surge suppression in both main and garage sub panel

[awonderfulworld]

I have a surge protection device on my main panel (Siemens SPD4Home - external to the main panel) that is protecting the whole house (or at very least powering the two led bulbs in the suppressor).

The sub panel I put in the garage came in a combo kit that included a plug in style surge suppressor that takes the place of two existing breakers.

The main surge device connects to the main panel via a 20 amp dual pole breaker, a connection to neutral and a ground (neutral and ground are bonded as they should be in the main panel) - the surge device that fits inside the sub panel is a dual pole breaker as well but only has a neutral connector and the neutral and ground are not bonded in the sub panel.

Is there any benefit to the second surge suppressor? If there is a surge underground that got picked up would it even do anything? I have it so it's easy to use (not losing money on it) but can I potentially make it worse for the larger main suppressor?

 

[pattenp]

The second surge suppressor helps more than it hurts. Even with whole house surge suppressors you should still use individual surge protectors at your electronic equipment. The whole house surge protector is not a guaranteed end-all surge protection solution.

 

[rlitman]

Is there any benefit to the second surge suppressor? If there is a surge underground that got picked up would it even do anything? I have it so it's easy to use (not losing money on it) but can I potentially make it worse for the larger main suppressor?

Yes. It has nothing to do with a surge picked up underground. Surge suppression on subpanels prevents something called "ringing".

Let me try to make a "visual" to help explain this for you:
Surges reflect (kind of like an echo) all around a system, and a surge suppressor is like a drain hole that a surge falls into. The problem is that the whole surge will not necessarily fall into the drain, and some parts stick around to bounce around the bigger wires in your system. Putting a secondary TVSS on subpanels helps with this.

 

[Charles (in GA)]

I have a Square D QO2175SB in the top LH of my home breaker panel. Bought it cheap at Home Depot on a clearance several years ago. HD says they are worth about $58 now, I doubt I paid over $20 or so.

In my shop panel (Siemens) I have two individual surge breakers, that each take the place of a single pole breaker. These are a third party manufacture, not Siemens, made by T&L Elect Corp. Don't know if they work or not. When we have electrical storms around here, if I'm home, I unplug everything including the phone system and the cable.

Charles

 

[MTW]

If you want the best protection from voltage spikes and noise, look into your grounding and bonding. The best surge protection available is only as good your grounding and earthing system. All systems within the structure should be well bonded together and connected to a low resistance earth ground. Systems = electric, water, gas, phone, data, cable, antenna, well, metal structures, air. Low resistance earth ground = something more substantial than a driven ground rod with a # 6AWG wire.

More often than not, equipment problems are caused from a difference of voltage potential on the ground reference between the systems, when a fluctuation does occur. Radio and cell towers can deal with direct hits and not skip a beat when done properly.

Most surge protectors are MOV's (metal oxide varistors) They have a limited capacity and are self sacrificial. Repeated low level surges are detrimental to their continued capacity and lifespan. Better protection is gained by paralleling several MOV's for increased current capacity. More is better, rated in joules of energy. The more suppressors you have the more joule capacity you have. But if they don't have a substantial connection to earth to dissipate this energy, they can't really do what they were designed to do, shunt it to ground.

See the attached papers for additional info.
View attachment Grounding It's Not What You Think MHolt.pdf
Lots of good stuff here...
www.solacity.com/Docs/Polyphaser/AC%20and%20DC%20power%20protection%20at%20communications%20sites.PDF
And Here...
http://www.solacity.com/lightning.htm

MTW Ω

 

[wyliesdiesels]

If you want the best protection from voltage spikes and noise, look into your grounding and bonding. The best surge protection available is only as good your grounding and earthing system. All systems within the structure should be well bonded together and connected to a low resistance earth ground. Systems = electric, water, gas, phone, data, cable, antenna, well, metal structures, air. Low resistance earth ground = something more substantial than a driven ground rod with a # 6AWG wire.

More often than not, equipment problems are caused from a difference of voltage potential on the ground reference between the systems, when a fluctuation does occur. Radio and cell towers can deal with direct hits and not skip a beat when done properly.

Most surge protectors are MOV's (metal oxide varistors) They have a limited capacity and are self sacrificial. Repeated low level surges are detrimental to their continued capacity and lifespan. Better protection is gained by paralleling several MOV's for increased current capacity. More is better, rated in joules of energy. The more suppressors you have the more joule capacity you have. But if they don't have a substantial connection to earth to dissipate this energy, they can't really do what they were designed to do, shunt it to ground.

