Does My Tenant's Sub-panel Need a Surge Protector?

[lbohen]

Our farm has a main 200 amp panel in the barn which services the barn, an addition to the barn with an apartment, an herb-gardening facility, and our house. The 200 amp panel has a whole house surge protector on it.

My herb-gardening tenant installed a sub-panel from the 200 amp panel, so she now pays for the electricity going to the herb-gardening facility. The herb-gardening facility includes a metal framed hoop-house with a propane furnace, fans, a few outlets, and a separate structure that blow-dries herbs.

I believe the surge protector on the 200 amp panel will trip if the system is struck by lightning or an electrical surge and that the surge protector, once tripped, would have to be replaced.

If the herb-gardening facility got struck by lightning, should its sub-panel have its own surge protector to protect the 200 amp panel from being shut down?

 

[SparkySam]

Lightning strikes are so few and far between that the IET have removed that section from the regulations.
Technically if there is more than £80 of value plugged in to the sub board then there should be an SPD, how ever common sense would dictate that should there be a surge from the grid, it'll hit the incoming first. Personally I wouldn't worry about it as you have one at your source.

 

[nicebutdim]

OP is in Vermont, where different regulations will need to be taken into account.

 

[lbohen]

Lightning strikes are so few and far between that the IET have removed that section from the regulations.
Technically if there is more than £80 of value plugged in to the sub board then there should be an SPD, how ever common sense would dictate that should there be a surge from the grid, it'll hit the incoming first. Personally I wouldn't worry about it as you have one at your source.

I was thinking that if lightning hit my tenant's herb-gardening facility the surge would travel to her sub-panel and then to my 200 amp panel. Is this correct?

 

[SparkySam]

Sorry OP, I was talking UK regulations. I don't know enough about where you are to make an educated comment, but
Technically yes, the surge could travel back up towards the house. Spd's only protect against transient voltage. They wouldn't take a direct hit. If you're that concerned, you need to look into lightning protection, which is different from spd protection.

 

[James]

Spd are likely to help if you get a nearby lightning strike to the ground or to the grid some considerable distance away.

however, they will not help if you have a direct strike to any electrical part of your property, this includes any metalwork that is connected to the earthing or even close to the earthing conductors in the property.

remember that lightning has already traveled 10’s of thousands of feet to get as far as your property, a surge protector or even a couple of feet between a conductive material that lightning strikes and any other cable that is part of the electrical installation is not going to make a difference.

 

[lbohen]

Sorry OP, I was talking UK regulations. I don't know enough about where you are to make an educated comment, but
Technically yes, the surge could travel back up towards the house. Spd's only protect against transient voltage. They wouldn't take a direct hit. If you're that concerned, you need to look into lightning protection, which is different from spd protection.

My primary goal is to prevent the farm's 200 amp panel from a lightning strike at the herb-gardening facility. My thinking is that if the herb-gardening facility has an SPD on it's 100 amp sub-panel, the farm's 200 amp panel would be protected. Is this correct thinking?

 

[davesparks]

My primary goal is to prevent the farm's 200 amp panel from a lightning strike at the herb-gardening facility. My thinking is that if the herb-gardening facility has an SPD on it's 100 amp sub-panel, the farm's 200 amp panel would be protected. Is this correct thinking?

If you want protection from a lightning strike then you need a lightning protection solution rather than surge protection.

An SPD protects against voltage surges, which may be caused be lightning strikes elsewhere on the power network, it doesn't protect against direct lightning strikes to an installation.

 

[Megawatt]

Our farm has a main 200 amp panel in the barn which services the barn, an addition to the barn with an apartment, an herb-gardening facility, and our house. The 200 amp panel has a whole house surge protector on it.

My herb-gardening tenant installed a sub-panel from the 200 amp panel, so she now pays for the electricity going to the herb-gardening facility. The herb-gardening facility includes a metal framed hoop-house with a propane furnace, fans, a few outlets, and a separate structure that blow-dries herbs.

I believe the surge protector on the 200 amp panel will trip if the system is struck by lightning or an electrical surge and that the surge protector, once tripped, would have to be replaced.

If the herb-gardening facility got struck by lightning, should its sub-panel have its own surge protector to protect the 200 amp panel from being shut down?

No because it is being fed from your main panel which has an SPD protection. If you was to have a surge in power everything coming from the main panel will be protected. Sorry for the delay in response and welcome to the forum.

 

[lbohen]

No because it is being fed from your main panel which has an SPD protection. If you was to have a surge in power everything coming from the main panel will be protected. Sorry for the delay in response and welcome to the forum.

My primary goal is to prevent the farm's 200 amp panel from a lightning strike or electrical surge coming FROM the herb-gardening facility. My thinking is that if the herb-gardening facility has an SPD on its 100 amp sub-panel, the farm's 200 amp panel would be protected. Is this correct thinking?

 

[Avo Mk8]

My primary goal is to prevent the farm's 200 amp panel from a lightning strike or electrical surge coming FROM the herb-gardening facility. My thinking is that if the herb-gardening facility has an SPD on its 100 amp sub-panel, the farm's 200 amp panel would be protected. Is this correct thinking?

Answers here have already discussed that an SPD is not a device to deal with local lightening Strikes.
I think adding an SPD to the herb garden facility panel will not achieve much, as there is already one on the incoming supply, as Megawatt advises.
To reduce the harm of a strike around the area of the herb facility, that facility really needs its own lightening protection.

Lightening protection is a different science from surges coming up the mains supply, and is dealt with by different regulations and different technical solutions. I'm not familiar with American regulations on this, and it does seem to be something of a specialist subject. I would suggest you check out lightening protection products, or maybe talk to a local company if there is one. This might be of interest:

Residential Lightning Protection | EMP Defense Advanced Lightning Suppression

Protecting your property from lightning strikes can help prevent damage to electrical systems, structure, roofing, electronic assets, as well as ensuring personal safety.

www.empdefense.us

NFPA 780: Standard for the Installation of Lightning Protection Systems

<p>1.1 Scope.<br />1.1.1 <br />This document shall cover traditional lightning protection system installation requirements for the following:<br /><br />(1) Ordinary structures<br />(2) Miscellaneous structures and special occupancies<br />(3) Heavy-duty stacks<br />(4) Structures containing...

www.nfpa.org

 

[Megawatt]

My primary goal is to prevent the farm's 200 amp panel from a lightning strike or electrical surge coming FROM the herb-gardening facility. My thinking is that if the herb-gardening facility has an SPD on its 100 amp sub-panel, the farm's 200 amp panel would be protected. Is this correct thinking?

You could install a SPD in the herb garden panel but it doesn’t protect against lightning. IT’s primary purpose is to protect surge’s from the power company which can happen when the power is out and suddenly comes back on.

 

[davesparks]

My primary goal is to prevent the farm's 200 amp panel from a lightning strike or electrical surge coming FROM the herb-gardening facility.

Surges won't be coming from the herb gardening facility. The power is coming from your main panel to the sub-panel and any surges will be going in the same direction.

As mentioned above surge protection does not protect against direct lightning strikes.