[curtisG]

I bought a whole house surge suppressor with the intent to install it in my main electrical panel.

http://www.smarthome.com/4839.HTML


After installing my HT sub-panel, I have no breaker space left in my main panel however (yes I know I could also install some of those half width breakers to make room).


But as an alternative, can this surge protector be installed in my HT sub-panel instead? That really is the gear I wanted to protect anyway.


--curtis

 

[greywolf]

The run from the sub panel to the equipment will probably be shorter than the run from the sub panel to ground. That would not be a good thing.

 

[Larry Fine]

While I don't disagree with Pat's reasoning, I'd say go ahead with the sub-panel installation. The voltage-clamping circuit pathway would be more direct, with less wire between the protector and the load.


Cascading protection is always a good idea, and the local location helps protect against in-house-induced surges. Can you afford two?

 

[greywolf]

I believe the choice for many people has been to use whole house protection at the main panel and the strip type at the equipment location.

 

[akshark]

Anyone making a whole house unit that uses Series Mode (SM) protection,it seems all I can find is MOV units.

 

[dwightrahl]

This may be a dumb question - if so, feel free to let me have it...


When you install a surge protection device in the main panel (or in a subpanel, for that matter), does it need its own dedicated breaker, or can it be tied into an existing 240v breaker? The few wiring diagrams/instruction sheets I've seen online aren't clear about this (to me, anyway).


Thanks,


Dwight

 

[curtisG]

Quote:

Originally posted by dwightrahl This may be a dumb question - if so, feel free to let me have it... When you install a surge protection device in the main panel (or in a subpanel, for that matter), does it need its own dedicated breaker, or can it be tied into an existing 240v breaker? The few wiring diagrams/instruction sheets I've seen online aren't clear about this (to me, anyway). Thanks, Dwight

It's a code requirement that the surge protection device be wired via breakers into the panel.

http://www.smarthome.com/images/4839dgm.jpg


--curtis

 

[curtisG]

Quote:

Originally posted by Larry Fine While I don't disagree with Pat's reasoning, I'd say go ahead with the sub-panel installation. The voltage-clamping circuit pathway would be more direct, with less wire between the protector and the load.

If I wire the surge protector into the sub-panel, should the green wire go to the ground bus (copper wires) or the neutral bus (white wires)?


In a subpanel, those two buses are separate, so am not totally clear on this issue.


Thanks


--curtis

 

[Larry Fine]

Curtis, to combine your two last questions:


You can add the protector to an existing breaker. Some breakers are approved for two wires (called "double-tapping" by some), and if not, just use pigtails and wire nuts. Use the lowest-rated two-pole breaker.


I'd connect the green wire to the neutral bus if the feeder's white wire is larger than its ground wire, for a lower-impedance return path. Otherwise, it doesn't matter.

 

[curtisG]

Quote:

Originally posted by Larry Fine Curtis, to combine your two last questions: .... I'd connect the green wire to the neutral bus if the feeder's white wire is larger than its ground wire, for a lower-impedance return path. Otherwise, it doesn't matter.

In a normal 10/3 cable, isn't the ground wire the same gauge as the other wires (white, black, and red wires)? A 40 ft run of 10/3 is what connects the HT subpanel to the main panel.


Thanks


--curtis

 

[curtisG]

OT question:


I bought the subpanel and 8 breakers from Home Depot a couple of weeks ago (4 x 15A and 4 x 20A). One of the 20A breakers doesn't work I found out today - it has a very high internal resistance (> 1Mohm), and is causing a high voltage drop.


My understanding is that electrical devices are non-returnable? If that's true, then this really stinks. I'm out > $10 for a DOA part..


--curtis

 

[akshark]

Larry,


I am building a new house and was wondering if you had any thoughts or recommendations on a whole house protection device. I have found several that employee MOV type of protection but none with SM type.

Thanks


Scott

 

[Fezmid]

Quote:

Originally posted by curtisG I bought a whole house surge suppressor with the intent to install it in my main electrical panel. http://www.smarthome.com/4839.HTML After installing my HT sub-panel, I have no breaker space left in my main panel however (yes I know I could also install some of those half width breakers to make room)

I just found out this past weekend that my breaker box is out of spots for new circuits and I still need to add 4 more circuits for the basement. I was under the impression that i'd have to hire an electrician to put a new breaker box in, but I saw you mention "half width breakers." Is there a way I can use some half-width breakers to avoid having to put a new panel in? or is that not their purpose (or even what they are?). Let me know -- I'd love to save some time and money.


CW

 

[curtisG]

Quote:

Originally posted by Fezmid I just found out this past weekend that my breaker box is out of spots for new circuits and I still need to add 4 more circuits for the basement. I was under the impression that i'd have to hire an electrician to put a new breaker box in, but I saw you mention "half width breakers." Is there a way I can use some half-width breakers to avoid having to put a new panel in? or is that not their purpose (or even what they are?). Let me know -- I'd love to save some time and money. CW

I think the correct terminology is tandem breaker

Here is a picture of what it looks like:

http://www.homedepot.com/cmc_upload/...s/355755_3.jpg


It's two breakers that fit in the space of one.