See the attached papers for additional info.
View attachment Grounding It's Not What You Think MHolt.pdf
Lots of good stuff here...
www.solacity.com/Docs/Polyphaser/AC%20and%20DC%20power%20protection%20at%20communications%20sites.PDF
And Here...
http://www.solacity.com/lightning.htm

MTW Ω

Watch out for the user that goes by "westom". He likes to argue over and over about grounding and surges but never backs his points up with links or research papers.

 

[awonderfulworld]

Thanks for the feedback - it sounds like at a minimum it won't hurt to have it in there.

Before going further - an apology - I'm in Canada so our rules are very different from the US. My garage's only source for a ground is the cable running from the 60/120 space main panel, which in turn is grounded to the incoming water pipe - there are no ground rods anywhere (and it's all to code, recently upgraded all panels and passed inspection).

MTW: Understand how having a good ground is usually best, but here in Ontario Canada we can only have the separate building with a ground rod or sent back to the main building:

10-208 Grounding connections for two or more buildings or structures supplied from a single service
Where two or more buildings or structures are supplied from a single service,

(a) the grounded circuit conductor at each of the buildings or structures shall be connected to a grounding electrode and bonded to the non-current-carrying metal parts of the electrical equipment; or

(b) except for buildings housing livestock, the non-current-carrying metal parts of the electrical equipment in or on the building or structure shall be permitted to be bonded to ground by a bonding conductor run with the feeder or branch circuit conductors.

The device I'm wondering about is this one: http://www.amazon.com/dp/B0052MG5K0/?tag=atomicindus08-20

Re-reading the instructions it says it can only be used in a panel with a grounded neutral, which I'm assuming I have since the neutral goes back to the main panel and then ground.

 

[MTW]

.

MTW: Understand how having a good ground is usually best, but here in Ontario Canada we can only have the separate building with a ground rod or sent back to the main building:


The device I'm wondering about is this one: http://www.amazon.com/dp/B0052MG5K0/?tag=atomicindus08-20

Re-reading the instructions it says it can only be used in a panel with a grounded neutral, which I'm assuming I have since the neutral goes back to the main panel and then ground.

I don't work in Canada, and therefore don't know the code there or have a copy, but the rule you posted appears very similar to the NEC.

Quote:
10-208 Grounding connections for two or more buildings or structures supplied from a single service
Where two or more buildings or structures are supplied from a single service,

(a) the grounded circuit conductor (neutral) at each of the buildings or structures shall be connected to a grounding electrode and bonded to the non-current-carrying metal parts of the electrical equipment; or

(b) except for buildings housing livestock, the non-current-carrying metal parts of the electrical equipment in or on the building or structure shall be permitted to be bonded to ground by a bonding conductor run with the feeder or branch circuit conductors.

The way I read this is you must have an electrode at each structure, and nowhere does it say that you are limited to one. Same basic rule as NEC. You might want to check with a different contractor than the one you are using for their interpretation. Earthing electrodes are just like the surge suppressors, the more the merrier, lower earth resistance (impedance) = greater dissipation capability.

As to your suppressor in the link you provided that only has a neutral connection. I took a look at the specs for the device

w3.usa.siemens.com/.../us/en/.../sf-11-sect-01-044-046.pdf

Catalog NumberQSA1515SPD QSA2020SPD
Amperage15 or 20 Amp
Number of Poles(2) 1-Pole Circuit Breakers
Initial Clamping Level 240 Volts
Transient Energy Rating 360 Joules line-to-neutral 720 Joules line-to-line
Transient Suppression500 volts peak, line-to-neutral
Voltage Rating1000 volts peak, line-to-line
Peak Current Rating (impulse)40,000 amperes
Discharge Voltage Characteristic@ 1,500A, 600 volts@ 5,000A, 800 volts(both line-to-neutral)
Discharge Current Withstand Rating 10,000 amperes line-to-neutral
Circuit Breaker Interrupting Rating 10,000A, 120/240V ACListings/Certifications UL, CSA Meets UL 1449 3rd Edition

When using this MOV suppression breaker in a sub-panel in a separate structure, it is a good example of why you want an additional earth electrode at the separate structure.

Consider this, when this device does it's intended function, it shunts the excess energy to the neutral buss. In your sub-panel the neutral buss is isolated. Therefore any surge it shunts will have to travel back to the main panel neutral buss before it can connect and discharge to the earth or transformer. Forcing it back through your feeder neutral could possibly affect devices connected to the main panel neutral. In my opinion a better strategy would be to have a quality earth electrode at the subpanel (remote structure) and a MOV suppressor that could shunt the excess energy to the local earth electrode. This would also save wear and tear on the MOV's at the main panel and point of use units in the main structure.

