RCD NEEDED OR NOT?

[maax555]

Hi, I have purchased a Blagdon Powersafe Armoured Garden power supply kit. It states that its complies fully with IEE wiring regulations and can be fitted by a competent person. I am basically running this to a 5 way IP66 rated switch box for garden lights, pond pump, waterfall and decking lights. The instructions say that to comply with regulations the cable must be plugged into an RCD socket. My question is this, as my consumer fusebox is a dual RCD type can i run twin and earth (2.5mm) to a standard spur and then plug the cable in here direct?

Actually a second question while I am here is once this 5 way switch box is fitted, can i run an armoured cable from the switch box (gland) to the first 240v/42w Lamp and then daisy with standard twin and earth clipped to underside of decking?

any thoughts would be welcome.

 

[JohnW2]

The instructions say that to comply with regulations the cable must be plugged into an RCD socket. My question is this, as my consumer fusebox is a dual RCD type can i run twin and earth (2.5mm) to a standard spur and then plug the cable in here direct?

If the circuit to which you are connecting it is already RCD protected, then you do not require any additional RCD protection. If the circuit in question is a ring circuit, then you can only run a spur such as you describe if you are certain that the socket from which you are 'spurring' was part of the ring, and not itself already a spur.

Actually a second question while I am here is once this 5 way switch box is fitted, can i run an armoured cable from the switch box (gland) to the first 240v/42w Lamp and then daisy with standard twin and earth clipped to underside of decking?

You will probably get varying answers to that - some people feel that ordinary T+E is not suitable for any outside use, although what you describe does not sound particularly unreasonable (unless there are rodents beneath your decking which are likely to nibble at the cable!) - although definitely not ideal. How would you propose to terminate the SWA at the first lamp (light fittings are often not suitable for accepting an SWA gland)?

Kind Regards, John

 

[maax555]

The instructions say that to comply with regulations the cable must be plugged into an RCD socket. My question is this, as my consumer fusebox is a dual RCD type can i run twin and earth (2.5mm) to a standard spur and then plug the cable in here direct?

If the circuit to which you are connecting it is already RCD protected, then you do not require any additional RCD protection. If the circuit in question is a ring circuit, then you can only run a spur such as you describe if you are certain that the socket from which you are 'spurring' was part of the ring, and not itself already a spur.

The ring circuit down stairs is RCD protected but I was going to run a new sit straight to an unused fuse in the fuseboxes which is already RCD. I was going to run the T&E around the rear of the kitchen units as it would be hidden. When I say run I mean straight from fusebox, clip it once near by for strain relief then run along the back of the unit with no fixing as there is no access with removing cupboards and then a wall mounted skt under the bench at ear of washing machine.

Actually a second question while I am here is once this 5 way switch box is fitted, can i run an armoured cable from the switch box (gland) to the first 240v/42w Lamp and then daisy with standard twin and earth clipped to underside of decking?

You will probably get varying answers to that - some people feel that ordinary T+E is not suitable for any outside use, although what you describe does not sound particularly unreasonable (unless there are rodents beneath your decking which are likely to nibble at the cable!) - although definitely not ideal. How would you propose to terminate the SWA at the first lamp (light fittings are often not suitable for accepting an SWA gland)?

The connections for each lamp are simply terminal blocks which are then housed in a protective plastic box and are inside each lamp and are about 100mm up each stainless steel tube. The protective boxes are splash proof at best but should be ok. We have never had a problem with rodents but then again we have never had plastic wires for them to feast on

Kind Regards, John

 

[JohnW2]

The ring circuit down stairs is RCD protected but I was going to run a new sit straight to an unused fuse in the fuseboxes which is already RCD. ...

If you take that approach you would be creating a 'new circuit', which would be 'notifiable work'. That means that you'd either have to get a registered 'self-certifying' electrician to do the work or else pay your local authority (possibly 'a few hundred pounds') if you notified yourself.

Kind Regards, John

 

[maax555]

The ring circuit down stairs is RCD protected but I was going to run a new sit straight to an unused fuse in the fuseboxes which is already RCD. ...