There are some rules about the total # of breakers that you can put in a sub-panel but still you should be able to free up some room in your main panel using these.


--curtis

 

[curtisG]

Quote:

Originally posted by curtisG In a normal 10/3 cable, isn't the ground wire the same gauge as the other wires (white, black, and red wires)? A 40 ft run of 10/3 is what connects my HT subpanel to the main panel.

Bump - was hoping to hear an answer on this before the weekend so that I can work on installing the surge protector.


Thanks!


--curtis

 

[DMF]

Quote:

Originally posted by curtisG I bought the subpanel and 8 breakers from Home Depot My understanding is that electrical devices are non-returnable? If that's true, then this really stinks. I'm out > $10 for a DOA part..

HD will take back just about anything. I returned a bad bell transformer last week. The original was bad (open primary) and the first replacement was bad (open primary). I didn't even know these things *could* go bad! It's just a chunk of iron with some wire wrapped around it! Grrr!

 

[Larry Fine]

Curtis, larger feeder cables, like #'s 8 & 6 also use a #10 ground. Yes, your #10 has #10 ground, and you can connect the surge unit's green to either; I suppose I'd select the ground, since it otherwise carries no normal current.


Also, you should have no trouble returning the bad breaker, as DMF said, since they don't normally go bad under normal use, and should simply trip if overloaded; sort of self-protecting. But, over $10 for a single-pole breaker?


Yes, they are called tandem breakers. Some, such as GE, are available in half-size bodies, like half of a tandem, and some are available in mixed sizes, such as 15/20, and some in "quad", like a 2-p 30 flanked by a pair of 20's, etc.


The rule for tandems reflects the 40-circuit-per-panel limit (42 for 3-phase). So, a 40-space panel will not accept any tandems, a 30-space will accept 10, etc., with 20 tandems in a 20-space panel being the maximum in a panel.


Any more than 40 circuits requires a sub-panel or second main panel. Typically, one would relocate two circuits (or one 2-pole circuit) to the new sub-panel, to make room for the sub-panel feeder breaker. Then add the new circuits.


On one job, a new kitchen was added, so I relocated four old circuits to the sub-panel, so the new range circuit could be powered from the main panel along with the sub-panel. This way, the sub-panel didn't require as much amperage.



Scott, I could be wrong, but I believe series-mode protectors are sized for branch circuits, and not for whole services. Generally, one or more series-mode protectors are cascaded with a whole-house protector for maximum protection.

 

[curtisG]

Quote:

Originally posted by Larry Fine Curtis, larger feeder cables, like #'s 8 & 6 also use a #10 ground. Yes, your #10 has #10 ground, and you can connect the surge unit's green to either; I suppose I'd select the ground, since it otherwise carries no normal current.

Larry - thanks again for all the advice.


One more question - the wire pig-tails on the surge protector are only about 6" long - not long enough to even reach the sub-panel from where I need to mount it.


What's the normal way to splice cables in a situation like this? I was planning on using flexible conduit for the run to the sub-panel. Do I need to install a junction box for this?


Thanks


--curtis

 

[emcgrath]

Look around at HD, I bought a surge protector there a few years ago that went in the space of two 20A breakers and served as the breakers too. For me this was the best of both worlds-really easy installation and didn't take any space out of my panel.

 

[Larry Fine]

Quote:

Originally posted by curtisG Larry - thanks again for all the advice. One more question - the wire pig-tails on the surge protector are only about 6" long - not long enough to even reach the sub-panel from where I need to mount it. What's the normal way to splice cables in a situation like this? I was planning on using flexible conduit for the run to the sub-panel. Do I need to install a junction box for this? Thanks --curtis

You're welcome.


Wire nuts, and some protectors need to be enclosed, and some don't. The one to which you linked has a threaded bushing, which fits a standard 1/2" KO (knockout - 7/8" actual). It's designed to be mounted directly to a panel.


You can indeed mount it to a junction box (or a box to it), make your joints there, and use a cable or conduit-housed wires to reach the panel. I'd use #12, and remember; the shorter the run, the better. Oh, by the way:

II. Installation

280.11 Location. Surge arresters shall be permitted to be located indoors or outdoors. Surge arresters shall be made inaccessible to unqualified persons, unless listed for installation in accessible locations.

280.12 Routing of Surge Arrester Connections. The conductor used to connect the surge arrester to line or bus and to ground shall not be any longer than necessary and shall avoid unnecessary bends.

III. Connecting Surge Arresters

280.21 Installed at Services of Less Than 1000 Volts. Line and ground connecting conductors shall not be smaller than 14 AWG copper or 12 AWG aluminum. The arrester grounding conductor shall be connected to one of the following:


(1) Grounded service conductor

(2) Grounding electrode conductor

(3) Grounding electrode for the service

(4) Equipment grounding terminal in the service equipment

280.22 Installed on the Load Side Services of Less Than 1000 Volts. Line and ground connecting conductors shall not be smaller than 14 AWG copper or 12 AWG aluminum. A surge arrester shall be permitted to be connected between any two conductors � ungrounded conductor(s), grounded conductor, grounding conductor. The grounded conductor and the grounding conductor shall be interconnected only by the normal operation of the surge arrester during a surge.