By the way the PDF link above also list suppression devices for the other services that were mentioned earlier, cable, phone, data. Without connecting the other systems to the earth, you will still be vulnerable to surges from the other systems.

MTW Ω

 

[dledinger]

I don't work in Canada, and therefore don't know the code there or have a copy, but the rule you posted appears very similar to the NEC.

Quote:

(a) the grounded circuit conductor neutral at each of the buildings or structures shall be connected to a grounding electrode and bonded to the non-current-carrying metal parts of the electrical equipment; or

This IS NOT similar to the NEC. In fact, it would be a violation of 250.32.

 

[Eriehunter]

..... very similar to the NEC.

Quote:
10-208 Grounding connections for two or more buildings or structures supplied from a single service
Where two or more buildings or structures are supplied from a single service,

(a) the grounded circuit conductor (neutral) at each of the buildings or structures shall be connected to a grounding electrode and bonded to the non-current-carrying metal parts of the electrical equipment; or

(b) except for buildings housing livestock, the non-current-carrying metal parts of the electrical equipment in or on the building or structure shall be permitted to be bonded to ground by a bonding conductor run with the feeder or branch circuit conductors.

I read this as you have a choice:

neutral with ground rod & bonded metal parts (no egc)

OR

Run a ground wire back to panel that feeds this panel. (ground rod not required by this art.)

 

[MTW]

This thread has gone beyond the original posters question, but for the sake of other lurkers a little more info. Grounding and bonding is probably the most misunderstood subject in the NEC. One of the main reasons is for the terminology used. Equipment grounding conductor, is the dedicated safety ground wire. The grounded conductor, is the neutral (White) or common wire intended for carrying normal circuit currents. Function is totally different but the verbage difference is only ing vs ed. Grounding electrode conductor is the connection from system ground to the earth electrodes.

dledinger
This IS NOT similar to the NEC. In fact, it would be a violation of 250.32.

For new work bonding the grounded conductor (neutral) to the grounding electrode system, would be in violation. New work also requires a equipment grounding conductor (4th wire), along with this is the requirement to connect it to the grounding electrode, and if one is not present to install one.

For existing 3 wire (no equipment grounding conductor) "Exception for installations made in compliance with previous editions of this Code"
It is still permissible to bond the grounded conductor (neutral) and the equipment grounding conductor. It wasn't required at that time to have a grounding electrode at the remote structure but didn't disallow connecting one either. This method was used for many years and is not inherently unsafe but is not best practice today.

Eriehunter
I read this as you have a choice:
neutral with ground rod & bonded metal parts (no egc)
OR
Run a ground wire back to panel that feeds this panel. (ground rod not required by this art.)

First choice is correct for 3 Wire feeders, not for new work. It's the old school method.

Second choice is correct, 4Wire feeders required for new work. Grounding electrode may not be required in CEC but it is in the 2011NEC.

Here's another article saying the same thing in different words.
http://www.mikeholt.com/technical.php?id=grounding/unformatted/separatebuilding&type=u&title=Separate%20Buildings%20and%20Structures%20%284-26-2K%29

NEC 2011 250.32

250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s).

(A) Grounding Electrode. Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250. The grounding electrode conductor(s) shall be connected in accordance with 250.32(B) or (C). Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.

Exception: A grounding electrode shall not be required where only a single branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor
for grounding the normally non–current-carrying metal parts of equipment.

(B) Grounded Systems.
(1) Supplied by a Feeder or Branch Circuit. An equipment grounding conductor, as described in 250.118, shall be run with the supply conductors and be connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor (neutral) shall not be connected to the equipment grounding conductor or to the grounding electrode(s).

Exception: For installations made in compliance with previous editions of this Code that permitted such connection, the grounded conductor run with the supply to the building or structure shall be permitted to serve as the ground-fault return path if all of the following requirements continue to
be met:
(1) An equipment grounding conductor is not run with the supply to the building or structure.
(2) There are no continuous metallic paths bonded to the grounding system in each building or structure involved.
(3) Ground-fault protection of equipment has not been installed on the supply side of the feeder(s).

If the grounded conductor is used for grounding in accordance with the provision of this exception, the size of the grounded conductor shall not be smaller than the larger of either of the following:
(1) That required by 220.61
(2) That required by 250.122

 

[sberry]

I didn't read it word for word but the canuk said they used a water pipe, pretty much the same as a rod. I got to agree with MTW, the suppression doesn't work without the ground and as I mentioned earlier I fixed the grounding on my incoming phones and no more power strip blow outs. Don't even unplug anymore during storms. It used to be a routine event.