I have a whole house SPD to install, and am not able to move the existing breakers down in order to install the dedicated breakers near the top corner of the panel. My two options are:

1. Install the two 20A breakers at the bottom of the panel. Does it really make a huge difference that they be near the bottom in lieu of near the entrance?

2. Double tap a 20A 2 pole breaker already existing near the top of the panel.

Thanks.

I am leaning towards option 1.

 

I like to see surge protectors connected at the top (or more exactly, closest to the main breaker). In theory, this best limits the surge seen by other circuits. In practice, I doubt it makes much difference.

Having said that, why not just install a new double 20 at the bottom and extend the circuit now going to the top double 20 to use the new breaker. Then use the top double 20 for the SPD. All you need is a couple of feet of wire and a couple wire nuts to extend the existing circuit....

If the breakers are marked as suitable for two wires, then I believe double tapping is allowed; I still avoid it.

 

That was another option, but then I read that you should try and avoid wire nuts in a panel as well.

I will probably just end up running the SPD at the bottom. Anything is better than nothing right...

I hear so many mixed opinions on whether or not it really needs to be at the top or not.

 

Like I said, I doubt it makes that much difference. Having it connected at the bottom is certainly better than not having it at all.

Wire nuts in the panel are perfectly fine and it's done all the time, especially when doing a panel upgrade or adding circuits.

 

Consult the manufacturer's installation instructions. Many manufactures say it makes no difference where in the panel the device is connected.

 

Some manufacturers specify installing the spd in the top corner. My feeling: this merely a frivolous warranty caveat.....if you don't install spd as they indicated, they conveniently void their warranty. The reality, I believe, is that installing the spd in a specified location so it functions properly or better is technically indefensible.

 

I agree with Gen. To think the voltage drop across the length of the bus bars is greater than the voltage drop across the 20 ampere CB and the #12 conductors to the surge suppressor is simply ludicrous.

 

The instructions do recommend installing it near the top, but I agree that it is likely a warranty caveat as well.

Like I said, I am going for the bottom left corner and calling it a day.

Anything is better than nothing right.

 

All this is about impedance. Every foot longer increases impedance. That protector is not doing protection. That protector must connect low impedance to what does protection.

Follow a bar copper, quarter inch wire from breaker box to earth ground. How long is it? If that wire goes over the foundation and own to earth, then impedance is excessive. Wire is too long. Wire has sharp bends over the foundation.

Protection is defined by lower impedance. If a connection from incoming AC mains to earth is shorter, then protection increases. So yes, better is to connect it closer to an incoming surge. That also reduces connection length. But better is to refocus attention on what really increases protection. A shorter connection to single point earth ground. And upgrading what is the protection - earth ground.

 

Interesting. What you say makes sense. However then I would wonder how much the added small impedance compares to the magnitude of a massive surge. How much would the impedance of say 1 extra foot of #12 in a panel reduce the surge protection? While your point is valid would it be really enough to consider the SP location?

 

A surge is a current source. That means current will flow no mater what would restrict it. An impedance increase means an increased surge voltage. Even sharp wire bends increase impedance.

How much does shortening wire by 12 inches accomplish? Locate a protector so that its wire is short to both incoming AC and to that earth ground hardwire. Other factors such as convenience, safety, and ability to make future changes are relevant. If the protectors wire is 18" and if it only needs 6" to connect. Then I would make that wire more like 10" or 12" as long as it has no sharp bends.

More important may be changing a ground wire routing - as summarized above. It should be shorter, as described. Must not have sharp bends, no splices, be separated from other non-grounding wires, and not be inside metallic conduit. IOW rather than worrying about how that wire connects inside a box, worry more about how that earth ground wire routes AND the quality of single point earth ground.

BTW, if any other wire enters without a low impedance connection to the same earth ground, then above recommendations are compromised. For example, TV cable must also make that low impedance connection to earth - without any protector. Telephone already has a protector installed for free. That also must connect low impedance to the same earthing electrode.

In short, worry less about protector placement since more often greater improvement is found in a other parts of a connection to earth.

BTW a 'whole house' protector should be at least 50,000 amps.

 

Optimally, you want to clamp close to GROUND. The bus bar length to L1, L2 is not a factor; actually you want a long bus (higher inductance) upstream.
Also, this top vs down is nonsense. The line could come in the bottom or top...

 

So I installed it in he first two available slots near the bottom of the panel (away from the entrance) as that was the only viable option without practically completely redoing the panel. By locating it there, I was able to cut the leads to the SPD down to about 5 or 6".

Something is better than nothing I suppose.


Now, once the ground thaws I need to install proper grounding to the panel. For some reason, there is currently only one ground going to the copper water supply pipe, however there is a water filter housing (plastic upstream) so that isn't doing much of anything for me, and the water supply coming in through the foundation from the well is plastic as well.... I need to have digsafe come map out the underground entrance so I know where I can safely pound in the rods. I am going to go with 2 8' rods, 8' apart along the side of the foundation with a continuous piece #6 copper cable.

