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MG TD TF 1500 - Fire!

Hello group, My friends TC is a total loss, electrical fire.
I will help him install an under dash battery cut off switch in his "new" TC.
Len Fanelli

Len, that is horrible! Can you publish the solution that could have avoided this on both this forum and in TSO?
Sounds like nobody was hurt? It is so important to install a cut off switch, and always disconnect it before the car is left. These things have caught fire and burned whole car collections and buildings.
D. Sander

To All,
Cut off switches are very important,, It is amazing just how fast a little electrical fire can become a very large problem. A lot of people are under the false pretense that one of those little green switches on the battery terminal are a solution,,,
Consider this,,
Driving down the road at 50 or so and you smell/see smoke,,, How long is it going to take you to bring the car to a relatively safe stop, unbuckle the seat belt, get out of the drivers seat, got around to side of the car that is the hot terminal, open the bonnet,, and turn the knob,,, assuming that it is not the carbies burning and you can not reach past the flames to get to the switch,???? Maybe even go for a ride, and tell your passenger to unexpectedly give a fire alarm at some point during the ride,,, try it and find out how long it takes!!

As Len indicated, The safest thing to do is to mount a REAL battery cut off switch where the driver can reach it quickly and kill the power! As soon as there is any indication of a fire!!!

Same with a fire extinguisher,,, make sure it is mounted where it can be accessed quickly !!!!

Hope this helps,

What would a suitable driver-accessible battery cutoff switch consist of?
Corey Pedersen 1951 TD #7169

I have a regular battery cut off switch mounted to the "hoop" under the dash,, same type that would be used for racing,,,


power goes from the battery, to the switch then back to the circuit,,, using battery cables,,,

I put mine in the glove box. Easy to reach and I have developed the habit of turning it off every time I turn off the cars ignition.
And don't make fun of my glove box. It was installed by the PO and I have since fixed it up a bit.
I have a relatively short run from the battery hot side through the fire wall and then to the switch. Then a cable back through the fire wall to the starter switch.
If I remember right, this cut-off switch has a built in standard relay and some useful terminals on the back side.

Mort Resnicoff (50 TD-Mobius)

I use the Cole Hersee mechanical switches on some equipment but I don't want to run heavy cables into the the TF.

I plan to use a solenoid in the engine compartment as such:

J E Carroll

J E Carroll, this makes sense. Can you please post pictures, links, etc. to these parts and their installation when you have completed the project in your car? This whole thread has me worried!
efh Haskell


It's going to be a while before I get to it but It's likely I won't put the starter load through the solenoid as it's just an intermittent load. I will run everything else through it.

I'll have to do some thinking if I want to use a latching relay. The main reason to do so is that it requires no power once thrown, just like a manual switch.

The Cole Hersee print is a good starting point. Their website has lots of good information. I have used many of the products over the years with good results.

J E Carroll


Search the Cole Hersee website and open the relay catalog to page 73 for a good description of the latching type. I'm on the road with only my iPad so I don't know how to capture a picture and attach it.

Once installed in a convenient place and wired as depicted, it only will need a simple momentary on push button to turn it on and off. A switch with an LED pilot light could be wired to show if it's on. A side benefit is it would be an anti-theft device as the engine will crank but not start; easily defeated with a jumper to the coil, of course.

J E Carroll

Battery cut-off, fuel pump cut switch, Fire extinguisher...all good ideas. I have all 3.
However, IMHO:
A dead short in an un-fused circuit is the only one that will burn it to the ground! The best way to avoid that is either add fuses, relays, and/or fuseable links to all circuits that are unfused. Not hard to do and can be "hidden" so not to offend.

The unfused circuits on these cars are a "welder in waiting" ...value determined only by the amperage of your battery and the gauge of your wire!
David Sheward

At the risk of offending the originality police...

I have restored several old cars, currently working on my '52TD. I have, in every case, added all new wiring and fuses. After examining those old harnesses with their brittle insulation and inadequate fuses, I have concluded that for my purposes, "A new harness is a happy harness."

I totally understand the desire for originality, and for a museum exhibit, or a concours restoration, I'm all for it. Even though my TD was a 30 year old barn find, it suffered quite a bit at the hands of its PO, so in reality the best I can do is to return it to the best approximation of what it once was. Because I intend to drive it (and stay safe) the brakes are all new from master cylinder to brake shoes; and the electrical are all new from battery to light bulb and spark plugs - and I do include a cut out switch as part of the total package.

While I usually make my own wiring harness, I have seen advertised some pretty authentic looking replacements for our cars utilizing the most modern and correctly sized wires and fuse blocks.

Most of all, I continue to be awed by the work you all are doing. Thank you for the opportunity to learn from your restorations.
RwB Brown

There's an article I've seen and printed out of someone who's developed a modern blade fuse block adaptation that avoids cutting the factory harness. Anyone know what im talking about and have the link to the online version?

Alex Waugh

If it is located in the engine compartment,,, you still have the time lapes between the "Oh Sh%$#T, we're doing 55mph and I smell smoke" and enventually getting to the push button selinoid in the engine compartment ????


I'm now in the learning curve on "master disconnect switches" thanks to this thread. It seems there are "single pole" and "double pole" versions (as well as the solenoid version mentioned above that uses thinner wire). Can anyone tell me the difference?
(Or better yet give me the colehersee part number! #75920 looks sort of like a picture above?). Here is what I'm looking at:
efh Haskell

Seems like you wouldn't need the Lock or Tag features,,, just a basic plain 2484 would work,,i didn't check price differences between them,,,


I'm still running Positive ground(earth). I have added a cig lighter with Positive center terminal to run accessories. I recently had a near meltdown when my GPS With mini-USB cable shorted to ground. Turns out the outside of the mini-USB is ground(-) which is a direct short to the (+) chassis. My utility light had the same problem. One day I'm going to switch to neg ground! (and add more fuses)
cj schmit

Question: If the car is running (i.e., the generator is putting out juice) does just removing the battery from the loop really do any good? Seems that back in the early 80's just on a lark I started the better half's Toyota and then disconnected the Pos. battery cable and the car continued to run just fine implying to me that there was still a lot of electricity being put into the circuit.

Conclusion for you to comment on: If you are going to put in a disconnect switch shouldn't you make certain that it both removes the battery from the ciorcuit AND that it removes the generator from the circuit.

Just wondering.

J K Chapin

As I said above, my switch has the main disconnect for the battery but also has a standrd relay in the back end. You could run the generator leads to the relay and when you cut of the switch it would kill the battery and anything connected to the proper terminals in the rear.
Mort Resnicoff (50 TD-Mobius)


The push button would be located in the cockpit otherwise you might as well have a mechanical switch.

Look at the wiring diagram; alternating pushes of the button either latches the relay open or closed. "I smell smoke" requires declutching to coast and a push of the button to cut off all power.

J E Carroll

This thread was discussed between 05/05/2013 and 06/05/2013

MG TD TF 1500 index

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