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holmslaw
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Electric Shower CCT
- Thread starter tony3210
- Start date
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Spark123 said:
equitum said:
But you are now assuming that ALL MI's state the specific requirement for a DP pull switch located in the bathroom !!
FACT: BS7671 does not state or imply that a shower must have a DP isolator installed in the same room, or within easy reach of the shower.
OPINION: DP pull cord switches are typically installed for convenience of isolation because otherwise the only means of isolation is the main switch in the CU, which would entail isolating the whole installation. Where this is not the case and a separate CU is installed for the shower then the main switch of such a CU is an adequate means of isolation for the shower. This has the advantage of less points of failure, less connections in a high current circuit and fewer electrical accessories in a special location.
Nope, simply saying that the MI must be followed or it automatically does not comply with BS7671.
The MI I referred to before doesn't say that the switch has to be reach of the shower, infact the opposite is said. I have seen a few where the DP isolator switch has been installed outside the bathroom door.
The MI I referred to before doesn't say that the switch has to be reach of the shower, infact the opposite is said. I have seen a few where the DP isolator switch has been installed outside the bathroom door.
Local switching.....
If i want to change a lamp (current using equipment) then isolation by the functional switch is adequate...
If i want to repair the hoover etc then either unpluging it and removing from source is adequate...
In both above instances switching off at MCB for maintenance is overkill.
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If you wish to change a ceiling rose, then what ?
If you wish to change a socket outlet, then what ?
How can you make first make an argument that a device in the consumer unit cannot be used as a means of isolation, and then not give a valid response as to how you would work on a different circuit without DP switch isolators ? (other thank think of two instances where you use a functional switch, which is not advisable) The answer is you would either have to lock off the device, or ensure it is under supervion, for example lock the doors, have an assistant ensure the device is not turned on, use warning notices etc.
FACT: BS 7671 does state that effective means, suitably placed for ready operation, shall be provided so that all voltage may be cut off from... all equipment, as may be necessary to prevent or remove danger.
FACT: An appliance drawing several 10's of amps has the potential to go nastily wrong very quickly, thus creating a situation where it may be necessary to remove danger.
OPINION: The MCB in the CU, or the main switch for the installation, is not an effective means, suitably placed, for ready operation to cut off the voltage to a shower.
OPINION: I fail to understand why this debate arises time and time again, given that I have never seen equivalent suggestions that cookers do not need a CCU within 2m of them.
H
holmslaw
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I am a layman but,
I read somewhere today, a quick 'shortening and clarification' of the regulations to be (most sites that I have read today concur with the following):
If a pull cord dual pole isolator can be installed in the same room, but out of reach of the person using the shower, this is the best solution. The pull cord rose should have at least a physical indication of power or no power. (plus possibly a neon indicator)
Otherwise, a dual pole isolating switch should be located outside of the room, but within ease of use. This switch should have an indicator (in this case not necassarily physical) of whether the circuit is live or non-live.
I would take the ease-of-use to mean that a consumer unit style box (where most that I have seen that are not in cupboards contain a plastic cover to stop accididental tripping/resetting) not to be suitable.
I read somewhere today, a quick 'shortening and clarification' of the regulations to be (most sites that I have read today concur with the following):
If a pull cord dual pole isolator can be installed in the same room, but out of reach of the person using the shower, this is the best solution. The pull cord rose should have at least a physical indication of power or no power. (plus possibly a neon indicator)
Otherwise, a dual pole isolating switch should be located outside of the room, but within ease of use. This switch should have an indicator (in this case not necassarily physical) of whether the circuit is live or non-live.
I would take the ease-of-use to mean that a consumer unit style box (where most that I have seen that are not in cupboards contain a plastic cover to stop accididental tripping/resetting) not to be suitable.
No - you can have a rotary/rocker/toggle switch on the wall if you prefer.
Why does the cord have to be out of reach?
ban-all-sheds said:
Why not. I need to isolate a shower, for maintainance. I go into the room containing the CU and isolate it by turning off the switch.
ban-all-sheds said:
OPINION:
I have seen several suggestions that the cooker switch does not need to be within 2M of the cooker. Again, where are you getting a distance of " 2meters " from, and why should this be the case ??
What if you need to isolate it because it is making a fizzing sound, and there's a smell of ozone and melted plastic coming from it, and faint wisps of smoke?
2m is generally regarded as the maximum distance away that the switch should be and still be suitably placed for ready operation.
But be that as it may - have you ever seen a suggestion that you don't need a CCU at all, and that the MCB or man switch is all you need?
Think your getting a little bit confuddled here...
A DP switch is acceptable as a means of isolation to be able to carry out maintenance work on an item of current using equipment hence a DP switch installed on a shower circuit is acceptable as a means of isolation.
Same applies to a 20A DP switch above the worktop in a kitchen that can be used to isolate,say,a built under washing machine or the like for maintenance.
I never said an MCB wasn`t acceptable for isolation
i dont think i did anyway.....No, I'm not getting confused at all. Your original point was that an MCB is only suitable as a means of isolation if it can be locked off or is under your control, implying that this is not a suitable means of isolation for a shower. My point was that this is deemed to be suitable means of isolation for say a socket outlet replacement or a ceiling rose replacement, which you countered with two poor examples of unplugging a hoover or replacing a lamp.
BAS - I see no difference in a shower or cooker in terms of isolation. A cooker may be argued to give rise to a hazard under normal operation, and as such would then require an emergency switch. This is a different requirement to a switch for isolation.And because a distance of "2M is generally accepted" that doesn't make it a regulation. I seem to recall you going to great lengths on a recent post to argue what people think or generally do does not alter what is a regulation or what isn't. I suppose it comes down to the semantics of "ready operation" to remove or prevent danger. If my cooker or shower were popping or on fire then I would deem a 3 second walk to an adjacent room or cupboard to isolate the appliance ready enough. That is of course, assuming the EEBADS system and supplementary protection where fitted has not automatically disconnected the appliance, which it should have been designed to do. And I would probably feel safer being outside a shower room, especially if wet, or outside a kitchen, if on fire, to do so !
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