 

So you basically don't have any ground? Not good!

Don't know how old the house is, but you will get a better ground if you keep a little away from the house so the rods aren't sunk into backfill (and so they don't puncture your foundation drains!). I try to put the first rod at least 3 feet away from the foundation and the other about 10 or so.

If the well casing is anywhere nearby, it makes a good extra ground connection point, assuming it's steel.

 

The house is from 2006, so I honestly don't know how they got away with it...

The panel has the 3 service feeds (2 hots and the one connected to the neutral bar), however, there is only the one ground wire going to the water pipe from the other ground/neutral bar.

Is there any other way they could have done it? Am I missing something obvious here?

EDIT, looking back, I think it is grounded via the neutral from the service entrance. The ground and neutral bars are tied together.

 

You need 3 ground points per code. One to the water, which you have and the other 2 from the panel (in one continuous run, no wire breaks) to 2 ground rods outside, which I believe should min. 6 ft apart, using #4 wire. You need the latter 2. Better ground = better surge protection. Your Maine code may or may not allow aluminum rods...others may clarify.

 

NEC allows #6 cu to ground rods. Different requirements if connection to water pipes or UFER. Some jurisdictions modify this requirement, so it's best to double check with AHJ.

 

Close, but not quite correct. The NEC only requires one ground rod as long as resistance to ground is 25 ohms or less. In lieu of proving the resistance, the NEC allows you to install a second rod at least 6 feet from the first rod. The conductor to the ground rod never needs to be larger than a #6 and must be continuous to the first rod.

I have never heard of an aluminum ground rod. The most commonly recognized ground rod is copper clad steel (1/2" X 8' minimum), but I have also seen stainless steel ground rods.

 

Thanks guys....And North Maine just FYI in case you don't know....check with AHJ...means authority having jurisdiction....as in your local electric code official, which maybe, depending what North part of Maine you're in, doesn't even exist.

 

Thanks for all the replies guys. Is the 3 ground point relatively new or? What was the requirement in 2006?

I can't imagine they got through all the inspections with an "ungrounded" panel...

Like I asked, is there any other way they could have done it that might not be so obvious?

 

The most common ways (that I'm familiar with at least) are ground rod or rods, bonding to metallic water pipe that runs outside underground, or attachment to the rebar in the foundation.

Any/all of these are usually bonded with a heavy gauge (#6 or #4) bare copper wire that is supposed to be bonded to the neutral in the main panel.

But there are complicating variations. Some POCO's require the bond to be at the meter base. If you have an external main breaker ahead of your main circuit breaker panel, the ground should be bonded to neutral there instead.

Metallic water pipes will be bonded to ground for safety even if they are not used for the grounding electrode because, for example, the pipe feeding the residence is plastic.

You will also often see any metal beams used for structural support bonded for safety reasons.

So look for heavy copper wires coming out of your main panel, the meter base, and any external breaker box or disconnect.

 

I will have to take another look at the meter. I do have an external meter which is feeding the main panel (only panel).

Like I said, there is very obviously the neutral from the supply which is bonded to the neutral/ground bars, that is on the right hand side of the panel (facing it), then on the left hand side, there is only the one ground wire which makes its way over to the water pipe.

I will take a look at the meter tonight.

 

Do you not have a ground wire from the well casing to your pump controller?

 

I will have to take a better look. I'm not sure.

 

One small but important detail.....you should have a #4 or #6 jumper across the water meter..... if you have one.

 

It's a well, not a meter.

 

You might have a CEE, AKA a Ufer ground. If so, no other electrodes like rods are required.

This differs from the NEC. Also the GEC only needs to be continuous to the first rod. Between rods is a bonding jumper.

You will not find AL ground rods. They will be galvanized or copper clad rods. Also an AL GEC cannot connect within 18" of earth.

 

I don't believe I have a Ufer ground.

I didn't get a chance to look last night. I will try to do it this weekend.

 

Here is what I have going on.









So I moved the water pipe ground to below the filter so it is technically bonded to the well casing via the pump controller.

Without digging under the meter though, not sure how I could verify ground rods. The building inspection states ground rod grounding...

 

In seeing what is going on outside the house by the meter, the only way it could be grounded with rods is if they came from the meter through the conduit, and exited the conduit below ground level.

The last thing I can do which would remove all doubt is have the POCO come cut the seal and open the front of the meter panel.

 

So there is a ground wire in the meter housing that runs down the conduit the feed from the pole comes.

Is there any reason why they would have run the ground all the way back to the pole about 150yds away to tie into the ground for the pole?

 

The connection in the well casing looks suspect . The egc is not large enough to act as the gec to the well casing.

 

What do you recommend as a replacement?