Manhole cover blow up

[Sahib]

Manhole cover plate which is heavy blows up sometimes, rising up into the air many feet due to electrical causes inside the manhole. One study found that faults developing in old cables in the manhole is a cause. What may be other electrical causes? Thanks.

 

[dfmischler]

By any chance is this in an environment with an explosive atmosphere (e.g. a mixture of air and methane)?

 

[mbrooke]

Transformer gassing and that leaking out?

 

[kwired]

You would think if it were faults in cables, that someone would notice something is not working afterwards, they likely do not self heal.

If there are gases being ignited there has to be an ignition source - heating connections, arcing somewhere.

 

[texie]

I remember a few years back PEPCO in the Washington, DC area had quite a spat of this. The way I understand it is this comes from failing splices that arc and create explosive gases and when the conditions are just right they can explode with tremendous force.

 

[Sahib]

Thanks guys for your valuable inputs.

The study I referred to in the OP was based on big data analysis aimed to predict which manhole cover was going to blow up. The prediction was also based on the presence of old cables in the manholes. The study did not point out presence of any explosive gas such as methane in the manhole as a prerequisite for the manhole cover blow up.