Trip Switches & Power

[DrWho]

A trip switch box has recently been installed into a new build, where I am just now when a bulb blows say in the dining room all that happens is the bulb itself has blown and obviously unusable and the trip switch for those lights is isolated and off, is this normal or should the power in the whole house be automatically turned off when this occurs? or should it be just the one trip switch pertaining to those particular lights?

 

[DrWho]

To avoid any confusion, when I mentioned where I am just now is different from the new build, I was just comparing the two.

 

[EFLImpudence]

A trip switch box has recently been installed into a new build, where I am just now when a bulb blows say in the dining room all that happens is the bulb itself has blown and obviously unusable and the trip switch for those lights is isolated and off, is this normal or should the power in the whole house be automatically turned off when this occurs?

Yes, that is normal. Hence why there are separate switches.

Trip switch - miniature circuit breaker (MCB) detects overload and fault current -
or residual current device (RCD) detects earth leakage, which covers several MCBs -
or residual current device with overload protection (RCBO) which combines both functions.
Trip switch box - consumer unit.

or should it be just the one trip switch pertaining to those particular lights?

Yes, just the one trip switch.
It's not a question of "should".
Depending on the bulb and the fault, it probably will trip the switch but it would not matter if it didn't.

 

[DrWho]

A trip switch box has recently been installed into a new build, where I am just now when a bulb blows say in the dining room all that happens is the bulb itself has blown and obviously unusable and the trip switch for those lights is isolated and off, is this normal or should the power in the whole house be automatically turned off when this occurs?

Yes, that is normal. Hence why there are separate switches.

Trip switch - miniature circuit breaker (MCB) detects overload and fault current -
or residual current device (RCD) detects earth leakage, which covers several MCBs -
or residual current device with overload protection (RCBO) which combines both functions.
Trip switch box - consumer unit.

or should it be just the one trip switch pertaining to those particular lights?

Yes, just the one trip switch.
It's not a question of "should".
Depending on the bulb and the fault, it probably will trip the switch but it would not matter if it didn't.

Ah ok, so I would still have power in the new build home if a light blows, I'm positive that the bloke that showed us around said that it would automatically switch off all power for safety, or is that for certain appliances like a cooker element for example?

 

[EFLImpudence]

Ah ok, so I would still have power in the new build home if a light blows,

No different from how it's always been.

I'm positive that the bloke that showed us around said that it would automatically switch off all power for safety, or is that for certain appliances like a cooker element for example?

No. Possibly a misunderstanding on his or your part.

Blokes who show people around houses are not electricians, nor plumbers, nor builders etc.

 

[DrWho]

Blokes who show people around houses are not electricians, nor plumbers, nor builders etc.

Sorry but I meant to say the bloke who was explaining things was the developer site manager.

 

[DrWho]

Thanks EFLImpudence for confirming what I thought all along, I'll be speaking to them again soon.

I remember where I am just now when a cooker element blew it switched off all power to the house, would I be right in thinking this occurred because the RCD kicked in for safety especially as I could have been touching something inside the cooker at the time that it blew and a live current could have caused an electric shock?

 

[EFLImpudence]

I remember where I am just now when a cooker element blew it switched off all power to the house,

It could have been one RCD covering all the circuits.

would I be right in thinking this occurred because the RCD kicked in for safety especially as I could have been touching something inside the cooker at the time that it blew and a live current could have caused an electric shock?

It could have been that, or

it could have been just a failing element where no actual danger would have been present but the RCD can't tell the difference.

Swings and roundabouts.

 

[DrWho]

I remember where I am just now when a cooker element blew it switched off all power to the house,

It could have been one RCD covering all the circuits.

would I be right in thinking this occurred because the RCD kicked in for safety especially as I could have been touching something inside the cooker at the time that it blew and a live current could have caused an electric shock?

It could have been that, or

it could have been just a failing element where no actual danger would have been present but the RCD can't tell the difference.

Swings and roundabouts.

Thanks, I'm beginning to understand all this eventually lol.

 

[SimonH2]

the bloke who was explaining things was the developer site manager.

Doesn't really change the discussion - probably no idea about electrics.
the things is, the reason (well one of the reasons) we have multiple circuits with their own protection is so that a fault (eg the temporary short circuit that often happens when a bulb blows) does NOT cut off all power.

It's why installations tend to have two RCDs (not to be confused with MCBs) these days - and ideally the light and power citcuits will be split across them so that an RCD tripping will leave some of the lights and some of the power still on.
An RCD on every circuit (using an RCBO - combined MCB and RCD) is better but generally costs quite a bit more and you'll rarely (if ever ?) see a developer putting them in a new build as to them it's wasting money that would be better kept in their profits.

MCB - the device that detects excessive current (short or overload). RCD - device that detects leakage to earth, such as (it's primary function) because someone's touched something live.