If you take that approach you would be creating a 'new circuit', which would be 'notifiable work'. That means that you'd either have to get a registered 'self-certifying' electrician to do the work or else pay your local authority (possibly 'a few hundred pounds') if you notified yourself.

Kind Regards, John[/requote]

Ah ok then I will stick to an existing circuit. I have a single skt that runs from a fused switch, which is a spur off a ring skt. I could change this to a double skt and run washer and garden electrics off the double skt as I believe it has 2.5mm cable. Shoul i still fit RCD to plug to garden or would RCD at fusebox be enough. To be honest for sake of £10 I would rather fit one unless it would be a problem.

Thanks

 

[JohnW2]

Ah ok then I will stick to an existing circuit. I have a single skt that runs from a fused switch, which is a spur off a ring skt. I could change this to a double skt and run washer and garden electrics off the double skt as I believe it has 2.5mm cable.

fair enough. If that existing fused spur has been wired correctly (i.e. directly from the ring, not from a spur), then that would be OK.

Shoul i still fit RCD to plug to garden or would RCD at fusebox be enough. To be honest for sake of £10 I would rather fit one unless it would be a problem.

As I said before, if the circuit is already RCD-protected, you don't need an additional RCD - so there's no reason do do that unless you just want the reassurance of 'belt and braces'. However, if you do take that approach, you need to understand that there is no telling which (or both) of the RCDs would trip in the case of a fault.

Kind Regards, |John

 

[ericmark]

The Blagdon Powersafe Armoured Garden power supply kit was a way to get around the Welsh and old English Part P law where if the system was pre-built then it was permitted without needing to inform the LABC.

They are not as water proof as they claim so using a little petroleum jelly on plugs will normally help ensure they are water proof.

Since in England you no longer need the get around the law system but the 13A RCD plug often supplied also has a 13A fuse in it so if you don't use the plug supplied you will still need a fuse either a FCU or simple 13A plug.

I was not impressed with the Blagdon system to me having to remove and re-fit the plug while putting cable through the wall resulted in it not complying to old English rules and the volt drop could be excessive. However it is easy to fit and I can see why it's popular.

Personally for garden electrics I like the 10mA RCD but they are hard to find suppliers now. Remember a RCD does not stop you getting a shock it only limits the time you get the shock for.

 

[AndyPRK]

humm. example kit

http://www.ebay.co.uk/itm/Blagdon-P...ondsWaterFeatures_UK&var=&hash=item1c429588ee

 

[JohnW2]

Personally for garden electrics I like the 10mA RCD but they are hard to find suppliers now. Remember a RCD does not stop you getting a shock it only limits the time you get the shock for.

As you say, an RCD does not stop you getting a shock, and nor does it limit the current of the shock - it merely limits the duration of the shock. I therefore wonder why you prefer a 10mA for garden electrics?

Kind Regards, John

 

[ban-all-sheds]

Because the duration-limiting kicks in at a lower current?

20mA when you're up a wet metal stepladder cutting a hedge whilst over-reaching might be more exciting than you'd like.

 

[JohnW2]

Because the duration-limiting kicks in at a lower current?

Well, that's obviously essentially the only difference, so is only going to make any difference with shock currents between 10mA and 30mA - which are (when they flow for a few tens of ms) unlikely (but not guaranteed not to!) to do any serious direct electrical harm ...

20mA when you're up a wet metal stepladder cutting a hedge whilst over-reaching might be more exciting than you'd like.

True, but not really much more of a risk than if one is up a stepladder in one living room, or up a ladder in one's stairwell, with a power tool in one's hand. There is obviously some benefit in always having an IΔn as low as possible, but I'm not convinced that it's really materially different outdoors. If it weren't for leaky appliances/equipment, I presume we would use 10mA, or lower, for everything.

... and, in passing, if one is touching a 'wet metal stepladder' which is standing on soil, I would think it's very unlikely that the shock current would be anything like as low as 20mA!

Kind Regards, John