Type B or C RCBO

[La Poste]

Greetings.

Friend of mine has a fridge freezer and a standing freezer that need RCBO protection.

Both these appliances run off the same socket which is a separate radial so easy to protect as it will only be these two items on this one particular circuit.

I am not sure of the starting current of these appliances and so was wondering whether to fit a type B or type C 16 Amp RCBO.

What do you think?

Thanks a lot.

 

[telectrix]

firstly, measure the Zs of the circuit. if it's above the max. for the 16A type C, ( 1.44 ohms ) . fit a type B.

 

[Deleted member 9648]

Never had a problem with a type B in these circumstances...as it is unlikely that both appliances will start at exactly the same moment there are not likely to be any issues.....I would fit whatever I happen to have,a Type B or C...as it is RCD protected Zs is not likely to be an issue either....1667 ohms applies..

 

[Engineer54]

Never had a problem with a type B in these circumstances...as it is unlikely that both appliances will start at exactly the same moment there are not likely to be any issues.....I would fit whatever I happen to have,a Type B or C...as it is RCD protected Zs is not likely to be an issue either....1667 ohms applies..

I think it does, or at least could!! RCD protection is classed as ''Additional'' in other words ''Don't Rely on it!! RCDs can and often DO fail!! Then your Zs becomes very important, very fast!! lol!!

 

[Octopus]

Greetings.

Friend of mine has a fridge freezer and a standing freezer that need RCBO protection.

Both these appliances run off the same socket which is a separate radial so easy to protect as it will only be these two items on this one particular circuit.

I am not sure of the starting current of these appliances and so was wondering whether to fit a type B or type C 16 Amp RCBO.

What do you think?

Thanks a lot.

Why do you think you need RCD protection?

 

[GLENNSPARK]

surface run it......mark the outlet for fridge/freezer only.....get round the earth leakage issues that these appliances are known to suffer from..........

 

[Amp David]

Never had any issues using Type B RCBOs for radials supplying fridgefreezers/fridges.

How large are starting currents on fridge freezers usually?

 

[GLENNSPARK]

just little compressors on em....cant see the load being that high.........

 

[Deleted member 9648]

I think it does, or at least could!! RCD protection is classed as ''Additional'' in other words ''Don't Rely on it!! RCDs can and often DO fail!! Then your Zs becomes very important, very fast!! lol!!

An RCD may be classed as either additional protection or to satisfy disconnection times....411.4.9.

If in the case of the OP if it was found that starting surges were a problem with a type B...and the Zs exceeded the maximum allowable for a type C OCPD would you rewire the circuit in a larger cable to bring it within the allowances for a type C..??,(or some other expensive fix?), when the regulations permit the RCD element of the device already installed to meet the requirements for disconnection times?
If you prefer the first option I'm glad I'm not one of your cutomers.

 

[nickblake]

I'd be inclined to go with glen sparks point and run in a radial but i would run it in a 4 or 6mm only reason is the cpc is larger in these so there fore the Zs readings should be lower i am a big fan of keeping the Zs as low as possible ,and for reasons eng54 has stated RCD's do fail , for certain circumstances you can install sockets without RCD protection

 

[telectrix]

not only fail, but trip when you are away for a few days and leave you with a soggy, expensive mess of what used to be frozen food. bang it on it's own radial, no RCD and bury the drop in a length of 20mm galv. conduit ( earthed, ofd course) sssimples.

 

[La Poste]

It's in a garage with a damp floor.
The lead sheathed TN-S cable runs right under the garage so for safety reasons I was thinking of an RCBO.

Personally I would prefer no RCD at all, the wiring is in surface clipped PVC conduit and the socket is already on its own radial but seeing as how everybody is health and safety mad these days I think it best to RCBO it.

The fuse board has a spare way which will have a 16 Amp non RCD protected MCB ready just in case the fridge freezer does trip out.

I'm really in two minds about this, maybe I will just give them a socket next to the fuse board for when they go away, they can plug their freezers into this socket whilst on holiday.

ZS is below 1 Ohm.

 

[spark 68]

Personally I would prefer no RCD at all, the wiring is in surface clipped PVC conduit and the socket is already on its own radial but seeing as how everybody is health and safety mad these days I think it best to RCBO it

Although just labelling said sockets is allowed within the regs, if you are that bothered (sockets may be used outdoors blah blah), you could put special plugs on the appliances and change the socket outlet to match, eg. you can get plugs (and sockets) where one pin is turned through 90 degrees, so nothing else will be able to be plugged in.

And put that outlet on a non RCD side of the board.

 

[SPARTYKUS]

Or cut plug off and wire it into a fused spur <WAITS for warranty expires if-you-do-that post....>

 

[Marvo]

Or cut plug off and wire it into a fused spur <WAITS for warranty expires if-you-do-that post....>

I heard a rumour that cutting moulded plugs off invalidates your car insurance and stunts the growth of any veggies your growing in your garden. :biggrin:

 

[telectrix]

I heard a rumour that cutting moulded plugs off invalidates your car insurance and stunts the growth of any veggies your growing in your garden. :biggrin:

what's car insurance? and we don't have plumbers or kitchen fitters growing in our garden.

 

[Octopus]

So its a new circuit, and thus its notifiable.

 

[La Poste]

No it's a spur off a radial.
An RCD'd spur off a radial.

 

[GLENNSPARK]

An RCD may be classed as either additional protection or to satisfy disconnection times....411.4.9.

If in the case of the OP if it was found that starting surges were a problem with a type B...and the Zs exceeded the maximum allowable for a type C OCPD would you rewire the circuit in a larger cable to bring it within the allowances for a type C..??,(or some other expensive fix?), when the regulations permit the RCD element of the device already installed to meet the requirements for disconnection times?
If you prefer the first option I'm glad I'm not one of your cutomers.

might only need an additional cpc ....parralleled up with the existing one in the cable..........

 

[GLENNSPARK]

I'd be inclined to go with glen sparks point and run in a radial but i would run it in a 4 or 6mm only reason is the cpc is larger in these so there fore the Zs readings should be lower i am a big fan of keeping the Zs as low as possible ,and for reasons eng54 has stated RCD's do fail , for certain circumstances you can install sockets without RCD protection

4mm??...bad cable to use nick mate as dont forget....still only a 1.5mm cpc..........