Consumer unit wiring

[Tonydom]

Hi folks this might be a really stupid question but I would rather sound stupid than end up dead. I'm about to wire up my 240 electrics but my consumer box only has one busbar surely the neutral and earth don't share a busbar, all other CU I have done in the past have had two separate busbar one for earth and one for neutral

 

[pappajohn]

Use that busbar for the neutrals and connect all earth's in a 60amp choc block making sure both clamp screws are used.... A 30amp block may be big enough but that large earth will dictate .
Don't forget to link the busbar to neutral of the main switch.

 

[tonyidle]

The plain copper connector bar at the top is earth. The Neutrals are presumably commoned behind the breakers. However that box isn't ideal. Best practice is for the MCBs to switch both Live and Neutral in the same way as the RCB.

 

[pappajohn]

The plain copper connector bar at the top is earth. The Neutrals are presumably commoned behind the breakers. However that box isn't ideal. Best practice is for the MCBs to switch both Live and Neutral in the same way as the RCB.

It can be either earth or Neutral.... When there are two bus neither is enclosed.
Better neutral in a busbar than earth.
I can't imagine another bus behind the breakers... That would make installation difficult.

 

[tonyidle]

It can be either earth or Neutral.
Better neutral in a busbar than earth.
I can't imagine another bus behind the breakers... That would make installation difficult.

Agreed - but it has to be somewhere. Given the limited number of connections though I'd be tempted to use the Neutral terminal of the RCB as common Neutral which is probably what's intended. It isn't a particularly good device.

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[pappajohn]

Agreed - but it has to be somewhere. Given the limited number of connections though I'd be tempted to use the Neutral terminal of the RCB as common Neutral which is probably what's intended. It isn't a particularly good device.

Agreed, but using a common terminal could cause problems when fault finding.
If the bus is used it should correspond to each breaker... Left breaker and first hole of bus on left.
Then a circuit can be tested without removing all neutrals.
But basically that box isn't big enough.

 

[tonyidle]

But basically that box isn't big enough.

That's the real problem.

 

[Lenny HB]

Also the total of your MCB's is 61 amps should not be more than 16 amps.
Our van is German and only has one double 10 amp MCB, you could fit one or a 16 amp double pole MCB would solve your neutral problem.

A lot of vans have a 6 amp & 10 amp MCB the 6 amp feeding the fridge and charger, 10 amp for the rest.

 

[pappajohn]

Also the total of your MCB's is 61 amps should not be more than 16 amps

Can't understand what would need a 40amp breaker on a motorhome..... The hookup post will only be 16amp.
Most likely how the unit was supplied.

 

[stevewagner]

If I were you I would get rid of the 40amp breaker and fit a blanking plate. There will be a neutral connecting block somewhere behind the breakers. You should not use the earth block for neutral as it is exposed and insulated and could become live under a fault condition.

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[pappajohn]

You should not use the earth block for neutral as it is exposed and insulated

Have a look in any unit.... Both earth and neutral bars are unprotected

 

[stevewagner]

Have a look in any unit.... Both earth and neutral bars are unprotected

True but the neutral is usually covered by the switchgear

 

[Odd-no-more]

True but the neutral is usually covered by the switchgear

True but if you're poking about in a consumer unit with the power on you probably deserve a shock

 

[dunnah01]

True but the neutral is usually covered by the switchgear

Not any any CUs I've seen? Earth and Neutral have always been unshielded at top of unit

 

[stevewagner]

True but if you're poking about in a consumer unit with the power on you probably deserve a shock

True but turn the power off and it’s still live to the isolator unless you can pull the main fuse which requires braking the seal. Technically only a qualified sparks should do that although I’ve attended many properties where the seal is broken.

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[Tonydom]

Thank once again guys I think I will just buy another CU any recomendations

 

[pappajohn]

Not any any CUs I've seen? Earth and Neutral have always been unshielded at top of unit

Thank you..... Either top or at each side and a plain copper bar fixed to the back, top or sides.
There isn't usually room behind the breakers for heavy wires never mind a brass busbar.

 

[xsparks]

Surely the supply goes in the bottom and the live and neutral should be prewired, therefore a link should already go from the N terminal to the existing bus bar.

 

[Lenny HB]

Have a look in any unit.... Both earth and neutral bars are unprotected

Neutral is bonded to earth anyway, if the bonding is not that local the neutral will only be a few volts above earth .

 

[pappajohn]

Neutral is bonded to earth anyway, if the bonding is not that local the neutral will only be a few volts above earth .

Yep, usually at the local substation.

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[dunnah01]

Thank you..... Either top or at each side and a plain copper bar fixed to the back, top or sides.
There isn't usually room behind the breakers for heavy wires never mind a brass busbar.

And then I go and Google to check sanity and find the exception to prove the rule

 

[Odd-no-more]

Neutral is bonded to earth anyway, if the bonding is not that local the neutral will only be a few volts above earth .

Only in a PME earth system a TNCS or a TT earth are independent of neutral

 

[Rob Turner]

Yep, usually at the local substation.

Or on an overhead system then every 7 poles max and every terminal pole.

 

[Rob Turner]

True but turn the power off and it’s still live to the isolator unless you can pull the main fuse which requires braking the seal. Technically only a qualified sparks should do that although I’ve attended many properties where the seal is broken.

The seal can only be broken by the DNO or the Energy Retailer.
The spark has no right in breaking a seal. All new supplies should be fitted with a DP isolator before the CU

 

[Lenny HB]

Only in a PME earth system a TNCS or a TT earth are independent of neutral

You are just trying to confuse me.

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[pappajohn]

And then I go and Google to check sanity and find the exception to prove the rule

View attachment 454014

Wouldn't expect to see an old red and black in there.

 

[Rob Turner]

Wouldn't expect to see an old red and black in there.

Proper electric

 

[dunnah01]

Wouldn't expect to see an old red and black in there.

Or a plastic box

 

[Odd-no-more]

The seal can only be broken by the DNO or the Energy Retailer.
The spark has no right in breaking a seal. All new supplies should be fitted with a DP isolator before the CU

You are right, but I've broken a few seals over the years

 

[berni109]

More than I very wanted to know about earth systems.
Tonydom link to consumer unit wiring - this guy has several YouTube vids about more modern units

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