Whole house surge protector wiring question

[trader4]

I'm helping a friend of mine who wants to install a Panamax GPP8005 whole house surge protector, which gets mounted next to the main panel. The instruction say it can be connected to the main panel using either a double 30 amp breaker or preferably using a sub-feed lug kit.

The picture of the unit shows it with wires coming out, ready to be attached. So, I understand the connection method using the breakers. But, if we followed the directions and connected it using a sub-feed lug kit, wouldn't that be a major code violation? The only protection then would be the main panel 150 amp breaker, which would be incompatible with whatever gauge wires are coming out of the surge protector, because if they can connect to a 30 amp breaker, they surely can't handle 150 amps. So, am I missing something here?

Here's the install instructions and pics if you want to look:

[Ralph Mowery]

I did not see what size wires were being used , but if they are # 10 or larger (one refferance did seem to give the impression of # 6) They should be large enough. They only have to be able to carry the current long enough to blow the main breaker. That should only take a a second or so, not hours as if the thing was actually using any power so to speak of.

[trader4]

No other opinions on this? I was hoping someone could spell out how the code allows this?

[Ralph Mowery]

Look about half way down :

[trader4]

Thanks for pointing me in the right direction. The Siemens article talks about NEC 280 that covers this stuff. Some googling on that produced more good stuff.

[bud--]

The Siemens article also includes TVSSs (transient voltage surge suppressors) which were covered by NEC article 285. That is what you have. They must be connected downstream from over current protection (article 280 "surge arresters" can be connected ahead of the service disconnect).

NEC articles 280 and 285 were reorganized in 2008. In one of the changes TVSSs are now called SPDs (surge-protective devices) - still under article 285.

SPDs are covered by UL1449. Since the "second edition", which was effective in 1998, SPDs (both plug-in and service panel) have been required to have protection built in to disconnect failing MOVs. It commonly responds to overheating MOVs and may also include fuses. The internal protection will protect the wires.

Minimize the wire length and avoid sharp bends. The clamp voltage is higher the longer the wires are because of voltage drop through the wire impedance, which is significant for surges. If wires are fairly long lightly twisting them is a good idea. The rated clamp voltage is for 6" lead length for SPDs made now. The IEEE guide at

talks about lead length starting document page 22.