Whole home protection

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blue302

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I have a customer who has 120/240v 1200a service, single phase. They have a 1200 amp MDP at the service entrance with main breakers going out to 6-7 200 amp sub panels. Looking to protect the whole home. What would you suggest at the MDP combined with secondary protection at the panels. The homeowner is requesting something easy to use. Thanks.
 
Are we talking whole house surge protection, or are we talking back up generator???

I just saw the last part of your post, whole house surge at the MDP, then end of use at the loads needing protection, I have installed a few Leviton whole house surge units at mains a few times but to me they seem a little pricey?

Theres nothing really to use, as they just mount through a KO in the panel and have some pretty lights on them when powered.
 
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Multiple Surge Limiting

Multiple Surge Limiting

Surge voltages increase at changes in impedance, this means at the load. Surge protectors at panels will not see, and will dampen less, surges than surge protectors located at the loads. You can install surge protectors at panels but I encourage the homeowner to install surge protectors at outlets or plug strips serving critical loads.

Each surge protector can absorb a certain amount of energy before failing. The more total "joules" of capability, the better the protection.

I personally do not like surge protectors at panels because they are expensive, expensive to install, and expensive to replace. Spending as much on a slew of plug strips with high joule ratings has always seemed more prudent to me. But, the homeowner wants them at the panel, so be it.
 
beanland said:
Surge voltages increase at changes in impedance, this means at the load. Surge protectors at panels will not see, and will dampen less, surges than surge protectors located at the loads. You can install surge protectors at panels but I encourage the homeowner to install surge protectors at outlets or plug strips serving critical loads.

Each surge protector can absorb a certain amount of energy before failing. The more total "joules" of capability, the better the protection.

I personally do not like surge protectors at panels because they are expensive, expensive to install, and expensive to replace. Spending as much on a slew of plug strips with high joule ratings has always seemed more prudent to me. But, the homeowner wants them at the panel, so be it.
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How can the voltage be higher at the load than at the panel? The knock against panel protection is because the MOV's in a larger protector have a higher cut-over voltage and may not protect against smaller surges that a surge-strip would catch.

Also, surge protection at the panel protects things like dishwashers, ranges and fridges that are not normally on a surge strip. I have seen many appliances damaged by surges.

Mark
 
busman said:
How can the voltage be higher at the load than at the panel? The knock against panel protection is because the MOV's in a larger protector have a higher cut-over voltage and may not protect against smaller surges that a surge-strip would catch.

Also, surge protection at the panel protects things like dishwashers, ranges and fridges that are not normally on a surge strip. I have seen many appliances damaged by surges.

Mark
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A surge transient voltage spike is a high frequency event, and conductors that would be a low impedance path at 60 hz. can be several hundred thousand ohms, at these frequencies, this is also true for lightning, while I say having both is about the best you can expect to do, placing TVSS's at the load to be protected will many times do more to protect against in house generated transients from inductive loads.
The above HF issue is the main reason we are required to keep the leads as short as possible on whole house surge protectors, putting the surge protector at the load goes even father.
 
busman said:
How can the voltage be higher at the load than at the panel? The knock against panel protection is because the MOV's in a larger protector have a higher cut-over voltage and may not protect against smaller surges that a surge-strip would catch.

Also, surge protection at the panel protects things like dishwashers, ranges and fridges that are not normally on a surge strip. I have seen many appliances damaged by surges.

Mark
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Surges will burn houses down, too.

True scenario: Wind blew hard enough to slap a couple disty lines together. When they came away from each other, tranny surged. Surge turned a night light into a heating element. Light caught fire, which spread to a curtain, which started a fire that completely destroyed a 350,000 dollar real log home.

We got the EC work on the new home. Whole house protection was mandatory by the HO and strongly recommended by the insurance company and the POCO, who admitted that the fire was the fault of their equipment being affected by a storm. The unit we installed at the main was cheap, about 100 bucks.

At that time I boned up a bit on surge protection. I found that the surge strips can actually catch fire on their own if not protected upstream by a whole house protector at the main disco.

The 100 dollar one was for a 200 amp service. I have never priced one for a 1200, but if someone can afford a house big enough for a 1200 amp main, I don't think a surge protection device will bankrupt them.
 
beanland said:
Each surge protector can absorb a certain amount of energy before failing. The more total "joules" of capability, the better the protection.
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I would argue that clamping voltage and surge amp (kA) ratings are the most important, a lot more than Joule ratings. Manufacturers can beef up their Joule rating by testing a lesser surge over milliseconds. Most surges and lightning occur over micro-seconds, making their Joules claim pretty much useless.

K8MHZ said:
At that time I boned up a bit on surge protection. I found that the surge strips can actually catch fire on their own if not protected upstream by a whole house protector at the main disco.
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New SPD's manufacturerd under the new UL 1449 are required to have a series fuse to prevent this from happening.
 
wirenut1980 said:
New SPD's manufacturerd under the new UL 1449 are required to have a series fuse to prevent this from happening.
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Reading through 1449 was no fun and I didn't see anything about a series fuse. (That doesn't mean it wasn't there).

I did see this:

Type 3 - Point of utilization SPDs, installed at a minimum conductor length of 10 meters (30 feet) from the electrical service panel to the point of utilization, for example cord connected, direct plug-in, receptacle type and SPDs installed at the utilization equipment being protected. The distance (10 meters) is exclusive of conductors provided with or used to attach SPDs.
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That's the first I ever heard about any minimum conductor length.

I did see some discussion on a site that the newer SPD's have thermal limiters placed close to the MOV's which is supposed to prevent them from catching fire. Maybe they were referring to thermal fuses in series with the conductors.

I read through the White Book and the surge strip I have is UL listed as a 'Transient Voltage Surge Suppressor' which is coded as 'XHUT'. I see nothing there that specifies any thermal protection.

Next time I am out, I will look at brand new strips to see how they are listed.
 
Instead of outlet strips with surge protection built-in, why not use the receptacles with surge protection built-in? Much neater and you're assured of a reliable connection to the EGC with a hard-wired outlet. Also, outlet strips are actually listed as 'temporary power taps', but, the way most people use them is permanently and to replace the permanent wiring of the structure, which is a violation.
 
We install a lot of whole house surge protection. We normally use Cutler Hammer Ultra on 200A and under services. We use Delta for the bigger services.
 
K8MHZ said:
Reading through 1449 was no fun and I didn't see anything about a series fuse. (That doesn't mean it wasn't there).

I did see this:



That's the first I ever heard about any minimum conductor length.

I did see some discussion on a site that the newer SPD's have thermal limiters placed close to the MOV's which is supposed to prevent them from catching fire. Maybe they were referring to thermal fuses in series with the conductors.

I read through the White Book and the surge strip I have is UL listed as a 'Transient Voltage Surge Suppressor' which is coded as 'XHUT'. I see nothing there that specifies any thermal protection.

Next time I am out, I will look at brand new strips to see how they are listed.
Click to expand...

I do not have the actual standard. I was para-phrasing from a document for a class I attended. I did mis-speak a bit, it did talk about thermal fusing and not a series fuse, small difference there...

The actual language from the class talked about having the new standard ensure that the SPD have the ability to disconnect itself from the system for failures at various fault current levels. The device shall not exhibit evidence of a risk of fire or shock hazard.

I would imagine the requirement would be met by a thermal fuse in power strips and receptacle SPD's. If the SPD is connected to a panel, a breaker or fuse would meet the requirement.
 
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