or you can just leave the existing unit, with or without a new surge protector. If you don't feel you need surge protection there's no need to upgrade, and, if feeling the part of the existing units below the round disk it feels like there's a fuse in there (generally a "cartridge fuse" about 1/4" diameter and an inch or so long) then they should be safe to leave.
Dan is correct, those are MOVs
As for the installation, it is close to worthless given the long lead length (high inductance) and the very small MOVs installed. Looks pretty though.
It is also missing one other critical piece.L-L device.
I suspect that it is whole house surge suppressors.