Do you think it's good idea to install MOV and GDT to each circuit branch in electrical panel ?

Thread Starter

meowsoft

Joined Feb 27, 2021
438
Do you think it's good idea to install MOV and GDT to each circuit branch in electrical panel ?
It my idea safe and feasible ?
 

Reloadron

Joined Jan 15, 2015
6,058
MOV (Metal Oxide Varactor/Varistor)
GDT (Gas Discharge Tube)

Both are used for surge protection in circuits or devices. Would they be practical in for example residential or industrial electrical entry panels? I doubt it primarily because of cost. Here in the US where the NEC (National Electrical Code) applies a recent NEC version mandated GFCI (Ground Fault Circuit Interrupters) in all new construction. It never flew because of added cost. In the case of adding MOV or GDT protection I doubt it would fly either. If for example an entry point were to take a direct lightening hit nothing will prevent damage. I have lived in residential homes for over 70 years and never had a surge great enough to damage anything. Justifying cost, even on a residential panel would be hard to do. Here in my current US residence we bring in 240 VAC 60 Hz split phase power with 200 Amp service. My panel has 40 each of 20 Amp branch circuits. Using MOV or GDT on 40 branch circuits would not be practical. I do have GFCI circuits but not all of them. Outdoor circuits, kitchen and bathroom yes as well as garage but not everything.

Ron
 

Hymie

Joined Mar 30, 2018
991
Having correctly rated MOVs & GDTs will reduce voltage spikes reaching the mains wiring in your home. But as Reloadron says, the benefit may be minimal with electrical equipment designed to withstand expected mains transient voltages.

If you do opt for such an installation, be aware that once ‘fired’, GDTs will conduct until the current drops below a holding level. For this reason, it is vital that an MOV is placed in series with each GDT, such that once the voltage spike passes, the MOV breakdown voltage prevents the GDT from continuing to conduct.

Even so, you should also consider appropriate fusing for the MOV/GDT current path.
 

DickCappels

Joined Aug 21, 2008
7,687
Depends. I lived the first 50 years of my life in an area in which lightning was very rare and really did not feel the need for such protection.

After moving to am area in which lightning strikes are more common I added MOV protected outlets to my house but is 16 years here only once did the electrical system in our village receive a direct lightning strike a lot of damaged was done. I lost a wallwart that supplied USB hubs on one computer, neighbors lost television sets. Fortunately, computers are often well protected against this sort of thing.

Very large MOVs are available and they offer some whole building protection for nearby strikes but the liklihood of such strikes must be weighed against the cost of protection. Do I care if I lose an LED luminaire to a nearby lightning strike? It hasn't happend to me yet and the cost of replacement is low. However the extra layer of protection for computers and my oscilloscope feel it is worth while, as it is inexpensive compared to the potential loss of data and equipment.

For most cases I don't see any net advantage to whole building protection.

I once worked for a computer terminal maker. Once one of our customers experienced a loss of all of their terminals because of a nearby strike to the serial data lines running around their installation. There is more than power to consider.
 

sagor

Joined Mar 10, 2019
479
I use a "whole house" surge protector, wired to the main house panel via a dedicated breaker. That is an "approved" solution. That is enough to suppress surges from reaching all the other wiring. Only exception could be a long run of wiring that may pick up enough of an EMP to cause some surge at the end of the wiring run. However, that would be an extreme case.
For more sensitive devices, like home electronics, put in a well rated surge suppressing power bar near the equipment.
Never wire in your own GDT and MOV into your electrical system, it can be dangerous and may void any home insurance you have. Only use properly certified products or products installed by a licensed electrician.
 
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