What is this?

[Jim Hughes]

Hey Gang:
I saw this on an electrical panel located in the basement next to the well pump. This "transformer"? has stranded aluminum wires that is double tapped at the 220 v breaker for the well pump. What is this and what does it do?
And how should it be properly wired in to the panel?
Thanks,
Jim

[Michael Thomas]

Looks like a "surge suppressor", but I don't recognize the brand. If it is a TVSS the manufacturer's instructions will control whether it can be connected to an existing breaker, BUT the breaker has to be listed from multiple connections of the wire types and size used. Also, the instructions may require twisting the leads (usually, at least 1/2 turn per 12").

[John Ghent]

It looks like a lightning supressor.

[Rob Thomas]

It's a lightning arrestor. It can be double-tapped on that Square D breaker as long as the conductors are the same size.

Oddly, the instructions with many arrestors recommend placing them INSIDE the enclosure and connecting the conductors to any breaker (regardless of the terminal design). This helps sell arrestors but it doesn't necessarily meet the requirements of the NEC.

I have seen instructions for one brand of arrestor that specify connection to a dedicated breaker.

The installation in your photos is as good as any I have seen.

RT




Hey Gang:
I saw this on an electrical panel located in the basement next to the well pump. This "transformer"? has stranded aluminum wires that is double tapped at the 220 v breaker for the well pump. What is this and what does it do?
And how should it be properly wired in to the panel?
Thanks,
Jim

[Jerry Peck]

However, the white is connected to a breaker instead to the neutral terminal bar, which means, I guess, that the black is connected to the neutral terminal bar - meaning ... it is wired backward.

Plus, they are required to be installed mounted outside the enclosure, like that one is.

They are also one time hit units - has that been hit already, does it offer any protection now? I'm not going to say it's any good.

[Thom Walker]

When wired properly, what all is it designed to protect?

Is there some kind of visual indicator for when they're good and when they've taken a hit? I've never seen one. Thanks for the post.

[Jon Randolph]

Isn't it wrong to double tap a 220v circuit, regardless of the breaker style?

[Jim Luttrall]

Thom, I put one in at my house. GE panel and surge protector that installs just like a breaker. It has a green light that is visible as long as it is working. I put it in a year ago and so far so good (although that reminds me I need to go look at it). It is designed to protect the whole house.
I bought mine at a big box store for less than $50.
Jim

[Jerry Peck]

Isn't it wrong to double tap a 220v circuit, regardless of the breaker style?

Not if the breaker terminals allow it.

[Jerry Peck]

When wired properly, what all is it designed to protect?

IT is designed to take a major surge or voltage spike / lightning strike to ground. To protect everything downstream of it.


Is there some kind of visual indicator for when they're good and when they've taken a hit? I've never seen one. Thanks for the post.

On those types, no, unless they suffer a severe hit (like lightning), in which case many of them swell up, or even explode open ('explode' may be too strong of a word - 'pop' open).

If they are swollen, they've taken their hit, if they are not swollen, you just don't know, could be yes, could be no.

[Rob Thomas]

It looks to me like that white wire is the second ungrounded conductor on the circuit that is connected to that 240-volt breaker, which leads me to believe the arrestor is wired properly.

RT


However, the white is connected to a breaker instead to the neutral terminal bar, which means, I guess, that the black is connected to the neutral terminal bar - meaning ... it is wired backward.

Plus, they are required to be installed mounted outside the enclosure, like that one is.

They are also one time hit units - has that been hit already, does it offer any protection now? I'm not going to say it's any good.

[Nick Ostrowski]

Based upon the premise that these whole house supressors are supposed to protect all the circuits in the house, why are some installed further down in the panel and not on the main lugs? Seems to me that a downstream installation is only protecting part of the electrical system.

[Jim Hughes]

Thanks for all your help!

[Jerry Peck]

It looks to me like that white wire is the second ungrounded conductor on the circuit that is connected to that 240-volt breaker, which leads me to believe the arrestor is wired properly.

Except that when they use white wires they intend it to go to ground. They will use two blacks for the two to go to the ungrounded conductors (bus bars) and one white to go to the neutral terminal bar.

[Jerry Peck]

Based upon the premise that these whole house supressors are supposed to protect all the circuits in the house, why are some installed further down in the panel and not on the main lugs? Seems to me that a downstream installation is only protecting part of the electrical system.

Because you are not allowed to multiple tap the main lugs.

Tapping off a breaker off the bus bar protects the bus bar, which in turn protects every thing downstream. But it should not share a breaker, it should have its own, and, in fact, should just use a molded case switch as you don't want the breaker it is attached to to trip off. That would remove the protection it is providing.

[Rob Thomas]

I can't follow what you are saying. The two black wires from the arrestor are connected to the breaker. The white wire is part of the well-pump circuit on that breaker.

I outlined in red and yellow the two wires that I think originate from the arrestor.

RT


Except that when they use white wires they intend it to go to ground. They will use two blacks for the two to go to the ungrounded conductors (bus bars) and one white to go to the neutral terminal bar.

[Jerry Peck]

I outlined in red and yellow the two wires that I think originate from the arrestor.

I was looking at the other two wires as coming from the surge protector, the 'white one' and 'the other black one'.

Sorry about that.