Surge Arrestor Installation

The panel I inspected yesterday was a 150 amp split-bus configuration. The panel had numerous deficiencies (more than six disconnects, double taps, double neutrals, etc.), but it also had a surge arrestor installed.

This surge arrestor was installed on the 40 amp disconnect for the electric range. Plus, it was connected directly to the terminals (double tap).

So, my question is this:

Why would the surge arrestor be installed on just the 40 amp breaker to the range? Wouldn’t it be better for the arrestor to be installed on the main lighting disconnect breaker?

Since this is a split bus panel, installing the arrestor on the just the 40 amp range disconnect would not provide protection for the rest of the panel, would it? I always thought that if you install a surge arrestor on a single bus panel that the entire panel is protected no matter where you install it on the bus, but what about a split bus panel?

Any help would be appreciated :slight_smile:




Their is a difference between a Surge Arrestor and a TVSS in the allowance of their installation. A true lighting surge arrestor should be installed on the line side of the system without overcurrent protection ahead of it and the TVSS ( now called SPD’s ) should be on the load side protected by a overcurrent protection device. This appears to be a Lighting Arrestor installed on the load side of a breaker…The silver wrapping around the LA will/should say how it is to be installed based on the manufacturers intent…However…regardless of that I feel it will be pointless based on the installation…the conductors are not as short as possible and I (my opinion ) feel it will choke itself out and provide very limited protection.

To answer your question, no it should not connect to the range overcurrent protection device and chances are the OCPD is not rated for multiple conductors anyway…so defer to an licensed electrical contractor regarding all the other issues, ask them to verify if it is a lighting arrestor or a surge protector and install it in accordance with its listings ( not just laying in the panelbox…it is designed for a KO…then wash your hands of it…


Thank you very much for for providing your input. Your answer helps a great deal.

If this device were a true SPD, where in the panel would it be installed, if not on the 40 amp breaker for the range?

I understand that the device itself should not be laying loose in the panel and that the wires are too long (just learned that from you), but wouldn’t it provide surge protection to the top breakers on the split bus? And therefore, also provide protection of the 15/20 amp breakers on the bottom of the bus?

Just trying to wrap my head around the logic. I come across a lot of these devices that are double tapped on load side breakers. Most Electricians in my area say that it’s OK. This was the first time I encountered the device on a split bus, and it made me think a bit :slight_smile:


It would if it is a surge protector…if it is a lighting arrestor it should be on the line side of all those breakers and keeping the leads a short as possible. No, I see no reason to install it on a 40A breaker and in most all cases with a SPD it will not exceed a 15A or 20A breaker depending on the manufacturer.

Type 1: Permanently connected SPDs intended for installation
between the secondary of the service transformer
and the line side of the service disconnect overcurrent

Type 2: Permanently connected SPDs intended for installation
on the load side of the service disconnect overcurrent
device, including SPDs located at the branch panel.

Type 3: Point of utilization SPDs.

Type 4: Component SPDs, including discrete components,
as well as assemblies.