13 posts / 0 new
Last post
Dmurr33
Whole House Surge protector

Hi,

I'm looking to install a whole house surge protector in my 150 amp panel. I remember an electrician telling me that the panel is at max capacity despite there being a few open slots.

Slots 2 and 4 (hopefully "slots" is the right term for it) are currently open, which I believe would be the right location to install the whole house surge protector. My question is, can I even add the surge protector if the panel is already maxed out? I have no idea how this all works.

Any advice will be greatly appreciated!

Thanks!

Dave

canuk
Re: Whole House Surge protector

The surge protectors don't draw any load ( very very little only to power up the LED status lights ) . The only thing adding the surge protection would contribute is filling the two remaining slots ( or spaces ) -- perhaps this what you mean by maxed out ?

JLMCDANIEL
Re: Whole House Surge protector

I have no idea what he means by max capacity unless he did a load test. Unless your house is extremely large and/or you have electric heat, I doubt you would ever come close to using a full 150 amps. As Canuk says the surge suppressor uses little power so should not add to load.

Jack

Re: Whole House Surge protector

Dmurr, you can buy surge protectors that: mount inside the service entrance panel on a stab, lay inside with wires run to an existing two pole breaker & the neutral, outside the panel through a knock-out (run wires to a 2 pole breaker and the neutral bus, per directions.

Keep the wires as short and straight as possible (3" to 4" is good), or the lightning will jump off the wire and you will loose your protection.

It's a good investment that can save a bundle. You may never know what didn't burn your house down, unless the protector melts during a storm.

Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com

Dmurr33
Re: Whole House Surge protector

Guys,

Thanks a lot for the advice. I really appreciate it. I have a 2,000 sq. foot house that runs on oil heat (punishment for living in Rhode Island), so I'm definitely not using a ton of electricity.

And I'm not sure what my electrician meant either, but I thought I'd pass it along.

Thanks again!

Dave

Sombreuil_mongrel
Re: Whole House Surge protector

Do these "whole House" surge protectors prevent damage from surges within the house (like from a loose neutral in a j-box) or just on the incoming service? Both?
Casey

canuk
Re: Whole House Surge protector

The protectors mounted in the panel only handle incoming surges on the service lines. Surges created within the home are handled by point of use protectors --- the kind you plug in --- which should also be used even though you may have a whole house protector.

Re: Whole House Surge protector

Most surge suppressors have at least three Metal Oxide Varistors (MOV) rated 130V for use on a 120V circuit. They're about 3/16" thick and 1 1/4" in diameter. They have two leads and connect: one line to line (across black and white). Another goes from hot to ground and the third goes from neutral to ground.

For more protection five or more may be tied across each point mentioned above. Years ago when they first came out I ordered one to protect an entire industrial facility (which it did). The box was riveted together and a warning label stated if the box was opened it voided the warranty (which I did). The 480V/277V device contained hundreds of MOV's.

Whole house units use a 260V MOV across the two hots, usually just tied across a 240V 2 polebreaker. The hot-ground and neutral are 130V.

They can stand very high peak voltage spikes lasting fractions of a second long. In the case of an open neutral where 200V or more may be felt across a TV for long periods of time both the TV and the 130V MOV are usually fried to a crisp.

Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemiretiredelectrician.com

Fencepost
Re: Whole House Surge protector

All MOV surge supressors have a "joule rating." A power surge is also measured in joules. MOVs get used up. So if you have a 5,000 joule MOV, and you get a 20 joule surge, the MOV is now good for 4,980 joules. (That's a BIG surge suppressor. Most are rated 500-1500 joules, and that rating is the sum of all the MOVs in the supressor. So if you've got a 1200 joule supressor, that's probably 400 joules hot-neutral, 400 joules hot-ground, and 400 joule neutral-ground. The 400 joule neutral-ground is unlikely to ever come into play, so your effective rating is more like 800 joules.)

As you can see, eventually it will wear out and will no longer be able to protect your appliances. That's why it's a good idea to replace the surge protectors for your electronics every several years (more often if you have dirty power or a lot of electrical storms).

Some have LEDs that indicate protection is working. They do not tell you when it is *almost* used up. So if there's only 100 joules left and you get a 200 joule surge your appliances and electronics are toast. (That's a BIG surge you'd only see in a direct lightning strike or a primary utility line contacting your residential feeder.)

That said, there are SOME surge protectors that will interrupt the circuit when they fail. I'm not aware of any whole-house protectors that provide this kind of protection.

Re: Whole House Surge protector

Good advice Fencepost and would like your opinion:

I read somewhere that typical housewiring will tend to limit spikes to about 600V due to clearances in devices etc.

Also, I feel secondary surge strips located around a house will add further protection to not only the appliances plugged into them but the whole house. By their very nature their MOV's are connected L-L, L-N & L-G so wouldn't "more be better"?

Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com

Fencepost
Re: Whole House Surge protector
The Semi-Retired Electric wrote:

Good advice Fencepost and would like your opinion:

I read somewhere that typical housewiring will tend to limit spikes to about 600V due to clearances in devices etc.

Also, I feel secondary surge strips located around a house will add further protection to not only the appliances plugged into them but the whole house. By their very nature their MOV's are connected L-L, L-N & L-G so wouldn't "more be better"?

Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com

I wonder if that "600V" figure is based on the fact that the insulation on most household wiring is rated for 600V. It seems a bit fishy; there could be effectively a spark gap between the internal prongs of a receptacle, say, but there are so many variables and variations that there's no way you can count on some 600V rule of thumb.

I am of the "more is better" opinion, but still the MOVs should be located near the protected device as voltage transients can be very localalized. For example, a laser printer can draw several amps when it is printing. When it stops printing, the current draw suddenly stops, and a surge can happen on that circuit. If your computer is on the same circuit, it can experience a small surge. Having the laser printer and the computer on a surge protector can protect both. (By the way, laser printers should NEVER be connected to a UPS. It will overload the UPS.)

When you start talking about stuff that happens in radio frequency ranges, weird things happen. For example, if you get some funky, high-voltage standing wave in the wiring and the MOV happens to be at a node and the device is at an antinode, the device blows up and the MOV doesn't know anything happened.

Pages

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.