Murray fuse panel

Specific Inspection Topics Electrical Inspections
1

I ran into this on my last “mock” inspection.(yes I’m a newbe" :shock:)

Murray fuse panel. House was built in early 60’s.

  • Meter is 200 AMP
  • 4/0 Alum SEC (200 AMP)
  • 200 AMP rated panel

This is fine and would have said “200 AMP service” The question is the “Plugin Fusible Components” are - 100 AMP (top) and 60 AMP (middle).

There is a 100 AMP “sub-panel” located in another area and there is an add-on breaker for the A/C mounted on top of the main service panel.

All fuses are either 15 or 20 AMP.

My questions – Is this really a 200 AMP service? And should this be updated to a new breaker panel?

Top.JPG
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Panel.JPG
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2

Wow What a beauty. Never seen one like this. For you to run into this on your first few mock inspections is a great learning experience.

My thoughts: (Im sure Paul Abernathy will spank me with his vastly superior knowledge)
You go by the lowest rated point, if it is a 200 A panel, but 100 A feed wire, it is 100 A. If there are 2 100 A main fuses (one per lag) I would call this a 200 A panel.

As for replacing, I would recommend updating based on age and useful life. If it was put in in the early 60’s, it is 50 years old. My issue with Fuse panels is the Human element: I always find 20-30 amp fuses where a 15 amp belongs, circumventing the safety measures.

Post script Please put your location in your profile, thanks.

3

This would still be a 100 amp rated service. You do not add the ratings of the legs together.

4

Jim is correct. ( I looked it up) You cannot add the lags together, therefore it is only a 100 A panel.

5

But if the meter, service wires and main panel are rated for 200 amps, is not the “service” rated at 200 amps?

www.MauiHomeInspections.com

6

It’s better described as service capacity, rather than service rating. The service capacity is 100 amps.

If all components are rated for 200 amps except for one, the capacity is limited by that one component. So there’s no real point in reporting component ratings.

7

While the service entrance conductors may be 200 amp rated, the smallest part of the service is only rated for 100 amps.

8

Jim,
How do we know that from the information that Donald provided? He said that he has a 100 amp and a 60 amp plug-in fuse component. Do we know that the 100 amp is feeding the 60 amp? To me it sounds like he has a 100 amp and a 60 amp.

9

Is this panel a split bus panel?

It apears to me that it is. To me it would be rated at 200 amps which is the capacity of the panel, feeders and meter housing.

If you have a split bus pane & feeders that is rated for 125 amps and it has two 50 amp and one 30 amp breakers (within the 6 handle rule) you wouldn’t say it is a 30 amp. It would still be a 125 amp.

Just my opinion.

10

Here are some additional pics of the interior of the panel. It does appear that the top is feeding the bottom.

I hope these will explain this in a little more detail.

Panel Mid 1.JPG
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Panel Mid 2.JPG
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Panel Top.JPG
Panel Top.JPG800×600 89.4 KB

Panel Bottom.JPG
Panel Bottom.JPG800×600 68.8 KB

11

From the additional photo’s it looks to me like the panel has no main and 6 pull out overcurrent protection devices. Five on the top for various loads and the sixth one feeding the fuse portion on the bottom.

12

Very interesting older panel. Lucky to encounter one like that on one of your first inspections (even if it didn’t seem like it at the time). This is worth like 20 plain old mundane service panels as far as what you can learn from it.:mrgreen:

Michael - You’re under arrest for breaking Watts Law

Just teasing :wink: