Sub-Panel Surge Protection

[Marty Tippin]

I'm looking to add a surge protector to the 100 amp sub-panel in my shop, primarily to protect the electronics in my Powermatic 3520 lathe (3-phase inverter).

A friend recommended this gizmo from Square-D:
http://www.schneider-electric.com/products/us/en/54800-surge-protective-devices-spd/54815-nipple-mounted/61965-type-sdsa1175/

It's about $25 on Amazon and seems priced significantly less than similar "whole house" surge protection devices. Looks easy enough to install and, bearing the Square-D name, I trust that it works as advertised.

Anyone here have experience with this surge protector or similar devices? Recommendations for or against?

[Mike Henderson]

I don't know anything about that surge protector, but it might be more effective to put a surge protector just on the lathe, rather than trying to do surge protection on the whole panel. I don't know a lot about surge protectors, however.

Mike

[Jim Andrew]

This is a good topic, I have a 100 amp panel in my shop, will be watching as well.

[Joe Bradshaw]

I don't have surge protectors in my shop. I make it a habit to unplug any tool(tablesaw, three lathes) that has any kind of electronics.

[Scott T Smith]

I live out in the country in an area where we get a lot of lightning strikes, tree falls onto power lines, etc. Usually we will experience several power outages per year, sometimes there is a surge when the power goes out.

One of my kilns uses a computerized control system that has two PLC's. The PLC's cost around 500 bucks each to replace, and in three years time I replaced three of them - each time following a power surge or power outage.

Five years ago I installed a 200A rated "whole house surge suppressor" on the load center which serves the kiln (and barns, shop, etc), and I have not replaced a PLC since then.

I'm a believer.

[Charles Lent]

You should first check with your power company. Many power companies will come and install a whole house surge protector in your main electric panel free, especially if you have had electrical appliances get damaged by surges in the past.

Charley

[Al Launier]

I live out in the country in an area where we get a lot of lightning strikes, tree falls onto power lines, etc. Usually we will experience several power outages per year, sometimes there is a surge when the power goes out.

One of my kilns uses a computerized control system that has two PLC's. The PLC's cost around 500 bucks each to replace, and in three years time I replaced three of them - each time following a power surge or power outage.

Five years ago I installed a 200A rated "whole house surge suppressor" on the load center which serves the kiln (and barns, shop, etc), and I have not replaced a PLC since then.

I'm a believer.

I also had a "whole house" surge protector installed a number of years ago (~12). Total cost was ~ $100 as I recall, a good protective investment.

[Wes Thom]

I'm looking to add a surge protector to the 100 amp sub-panel in my shop, primarily to protect the electronics in my Powermatic 3520 lathe (3-phase inverter). Others noted what that solution did. But did not say why.

An effective protector does not do protection. It only connects to what does that protection. A sub panel typically does not have an earth ground. Others have protection because that protector connects low impedance (ie 'less than 10 feet') to single point earth ground. A sub panel may not have the all so important earth ground.

Critical is that all incoming wires also connect low impedance (ie 'less than 10 feet') to a common earth electrode. Then a protection 'system' exists.

Protection means you can say where hundreds of thousands of joules harmlessly dissipate. A tool adjacent protector can only (somehow) block or absorb a surge. How does that 2 cm part stop what three miles of sky could not? How does its maybe hundreds of joules absorb hundreds of thousands of joules?

Why would the Schneider be effective? It connects energy 'low impedance' (ie wire without any sharp bends) to single point earth. Protectors are only connecting devices. Verify it connects low impedance (ie ground wire not inside metallic conduit) to what harmlessly absorbs hundreds of thousands of joules. A protector is only as effective as its earth ground.

[david a graham]

I installed the plug in version in both my panels (barn, home) about 6 years ago and feel they work quite well. I have Square D loadcenters so I used the version that plugs in like a breaker. The only items I have lost were on the phone line a DSL modem and router for a lightning strike about 100 feet from both structures. I also have multiple ground rods in the distributions system two at each panel and one by the light at the road.