Here's the written explanation I received from the property owner.
The fusebox in the picture is the way electrical installations were done up through the 50's into the early 60's. There is nothing wrong with this type installation and in some applications it is still being used today. The use of the fan is to maintain the current carrying capacity of the fuses. If the heat gets above perhaps 100 F then the current carrying capacity will be deminished by a certain amount and when the load approaches the max for the fuse it will blow at a lower than rated load. This will cause inconvenence for the tenants and lead to more replacing of the fuses.
There is no particular fire exposure with this type of electrical installation as most buildings that were constructed up to the 60's and have not converted to circuit breakers do not have any greater chance of fires started in these installations than you would have in the circuit breaker boxes but rather in the wiring on the user side which is where the vast majority of electrical fires start. When the fuse fails it will always fail in the shutdown mode in that electricity can no flow through it to the user side.
There is nothing wrong with this type installation........
Sure, when it is used in the manner the manufacturer intended. With the multiple violations/hazards I see in this picture, I hope this smarty-pants owner has his liability insurance paid up.
Let's start with leaving the door open, exposing the live buss and fuses;
Add the tap off the LINE bus with the white asbestos covered wire;
Add the attachment of the worklite to the can for a "neutral" (Bet the lite is used to find dead fuses);
Add the RED wire at the bottom which is at least another unfused tap or is more likely bypassing that bottom fuse!
The use of the fan is to maintain the current carrying capacity of the fuses.
One of the stupidest excuses I've heard in years. If things in that panel are getting so hot that the fuses are blowing from the heat, the whole panel is a fire waiting to happen! And what if the fan quits? Now you have an open panel to let the potential fire/arc from exploding fuses out in the open.
This will cause inconvenence for the tenants and lead to more replacing of the fuses.
Boo-de-freakin-hoo!!!! So the tenants lose power because they're overloading the circuit. It'll be a lot more inconvenient when the building burns down!
....do not have any greater chance of fires started in these installations than you would have in the circuit breaker boxes but rather in the wiring on the user side which is where the vast majority of electrical fires start.
There are exceptions to every rule and this situation fits that call.
When the fuse fails it will always fail in the shutdown mode in that electricity can no flow through it to the user side.
Unless it's bypassed by the piece of red THHN.
To Tommy O.: I sincerely hope you didn't touch any of the electrical system in that entire building. You may have left yourself open to some grave liability thanks to that owner's cavalier and incredibly foolish attitude toward electricity!!
I give that owner the Darwin Award of the Millenium!!
edited to add: I wish I could have used both the Exclamation and angry post icons on this one.....never have I seen such raging stupidity!!!
Last edited by mxslick; 07/04/0703:14 PM. Reason: Add comment and fix a typo
Over the years, I have heard a lot of 'lame excuses'! Also, I've seen a lot of fused distro panels, and a lot of 'fans' being used to help cool equipment. Fortunately, the owners listened to reason, and replaced the disasters waiting to happen. I am not advocating what is in this post, nor the excuses that are presented (lame). As an AHJ, I would have to cite this as unsafe conditions, and request immediate replacement, or repairs, if possible. John
Don't know if it's THAT bad (the fan thing, not the other violations). A guy over at a German board told this story: panel of a bowling alley, about 10 years old. When it gets hotter in summer the breakers start tripping randomly . Electrician measured, 40 amp breaker with about 28 amps load... replaced breakers several times with different brands... no result. Only a fan helps.
Tex: IF cooling airflow was required, then mfg's would install ventilation fans on the panels.
Heat disapation from branch circuit breakers is dependent of heat from adjacent cb's. Multiple cb's that operate 'warm/hot' and are next to each other cannot disapate heat. Add to this that heat 'rises'. I don't know the engineering terms, but I see the above in real life.
One situation was 1/2 size GE breakers installed in a comm application, lighting circuits loaded to 12 amps, (#10 awg) and the branch breakers were HOT. Replaced cb's, same situation....removed circuits to a sub-panel, installed full size cb's, problem gone.
Well then, What do we have here?. I hope that this "panel" is way out of the way of any kids looking to touch the pretty looking tubes and shiny metal bits. Is this panel of a propreitry type or has this been made from scratch?, I've never seen a thing like this before with so much bare live metal. High Rupturing Capacity fuses of the type used above, are designed to run cool under normal loading, even to the extent that they have multiple silver elements inside them to distribute the current evenly through the fuse. If these fuses are running warm or even hot, I would be VERY concerned as to the load being drawn through them. One other thing, frequent fuse failures can mean only one thing, bad wiring in the installation.
Let's face it, these days if you're not young, you're old - Red Green